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Microsoft Multipath I/O Best Practices
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Dell Best Practices
Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices
Kris Piepho, Microsoft Product Specialist January 2015
2 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
Revisions
Date Description
10/11/2010 Initial release
10/21/2011 Corrected Errors
11/29/2011 Additional content on Server Core
10/15/2012 Updated to include Windows Server 2012 content
5/29/2013 Updated to include Server 2008 R2/2012 iSCSI initiator setup and appendix listing recommended hotfixes and registry values
10/18/2013 Updated to include Windows Server 2012 R2 content
1/10/2014 Updated hotfix information
1/12/2015 Updated configuration recommendations
THIS WHITE PAPER IS FOR INFORMATIONAL PURPOSES ONLY, AND MAY CONTAIN TYPOGRAPHICAL ERRORS AND TECHNICAL INACCURACIES.
THE CONTENT IS PROVIDED AS IS, WITHOUT EXPRESS OR IMPLIED WARRANTIES OF ANY KIND.
© 2015 Dell Inc. All rights reserved. Reproduction of this material in any manner whatsoever without the express written permission of Dell Inc. is
strictly forbidden. For more information, contact Dell.
Dell, the DELL logo, the DELL badge, and Dell Compellent are trademarks of Dell Inc. Microsoft®, Windows®, Windows Server®, and Windows
PowerShell® are either trademarks or registered trademarks of Microsoft Corporation in the United States and/or other countries. Other trademarks
and trade names may be used in this document to refer to either the entities claiming the marks and names or their products. Dell disclaims any
proprietary interest in the marks and names of others.
3 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
Table of contents Revisions .................................................................................................................................................................................................. 2
1 Preface .............................................................................................................................................................................................. 5
1.1 Audience ................................................................................................................................................................................ 5
1.2 Purpose .................................................................................................................................................................................. 5
1.3 Disclaimer ............................................................................................................................................................................. 5
1.4 Customer support ............................................................................................................................................................... 5
2 Introduction to Microsoft Multipath I/O .................................................................................................................................. 6
2.1 Multipath I/O overview ...................................................................................................................................................... 6
2.2 Dell Compellent Storage Center connections ............................................................................................................ 6
2.2.1 Legacy ports ........................................................................................................................................................................ 6
2.2.2 Virtual ports ........................................................................................................................................................................... 7
2.2.3 Conclusion ........................................................................................................................................................................... 8
3 Configuring servers ....................................................................................................................................................................... 9
3.1.1 Fibre Channel ...................................................................................................................................................................... 9
3.1.2 iSCSI ....................................................................................................................................................................................... 9
3.2 Automatic configuration ................................................................................................................................................. 10
3.3 Manual configuration ....................................................................................................................................................... 11
3.4 Verifying connectivity ....................................................................................................................................................... 11
3.5 Choose the I/O transport ................................................................................................................................................14
4 MPIO for Windows Server 2003 ................................................................................................................................................ 15
4.1 Dell Compellent Multipath Manager ............................................................................................................................. 15
4.2 Configuration .....................................................................................................................................................................16
4.3 Choosing a failover policy ...............................................................................................................................................16
4.4 iSCSI multipath options .................................................................................................................................................... 17
4.4.1 Installing the Microsoft iSCSI DSM ................................................................................................................................ 17
4.5 Configuring the iSCSI Initiator ....................................................................................................................................... 18
4.6 Configuring Microsoft iSCSI DSM ................................................................................................................................. 20
5 Using MPIO on Windows Server 2008 and 2008 R2 .......................................................................................................... 23
5.1 Installing the Microsoft MPIO DSM .............................................................................................................................. 23
5.1.1 Server manager GUI ......................................................................................................................................................... 23
5.1.2 Server manager CLI (2008 and 2008 R2 only) .......................................................................................................... 23
4 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
5.1.3 To install MPIO on Server Core: .................................................................................................................................... 23
5.2 Associating Dell Compellent volumes with the DSM ............................................................................................... 24
5.3 Setting the default load balance policy ....................................................................................................................... 25
5.3.1 Windows Server 2008 default load balance policy .................................................................................................. 25
5.3.2 Windows Server 2008 R2 default load balance policy ............................................................................................ 25
5.4 Per-volume load balance settings ................................................................................................................................ 26
5.4.1 Using MPCLAIM in Windows Server 2008 R2, 2012 and 2012 R2 ......................................................................... 27
6 MPIO for Windows Server 2012 and 2012 R2 ....................................................................................................................... 28
6.1 Install the Microsoft MPIO feature ................................................................................................................................ 28
6.1.1 Server manager GUI ......................................................................................................................................................... 28
6.1.2 Enable MPIO with PowerShell ....................................................................................................................................... 30
6.2 Associate Dell Compellent volumes with the in-box DSM ..................................................................................... 30
6.2.1 Using the MPIO control panel ........................................................................................................................................ 31
6.2.2 Using PowerShell .............................................................................................................................................................. 33
6.3 Set the Default Load-Balancing Policy ........................................................................................................................ 34
6.4 Per-volume load balance settings ................................................................................................................................ 35
6.4.1 Using the disk management GUI: ................................................................................................................................. 35
6.4.2 Using PowerShell .............................................................................................................................................................. 36
7 Configure a Windows 2008 R2, 2012 and 2012 R2 Server for iSCSI MPIO .................................................................... 38
7.1 Configuration .................................................................................................................................................................... 39
A Windows Server MPIO configuration recommendations for Dell Compellent Storage Center ................................ 43
B Additional resources ................................................................................................................................................................... 50
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1 Preface
1.1 Audience This document was written for system administrators responsible for the setup and maintenance of
Windows® servers and associated storage. Readers should have a working knowledge of Windows and the
Dell Compellent™ Storage Center.
1.2 Purpose This document provides an overview of Multipath I/O (MPIO) and introduces best practice guidelines for
configuring MPIO on Windows Server® 2003, 2008, 2008 R2, 2012 and 2012 R2 when using the Dell
Compellent Storage Center. For installation procedures, download the MPIO Users Guide from
http://knowledgecenter.compellent.com.
1.3 Disclaimer The information contained within this document provides general recommendations. Configurations will
vary in customer environments due to individual circumstances, budget constraints, service level
agreements, applicable industry-specific regulations, and other business needs.
1.4 Customer support Dell Compellent provides live support at 1-866-EZSTORE (866.397.8673), 24 hours a day, 7 days a week,
365 days a year. For additional support, email Dell Compellent at [email protected]. Dell
Compellent responds to emails during normal business hours.
6 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
2 Introduction to Microsoft Multipath I/O
2.1 Multipath I/O overview Microsoft® MPIO is a framework that allows administrators to configure load balancing and failover
processes for Fibre Channel and iSCSI connected storage devices. Load balancing can be configured to
use up to 32 independent paths from the connected storage devices.
Dell Compellent Storage Centers provide redundancy and failover with multiple controllers and RAID
modes. However, servers still need a way to spread the I/O load and handle internal failover from one path
to the next. This is where MPIO plays an important role. Without MPIO, servers see multiple instances of
the same disk device in Disk Management.
The MPIO framework uses Device Specific Modules (DSM) to allow path configuration. Currently there are
two options available:
Microsoft provides a built-in generic Microsoft DSM (MSDSM) for Windows Server 2008 and above.
This MSDSM provides adequate functionality for Dell Compellent customers.
Dell Compellent provides a DSM for Windows Server 2003.
2.2 Dell Compellent Storage Center connections Before reviewing server-specific MPIO functions, it is important to understand that various connection
options are available with the Dell Compellent Storage Center which allows multiple paths to be presented
to the servers. The following section provides a quick overview and explains the differences between
legacy port mode and virtual port mode. This overview does not take the place of the Storage Center
Connectivity Guide available on http://kc.compellent.com
2.2.1 Legacy ports In legacy mode, the front-end I/O ports are designated as either primary or reserve ports based on a fault
domain. Primary/reserved ports allow I/O to use the primary path; the reserve port is in a standby mode
until a primary port fails over to the reserve port. In terms of MPIO, this requires twice as many I/O ports to
enable multiple paths. Even more ports are required for a dual fabric. Figure 1 illustrates dual-fabric failover
ports in legacy mode.
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Figure 1 Legacy primary/reserve configuration
Figure 1 shows four fault domains connected to a Series 40 Dell Compellent Storage Center with two
controller heads. Each fault domain has a primary and reserved port. For redundancy, a primary port
connects to one controller, and the reserved port in that fault domain connects to the other controller.
While this is a highly robust failover solution, it requires a large number of ports. For this reason, Dell
Compellent implemented virtual ports.
2.2.2 Virtual ports Dell Compellent introduced virtual port mode with Storage Center 5.0. Virtual ports allow all front-end I/O
ports to be virtualized. All front-end I/O ports can be used at the same time for load balancing as well as
failover to another port. Virtual ports are available for Fibre Channel connections only, iSCSI connections
only, or both Fibre Channel and iSCSI.
Fibre Channel
To use virtual ports for Fibre Channel, all Fibre Channel switches and HBAs must support N_Port ID
Virtualization (NPIV).
Figure 2 Virtual Port Configuration
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Figure 2 shows a virtual port configuration. All ports of one transport type (Fibre Channel or iSCSI) are in
the same fault domain. All ports are active. If one port fails, the load is distributed between remaining
ports. Failover with this configuration uses half the ports and is just as robust as the one shown in Figure 1.
iSCSI
iSCSI follows the same wiring and port setup as Fibre Channel with the exception of the control port. iSCSI
uses a control port configured for each of the fault domains. Servers connect to the control port, which
then redirects traffic to the appropriate virtual port. When configuring MPIO, this looks slightly different
than with the legacy mode configuration because only the control port in the iSCSI Initiator software
needs to be assigned. These differences are covered below in the OS-specific sections of this document.
2.2.3 Conclusion There are two methods to enable multiple paths from the Dell Compellent Storage Center: legacy port
mode and virtual port mode. Virtual ports are preferred because they reduce the number of HBAs required
and thus reduce cost and overhead. Note that virtual ports are enabled based on protocol: virtual ports
can be enabled on Fibre Channel only, iSCSI only, or both.
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3 Configuring servers Before configuring MPIO at the operating system level, first configure servers using the Dell Compellent
System Manager. The following example assumes a server has two or more Fibre Channel or iSCSI I/O
ports that are zoned or VLAN’d to see the Storage Center host bus adapters (HBAs). With Fibre Channel,
the process is the same for virtual ports as it is for legacy ports. However, with legacy ports, the server
cannot see reserve ports. iSCSI virtual ports connect only to a control port on the Storage Center.
3.1.1 Fibre Channel To create the server, properly zone the switches so that the server and controller ports are in the same
zone. The easiest way to do this is to boot the server into the card's BIOS and scan the SCSI devices on
each port. An alternate method is to preconfigure the WWNs of the HBAs in the Storage Center System
Manager.
3.1.2 iSCSI As with Fibre Channel, an iSCSI server can be created automatically or manually. For automatic
configuration, enter the IP address of the Storage Center controller HBA ports in the server iSCSI HBA or
Initiator Software. Use either the HBA BIOS or the Software Initiator configuration wizard. In virtual port
mode, enter the IP address of the control port. In legacy port mode, enter the IP address of the primary
port. This is covered in more detail in the OS specific sections. However, creating a server in the Storage
Center is the same on all operating systems.
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3.2 Automatic configuration Once a server has scanned for devices or logged into the target, Storage Center automatically recognizes
the WWN/IQN. To configure a server:
1. Log in to the Dell Compellent System Manager.
2. In the tree view, right-click on Servers.
3. From the shortcut menu, select Create Server.
4. Select the appropriate HBAs and continue the wizard. If the HBA does not appear, refer to
Section 3.3, Manual configuration.
Note: If the WWN or IQN is not listed, make sure that the Only Show Up Connections box is not
checked.
Figure 3 Create Server window
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3.3 Manual configuration To manually configure an HBA:
1. In the Create Server wizard shown in Figure 3, click Manually Define HBA.
2. In the Select Transport Type window, choose Fibre Channel or iSCSI.
3. Enter the WWN or iSCSI name, and click Continue. Repeat steps 1-3 for every WWN or iSCSI HBA
to be associated with the server.
4. Once all HBAs are added, check the appropriate HBA and continue the wizard.
Note: The new HBA appears with a white X in a red circle. Once the server is connected the warning
state is removed.
Figure 4 Manually defined HBA
3.4 Verifying connectivity To verify that the connectivity is correct:
1. In the tree view, select a server.
2. Click Connectivity. This window shows all paths available to the server based on the HBA and
controller ports.
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Figure 5 Connectivity tab
The connectivity tab displays the HBAs and controller ports that the server can see.
For Fibre Channel there are four possible paths because two HBAs see two Storage Center ports.
However, for iSCSI, there are a total of six connections where there are two separate IP addresses
going to three Storage Center ports. If MPIO is not installed and the volume is mapped using the
default mapping method, the server has visibility to a total of 10 paths to a volume.
In Storage Center, a volume is mapped to all available paths unless the advanced mapping button is used
to restrict mapping paths to FC only, iSCSI only, or specified HBA ports and controller ports. To restrict
mapping paths:
1. In the tree view, right-click a volume and select Map Volume to Server. The Map Volume to
Server window appears.
2. Select a server and click Continue. The Map Volume window appears.
3. Click Advanced.
4. Check Only map using specified server ports.
5. Select one of the following:
- Limit ports by transport type. Select a transport from the drop-down menu.
-or-
- Map using specific server ports. Check the specific server ports.
13 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
Figure 6 Advanced Mapping wizard
Assuming the default mapping wizard is used and paths are not restricted, a volume is mapped to all
available paths, creating multiple I/O paths from the server to the volume.
To view the mapped paths, select a volume in the tree view and click the Mapping tab.
Figure 7 Volume Mapping tab
Figure 7 shows that MPIO Volume 1 was mapped to the server with four FC ports and two iSCSI ports.
14 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
3.5 Choose the I/O transport Most organizations today have settled on either Fibre Channel or iSCSI for the I/O transport mechanism.
With the advent of 10GB iSCSI, the performance gap between these two transports has narrowed.
Choosing between these two depends on what the organization has in place today and where they are
heading in the future. Dell Compellent offers 8GB and 16GB Fibre Channel and 10GB iSCSI. For a
converged fabric iSCSI is the best option because it can utilize existing networking infrastructure.
The remainder of this document focuses on specific MPIO configuration options available from:
Windows Server 2003 Dell Compellent-provided DSM
Windows Server 2008 and above MSDSM
Microsoft iSCSI DSM
It is assumed that there are multiple front-end controller paths to the servers and that the servers have
multiple connections to the controller.
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4 MPIO for Windows Server 2003 Windows Server 2003 offers two methods for handling MPIO:
Storage Center ISV-provided DSM
Microsoft iSCSI DSM
These two methods cannot be used concurrently in the Windows 2003 platform. This chapter describes
each of these options and provides guidance on how to configure MPIO with both the Storage Center
DSM and the Microsoft DSM.
4.1 Dell Compellent Multipath Manager The Dell Compellent Multipath Manager is a Dell Compellent-provided DSM that handles all Fibre Channel
and iSCSI failover and load balancing. Fibre Channel requires the Dell Compellent Multipath Manager.
iSCSI can be configured with either the Microsoft iSCSI DSM or the Dell Compellent Multipath Manager.
For information on installing and configuring the Dell Compellent Multipath Manager, refer to the Storage
Center Multipath I/O (MPIO) Manager for Microsoft Servers User Guide on the Dell Compellent Knowledge
Center.
Once the Dell Compellent DSM has been installed, configure the load balance policies for the volumes
attached to the server. The default load balance policy for the Dell Compellent DSM is failover-only.
However, this can be changed to round robin or round robin subset.
Failover only: Only one path is active. I/O fails over to the next available standby path only when the
active path fails. The new active path remains active until another failover occurs. By default, the first
discovered path is the active path. You can configure the failover only policy to behave as failback by
setting the active path and enabling the preferred path option. For failback, the system fails back to
the original active path when it becomes available after a failover.
Round robin: All paths are active and I/O is distributed across all paths.
Round robin subset. Allows multiple active and standby paths; I/O is distributed across all active
paths. Standby paths are used only when all active paths fail. The round robin subset policy can be
configured to behave as failback by explicitly setting one or more active paths. For failback, the
system fails back to the original active path when it becomes available after a failover.
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4.2 Configuration To configure the default load balance policy or to change the active configuration of the DSM, open the
Dell Compellent Multipath Manager Configuration wizard from the Program Files menu. Below is a brief
overview of how to change the policies.
To change the default load balance policy for all future volumes attached to the system:
1. Click Set Default Policy at the top of the screen.
2. In the Policy field, select a policy for the environment.
To change the policy for a given device:
1. Click on the device.
2. From the drop down menu, select the desired load balance policy.
Note: If moving to a round robin policy, notice that the device paths do not change from standby to
active until the settings are applied and the wizard is restarted or refreshed.
4.3 Choosing a failover policy Determining the best failover policy is accomplished by deciding which is more important for the
application: failover, performance, or a combination of both. Cost also plays a significant role in the
decision since having multiple paths adds to the overall cost of a solution. However, in today's world of
zero downtime, failover is required in most organizations.
As mentioned previously in failover only mode, the server uses only one path at a time. While this ensures
redundancy, it may not provide adequate bandwidth for certain workloads. Also, any I/O ports in standby
mode are sitting idle until a failover occurs, resulting in underutilized resources in a data center.
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Round robin, on the other hand, provides a means for I/O to traverse all available paths while still providing
a level of redundancy. If one path fails, the system uses the remaining paths to complete the request.
4.4 iSCSI multipath options As mentioned previously, the Dell Compellent Multipath Manager handles both FC and iSCSI connections.
In the Dell Compellent Configuration window, the transport for each connection can be viewed and
configured for each volume.
Figure 8 Dell Compellent DSM with both FC and iSCSI
However, if the built-in Microsoft iSCSI DSM is installed, the Dell Compellent Multipath Manager software
must be uninstalled. Typically this is done for a server with volumes connected only via the iSCSI transport.
Otherwise there is no way to control the Fibre Channel MPIO functionality. If a Windows Server 2003 is
using both transports, the best practice is to use the Dell Compellent DSM and not install the Microsoft
iSCSI DSM.
4.4.1 Installing the Microsoft iSCSI DSM To install the MS iSCSI DSM, simply install the iSCSI initiator software and select Microsoft MPIO
Multipathing Support for iSCSI.
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Figure 9 Installing MS iSCSI DSM
Once installed, all iSCSI volume MPIO characteristics are controlled by the MS iSCSI DSM. Before jumping
into MPIO configuration with iSCSI it is important to understand how to connect and configure the iSCSI
initiator.
4.5 Configuring the iSCSI Initiator When using the MS DSM or the Dell Compellent DSM for iSCSI, the server must first be configured to
communicate with the Dell Compellent iSCSI front-end ports. This section describes how to configure the
iSCSI Initiator and make this connection. It assumes that the initiator software is installed, the server has
been rebooted, and the Dell Compellent Storage Center has two or more iSCSI front-end ports. In the
following examples, the server is configured with two NIC cards, each used to communicate with the
iSCSI network. To configure the connection to the Dell Compellent Storage Center:
1. Open the iSCSI Initiator.
2. Click the Discovery tab. The Discovery tab contains two sections: Target Portals and iSNS Servers.
Dell Compellent front-end ports are added as target portals.
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3. Click Add. If using virtual port mode, enter the IP address of the control port. If using legacy port
mode, enter the first primary port IP address. Do not enter reserve ports. Continue until all front-
end ports have been added.
4. Click the Targets tab. In this example there are two targets. For MPIO to function correctly, each
of the NIC cards must be logged in to each target, thus providing multiple connections to a
specific target.
5. Select the first target and click Log On.
6. Check Automatically Restore to reconnect after a reboot.
7. Check Enable multi-path.
8. Click Advanced.
The advanced options window is where each NIC card is selected to connect to the target. This
log-on sequence must be done for each IP address that communicates with the front-end port. In
this example, it is entered two times for each target. Follow the steps below to make a connection
for each.
9. Select Microsoft iSCSI Initiator from the Local adapter drop-down box.
10. Select the first IP address from the Source IP.
11. Select the Target Portal.
12. Select the necessary checkboxes for Data Digest and Header Digest.
13. Enter any Chap login information and click OK.
14. Select the same target and click Log On again.
15. Repeat steps 3-11 for each Source IP and each additional target.
In this example, there are two targets and two source IP addresses. Each IP address is logged in to
each target, creating four separate connections to the controller.
To verify:
1. Open the Dell Compellent System Manager. Create a server (if it hasn't already been created).
20 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
2. Click the server in the tree view.
3. Click the Connectivity tab. The connectivity window shows the IQN of the server and associated
controller ports (target IP addresses) that the server can see.
As seen in this example, the two Dell Compellent ports see each of the server IP addresses as
being connected (10.5.25.33 and 10.5.25.40).
The iSCSI Initiator provides another method for verification:
1. From the Targets tab in the iSCSI Initiator, select each of the targets.
2. Click Details to see that there are two connections for each of the targets.
3. Click Connections to verify that each connection is using a different source IP address.
4.6 Configuring Microsoft iSCSI DSM At this point the server and the Dell Compellent Storage Center are connected and the connectivity has
been verified. The next step is to use the Microsoft iSCSI DSM to configure the default load balance policy
for any new volumes that are mapped to the server.
To configure the default MPIO policy:
1. Open the iSCSI Initiator and click the Targets tab.
2. Select each target and click Details. Within the details section, there are two or more Identifiers.
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3. Select each one and click Connections.
4. Using the drop down menu, select an appropriate load balance policy for that connection, and
click Apply.
Note that this must be done for each connection.
To configure the MPIO policy for pre-existing volumes:
1. Open the iSCSI Initiator and click Targets.
2. Select each target individually.
3. Click Details and then Devices.
4. For each device, click Advanced.
5. In the Advanced window click MPIO.
6. Select the appropriate policy for each volume and then click Apply.
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The Microsoft iSCSI DSM offers three additional policies that are not provided by the Dell Compellent
DSM.
Least Queue Depth: The DSM routes I/O to the path with the least number of outstanding requests.
Weighted Paths: A weight is assigned to each path. The weight indicates the relative priority of a
given path. The larger the number, the lower the priority. The DSM chooses the path with the least
weight.
Least Blocks: The DSM routes requests to the processing path with the least number of pending I/O
blocks.
Note: Dell Compellent Storage Center does not support the three additional policies provided by the
Microsoft iSCSI DSM.
In conclusion, there are two methods for handling MPIO in the Windows Server 2003 operating system. If
multiple protocols are in use on the server, the Dell Compellent Multipath Manager Software must be
used. However, if iSCSI is the only transport, the Microsoft iSCSI DSM is a valid choice.
Note: Remember that both DSMs cannot be used on the same server because this will cause issues with
the MPIO stack.
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5 Using MPIO on Windows Server 2008 and 2008 R2 Windows Server 2008 and 2008 R2 have a built-in Microsoft DSM that manages all aspects of failover and
load balancing. Dell Compellent uses this DSM because it provides all the functionality required for our
customers. This also simplifies implementation, as it eliminates the need to install and maintain another
piece of software in the environment. The built-in DSM for Windows Server 2008 (and above) can manage
both iSCSI and FC volumes.
The process for mapping volumes and creating servers is identical to the process with Windows Server
2003 described in Section 3, “Configuring servers”. The rest of Section 5 covers Windows Server 2008 and
2008 R2 configuration options.
Note: Please refer to Appendix A in this document for important Windows Server 2008 and 2008 R2
MPIO configuration recommendations.
5.1 Installing the Microsoft MPIO DSM For Windows Server 2008 and above, the process of installing and configuring the Microsoft MPIO DSM
has been streamlined. A new configuration tool, the Server Manager, provides a single interface for
installing server features and roles. To access Server Manager click Start Control Panel
Administrative Tools Server Manager or click the Server Manager icon in the toolbar. There are
currently two available options for installing the DSM: the Server Manager GUI or the servermanagercmd
command line interface (CLI).
5.1.1 Server manager GUI To install using the GUI on Server 2008 and 2008 R2:
1. Open Server Manager.
2. In the tree view, click Features.
3. Check MPIO and click Next.
4. Click Install. Once the feature has been installed click Yes, if prompted, to allow the reboot.
5.1.2 Server manager CLI (2008 and 2008 R2 only) To install using the CLI, open a command prompt with elevated (administrator) privileges and type:
Servermanagercmd -install "Multipath-IO"
5.1.3 To install MPIO on Server Core: For a Windows Server 2008 Core installation, open a command prompt and type:
start ocsetup MultipathIo
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For a Window Server 2008 R2 Core installation, open a command prompt and type:
DISM /online /enable-feature:MultipathIo
Note: For server core installations, the above commands are case sensitive and must be run before the
MPCLAIM command can be used.
At this point, the Microsoft MPIO DSM has been installed but not configured. Dell Compellent volumes
must be associated with the DSM so that it can manage MPIO characteristics. The Microsoft DSM manages
all Fibre Channel and iSCSI volumes presented by the Dell Compellent Storage Center. You can choose
either or both of these transports. The built-in iSCSI initiator or an iSCSI HBA can also be used with the
same management for the iSCSI Multipath I/O.
The iSCSI initiator provides all necessary performance and stability. However, Dell Compellent supports
use of an HBA.
5.2 Associating Dell Compellent volumes with the DSM This section will describe how to associate the DSM with Dell Compellent volumes and how to setup and
configure the DSM based on the failover and load balancing policies of an organization. These instructions
assume that servers have been created in the Dell Compellent System Manager and that at least one
volume is mapped to the server via FC or iSCSI with MPIO enabled.
To associate the DSM with Dell Compellent volumes:
1. Open the MPIO control panel by clicking Start Administrative Tools MPIO.
2. Once opened, click Discover Multi-Paths.
3. Under Others, COMPELNTCompellent Vol appears.
Note: If COMPELNTCompellent Vol does not appear, rescan disk devices in Disk Management. Click on
COMPELNTCompellent Vol and then click Add. This can take a minute. When Disk Management
prompts to reboot the server, accept the prompt and allow the server to reboot. This reboot is required
to set up the association between the volumes and the DSM.
Another option for providing associations is the MPCLAIM CLI command. Open a command prompt with
elevated (administrator) privileges and type the following:
mpclaim.exe -r -i -d "COMPELNTCompellent Vol"
This command provides the same result as the Control Panel option. It associates a Dell Compellent
volume and then restarts the server. To bypass the reboot option (if rebooting later is desired), use -n in
place of the -r.
Once the server reboots, use Disk Management to verify that the configuration is correct. There should
only be one instance of each SAN volume listed in Disk Management.
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5.3 Setting the default load balance policy Once the volumes are associated, specify the default load balance policy and change any existing volumes
to use the new policy. There are some slight differences between Windows 2008 and Windows 2008 R2.
5.3.1 Windows Server 2008 default load balance policy By default in Windows Server 2008, the Dell Compellent volumes have a load balance policy of failover
only because a Storage Center is not an Asymmetric Logical Unit Assignment (ALUA) device. Unfortunately
with Server 2008, there is no way to change the default policy. Therefore, it is imperative that the policy is
changed to reflect the best practices of an organization each time a volume is mapped to the server.
The same procedure is used to change the policy on a per-volume basis with both Windows 2008 and
Windows 2008 R2.
5.3.2 Windows Server 2008 R2 default load balance policy With Server 2008 R2 and newer, a Storage Center is designated as a Round Robin device by default.
However, 2008 R2 and newer provides a method for changing the default policy system-wide as well as
on a per-volume basis.
To change the default load balance policy in Server 2008 R2, Server 2012 and Server 2012 R2, use the
MPCLAIM CLI command as follows:
mpclaim.exe -L -M <0-7> -d "COMPELNTCompellent Vol"
<0-7> refers to the desired load balance policy and shown in Table 1.
Table 1 Windows 2008 R2 Load Balance Policy
Parameter Definition
0 Clear the policy
1 Failover only
2 Round robin
3 Round robin with subset
4 Least queue depth
5 Weighted paths
6 Least blocks
7 Vendor specific
For example, to change all Dell Compellent volumes to a failover only policy, use the following command:
mpclaim.exe -L -M 1 -d "COMPELNTCompellent Vol"
Note: Failover Only and Round Robin are the only policies supported on Dell Compellent Storage Center.
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5.4 Per-volume load balance settings Now that the default policy is set, it is important to understand how to change the policy on a per-volume
basis. Some organizations may require a different policy based on the type of application or service
provided. Use Disk Management in 2008 and 2008 R2 or through the MPCLAIM utility in 2008 R2 to
change the per-volume policy. To change the policy in Disk Management:
1. Click Start Administrative Tools Server Manager.
2. In the tree view, click Storage Disk Management.
3. Right-click the disk number in the disk column and select Properties.
4. Select the MPIO tab.
5. From the drop-down box, select the appropriate MPIO policy for the volume.
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5.4.1 Using MPCLAIM in Windows Server 2008 R2, 2012 and 2012 R2 Windows Server 2008 R2, 2012 and 2012 R2 provide an enhanced MPCLAIM utility that allows the policy
to be changed on a per-volume basis much like Disk Management. The command is similar to setting the
default policy for all volumes. However, in this case the administrator chooses which volume to set.
List of all MPIO volumes on the system with the following mpclaim command:
mpclaim.exe -s –d
Figure 10 List disks with MPCLAIM
Figure 10 shows that the current policy for Disk 0 is RR (Round Robin). Use the mpclaim.exe command to
change the policy for this disk.
mpclaim.exe -L -M 1 -d 0
Refer to Microsoft TechNet for the full MPCLAIM reference guide.
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6 MPIO for Windows Server 2012 and 2012 R2 MPIO for Windows Server 2012 and 2012 R2 functions the same way as it does for 2008 R2. However,
Server 2012/R2 includes the MPIO module in Windows PowerShell®. The MPIO module is a powerful
alternative to using the MPCLAIM command. Although the MPCLAIM command is included in Server
2012/R2, Microsoft recommends using the MPIO module in PowerShell. This chapter focuses on using
the GUI and PowerShell to install and configure MPIO.
Note: On Server Core installations, please follow the instructions for PowerShell. PowerShell can be
accessed on a Server Core installation by typing powershell and pressing [Enter] at the command
prompt.
Windows Server 2012 and 2012 R2 include the ability to use heterogeneous HBA types with MPIO. In
previous versions of Windows Server, it was a requirement to use HBAs of the same model. Like Windows
Server 2008 and 2008 R2, Windows Server 2012 and 2012 R2 contain a built-in Microsoft DSM out of the
box that manages all aspects of failover and load balancing.
Note: Please refer to Appendix A in this document for important Windows Server 2012 and 2012 R2 MPIO
configuration recommendations.
6.1 Install the Microsoft MPIO feature The MPIO DSM can be installed on Server 2012 and 2012 R2 either through the GUI or through the MPIO
module in PowerShell.
6.1.1 Server manager GUI 1. Open Server Manager.
29 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
2. From the Dashboard, click Add roles and features.
3. When the Add Roles and Features Wizard window opens, click Next.
4. Select Role-based or feature-based installation and click Next.
5. Choose the local server, and click Next.
6. Without selecting a role to install, click Next on the Select server roles screen.
7. Check Multipath I/O, and then click Next.
30 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
8. Check the box to Restart the destination server automatically if required.
9. Click Install.
10. Click Close when finished.
6.1.2 Enable MPIO with PowerShell 1. Open a PowerShell window with elevated (administrator) privileges.
2. At the PowerShell prompt, type in the following command:
Enable-WindowsOptionalFeature –online –FeatureName MultiPathIO
Figure 11 Enable MPIO in PowerShell
6.2 Associate Dell Compellent volumes with the in-box DSM Now that the DSM has been installed, Dell Compellent volumes must be associated with the DSM so that
the DSM can manage MPIO characteristics. On Windows Server 2012 and 2012 R2, Dell Compellent
31 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
volumes can be associated with the DSM through the use of either the MPIO Control Panel, or through
PowerShell.
Note: Once the DSM is associated with Dell Compellent volumes, Windows will automatically claim all
Fibre Channel and iSCSI volumes presented from Storage Center and apply default MPIO settings to
those volumes.
6.2.1 Using the MPIO control panel To associate the Dell Compellent volumes with the DSM through the use of the MPIO Control Panel,
follow these steps.
1. Open the MPIO Control Panel through Server Manager, by clicking Tools and then MPIO. MPIO
can also be accessed through the Control Panel.
2. Click on the Discover Multi-Paths tab.
3. Under Others, COMPELNTCompellent Vol should be displayed.
32 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
4. Highlight COMPLENTCompellent Vol, and click Add.
5. Click Yes on the Reboot Required window.
6. Once the server has rebooted, open up the MPIO Control Panel and verify that
COMPELNTCompellent Vol is listed under Devices on the MPIO Devices tab.
33 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
7. Click OK to close the window.
6.2.2 Using PowerShell To associate the Dell Compellent volumes with the DSM through the use of PowerShell, follow these
steps.
1. Open a PowerShell window with elevated (administrator) privileges.
- On Server Core installations, type in powershell and press [Enter] at the command prompt
2. At the PowerShell prompt type:
New-MSDSMSupportedHW –VendorID COMPELNT –ProductID ‘Compellent Vol’
3. Now that Dell Compellent is supported through the Microsoft DSM, claim all available Dell
Compellent volumes to be used by MPIO by typing:
Update-MPIOClaimedHW –Confirm:$false
4. Restart the server by typing:
shutdown –r –t 0 [Enter]
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6.3 Set the Default Load-Balancing Policy Similar to Server 2008 R2, the default load balancing policy for Server 2012 and 2012 R2 is round robin.
However, the default load balancing policy can be changed system-wide or on a per-volume basis.
Storage Center supports the round robin and failover only load-balancing policies for Server 2012 and
2012 R2.
To change the default load balancing policy to failover only, open a PowerShell window with elevated
(administrator) privileges and type:
Set-MSDSMGlobalDefaultLoadBalancePolicy –Policy FOO [Enter]
Figure 12 Set default load balance policy to failover only
To change the default load balancing back to round robin, type:
Set-MSDSMGlobalDefaultLoadBalancePolicy –Policy RR [Enter]
Figure 13 Set default load balance policy to round robin
To verify the default load balance policy, type:
Get-MSDSMGlobalDefaultLoad BalancePolicy
If the default policy is set to round robin, the result will return “RR”:
Figure 14 Round robin default load balance policy
If the default policy is set to failover only, the result will return “FOO”:
Figure 15 Failover only default load balance policy
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6.4 Per-volume load balance settings Changing load balance settings on specific volumes can be done through the Disk Management GUI, or
from PowerShell.
6.4.1 Using the disk management GUI: 1. Click Start Administrative Tools Computer Management.
2. In the tree view, click Storage Disk Management.
3. Right-click the desired disk number and select Properties.
4. Select the MPIO tab.
5. From the drop-down box, select the appropriate MPIO policy (Failover Only or Round Robin) for
the volume.
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6.4.2 Using PowerShell The PowerShell MPIO module does not include cmdlets that can change the default load balancing policy
on a specific volume. Similar to Server 2008 R2, the MPCLAIM command must be used to make changes
to specific volumes.
Note: The load balancing policy cannot be changed from round robin to failover only using the
MPCLAIM command. MPCLAIM only supports switching from failover only to round robin.
To change the default load balancing policy on a single volume, open a command prompt or PowerShell
window with elevated (administrator) privileges (commands will work in both):
To list all MPIO volumes on the system, type :
mpclaim –s –d
Figure 16 Listing MPIO volumes
Figure 16 shows that the load balancing policy (LB Policy) is set to RR (round robin) for all three volumes.
The syntax to change the load balancing policy on a specific volume is:
37 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
mpclaim –l –d <disk #> <0-7>
Refer to Table 1 in section 5.3.2 for load balancing policies and the associated numbers for the mpclaim
command.
For example, to change the load balancing policy of MPIO disk 2 to round robin, type:
mpclaim –l –d 2 2 [Enter]
Figure 17 Set load balancing setting
Verify the new settings by typing:
mpclaim –s –d
Figure 18 Verifying MPIO settings
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7 Configure a Windows 2008 R2, 2012 and 2012 R2 Server
for iSCSI MPIO Windows Server 2008 R2, 2012 and 2012 R2 support MPIO with the iSCSI software initiator. iSCSI initiator
software is provided natively by the Windows Server OS.
The iSCSI quick connect feature works well for single iSCSI path connectivity. Configuring iSCSI to use
MPIO requires a few more steps, but is still easy to configure.
Figure 19 iSCSI virtual ports and domains
Figure 19 represents a dual-controller Dell Compellent Storage Center that is configured with virtual front-
end ports with 2 fault domains. Two physical iSCSI ports (one from each controller) are grouped logically
as a virtual domain that is assigned a virtual iSCSI IP address. Each virtual domain’s physical ports are
connected to two separate iSCSI switches to ensure full path redundancy to the dual iSCSI NICs on the
server.
39 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
7.1 Configuration The environment created for this configuration includes (refer to Figure 19):
Windows Server 2008 R2, 2012, or 2012 R2.
Two dedicated NIC ports (one for each fault domain) on the server for iSCSI communications.
A Dell Compellent Storage Center with dual controllers configured with virtual front-end iSCSI ports
and two virtual fault domains.
The MPIO feature installed on the server.
To configure the Server for iSCSI MPIO, complete the following steps.
1. Configure two physical NIC ports on the server to use iSCSI.
a. Configure one NIC (along with the necessary cabling and switching configurations) to access
one virtual iSCSI domain, and configure the second NIC to access the other virtual iSCSI
domain.
b. In the example shown in Figure 19, the server NICs are assigned with IPs of 10.10.95.101 (for
fault domain 100), and 10.10.128.101 (for fault domain 200).
c. Once configured, the server should be able to ping both of the virtual iSCSI IP addresses
associated with the two fault domains on the Dell Compellent Storage Center. In this example,
10.10.95.1 (fault domain 100) and 10.10.128.1 (fault domain 200).
2. Log on to the Windows server and launch the iSCSI Initiator software.
a. For Server 2008 R2, go to Start Administrative Tools iSCSI Initiator.
b. For Server 2012 and 2012 R2, start Server Manager, and from the Dashboard, click on Tools
iSCSI Initiator from the drop-down list.
Note: If receiving a prompt to start the iSCSI service (for Server 2008 R2, 2012 or 2012 R2), click
Yes.
3. Select the Discovery tab, and then click the Discover Portal button.
4. Enter the IP address of the first iSCSI target IP. In this example, the virtual iSCSI IP address
associated with the first virtual fault domain on the Dell Compellent Storage Center, and then click
Advanced.
40 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
5. From the Local adapter drop-down list, select Microsoft iSCSI Initiator.
6. From the Initiator IP drop-down list, select the local IP address of the server NIC that is to be
associated with the first fault domain (fault domain 100).
This example uses Initiator IP 10.10.95.101.
7. Click OK, and then OK again to return to the iSCSI Initiator properties window.
8. Verify that the target IP address and adapter IP address are displayed in the Target Portals window.
9. Repeat steps 3 – 8 to add the second target IP for the second virtual fault domain and the server
second iSCSI NIC (in this example, 10.10.128.1 and 10.10.128.101).
10. When completed, both pairs of iSCSI initiators and targets should be listed.
41 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
11. Select the Targets tab. This should be populated with the discovered iSCSI target ports on the Dell
Compellent Storage Center.
12. Highlight the first target, and then click Connect.
13. On the Connect To Target screen, verify that both Add this connection to the list of Favorite
Targets and Enable multi-path are checked.
14. Click Advanced to display additional options.
42 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
15. Set Local adapter to Microsoft iSCSI Initiator.
16. Select the correct IP addresses for the Target portal IP and Initiator IP from the drop-down lists.
17. Click OK, and then OK again to return to the iSCSI Initiator properties window.
18. Repeat steps 12-17 above for each additional target listed.
19. When finished, all the targets should show as Connected as shown below.
20. Click OK to exit the iSCSI Initiator properties window.
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A Windows Server MPIO configuration recommendations for
Dell Compellent Storage Center
Table 2 Recommended MPIO hotfix for Windows Server 2008 R2/SP1
KB Number Title Link
KB2871163 No warning logged when the Storport miniport driver tries to use more than 8 SCSI buses in Windows Server 2008 R2 (storport.sys – 7/13/2013)
http://support.microsoft.com/kb/2871163
KB2851144 Computer loses track of LUNs after a path failover occurs between storage controllers in Windows Server 2008 R2 or Windows Server 2012 (msdsm.sys – 6/1/2013)
http://support.microsoft.com/kb/2851144
KB2754704 A hotfix is available that provides a mechanism for DSM to notify MPIO that a particular path is back to online in Windows Server 2008 and Windows Server 2008 R2 (mpio.sys – 11/30/12)
http://support.microsoft.com/kb/2754704
KB2684681 Iscsicpl.exe process stops responding when you try to reconnect a storage device to a computer that is running Windows Vista, Windows Server 2008, Windows 7, or Windows Server 2008 R2 (msiscsi.sys – 3/9/2012)
http://support.microsoft.com/kb/2684681
Table 3 Recommended MPIO hotfixes for Windows Server 2012 (non R2 version)
KB Number Title Link
KB2867201 Stop Error 0x00000050 occurs when new StorPort features are implemented in Windows 8 or Windows Server 2012 (storport.sys – 6/29/2013)
http://support.microsoft.com/kb/2867201
KB2889784 Windows RT, Windows 8, and Windows Server update rollup: November 2013
http://support.microsoft.com/kb/2889784
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(msdsm.sys – 10/04/2013)
KB2869606 The LUN for a storage device is lost when multiple paths are lost concurrently in Windows Server 2012 (mpio.sys – 10/12/2013)
http://support.microsoft.com/kb/2869606
KB2779768 Windows 8 and Windows Server 2012 update rollup: December 2012 (msiscsi.sys – 11/6/2012)
http://support.microsoft.com/kb/2779768
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Note: All recommended registry settings apply to Windows Server 2008 R2, 2012, and 2012 R2.
Note: The maximum time allowed for Storage Center controller failover is 60 seconds. The value of
PDORemovePeriod directly correlates to this value, and thus, should never be set below 60 seconds. In
most cases, the recommended value of 90 seconds will be sufficient. In environments with failover
clusters that require faster failover times, a value of 60 can be used. System administrators are advised to
test settings on a non-production environment to make informed decisions on setting timeout values.
Table 4 Recommended MPIO Registry Settings
Location: HKLM\System\CurrentControlSet\Services\mpio\Parameters
Setting Name Description MSFT Default Value
Recommended CML Value
PDORemovePeriod This setting controls the number of seconds that the multipath pseudo-LUN remains in system memory, even after losing all paths to the device. When this timer value is exceeded, pending I/O operations will be failed, and the failure is exposed to the application rather than attempting to continue to recover active paths. The maximum time allowed is MAXULONG (49,000 days).
20 120
PathRecoveryInterval Represents the period after which PathRecovery is attempted. This setting is only used if it is not set to 0 and UseCustomPathRecoveryInterval is set to 1.
0 60
UseCustomPathRecoveryInterval If this key exists and is set to 1, it allows the use of PathRecoveryInterval.
0 1
PathVerifyEnabled This flag enables path verification by MPIO on all paths every N seconds (where N depends on the value set in PathVerificationPeriod). This Boolean function must be filled with either 0 (disable) or 1 (enable). By default, it is disabled.
0 no change
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Setting Name Description MSFT Default Value
Recommended CML Value
PathVerificationPeriod This setting is used to indicate the number of seconds with which MPIO has been requested to perform path verification. This field is only honored if PathVerifyEnabled is TRUE. This timer is specified in seconds. The default is 30 seconds. The maximum allowed is MAXULONG.
30 no change
RetryCount This setting specifies the number of times a failed I/O if the DSM determines that a failing request must be retried. This is invoked when DsmInterpretError() returns Retry = TRUE. The default setting is 3.
3 no change
RetryInterval This setting specifies the interval of time (in seconds) after which a failed request is retried (after the DSM has decided so, and assuming that the I/O has been retried a fewer number of times than RetryCount). This value is specified in seconds. The default is 1 second.
1 no change
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Table 5 Recommended Disk Registry Settings
Location: HKLM\SYSTEM\CurrentControlSet\Services\Disk
Setting Name Description MSFT Default Value
Recommended CML Value
TimeoutValue Disk time-out is a registry setting that defines the time that Windows will wait for a hard disk to respond to a command. Installing host bus adapters (HBA) or other storage controllers can cause this key to be created and configured.
60 no change
Table 6 Recommended iSCSI Initiator Registry Settings
Location: HKLM\SYSTEM\CurrentControlSet\Control\Class\{4D36E97B-E325-11CE-BFC1-
08002BE10318}\<Instance Number>\Parameters
Setting Name Description MSFT Default Value
Recommended CML Value
MaxRequestHoldTime Maximum number of seconds that requests are queued if connection to the target is lost and the connection is being retried. After this hold period, requests will be failed with "error no device" and device (disk) will be removed from the system.
60 90
LinkDownTime This value determines how long requests will be held in the device queue and retried if the connection to the target is lost. If MPIO is installed this value is used. If MPIO is not installed MaxRequestHoldTime is used instead.
15 35
TCPConnectTime Timeout given to TCP when a Connect request is sent.
15 no change
TCPDisconnectTime Timeout given to TCP when a Disconnect request is sent.
15 no change
WMIRequestTimeout Timeout value set for WMI requests such as LoginToTarget, LogoutFromTarget, SendTargets, etc.
30 no change
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Setting Name Description MSFT Default Value
Recommended CML Value
DelayBetweenReconnect If a connection is dropped while it is in FullFeature phase, the driver will attempt to re-login. This parameter sets the delay between each re-login attempts.
1 no change
MaxConnectionRetries Maximum number of times a lost TCP connection will be retried.
-1 (indefinitely) no change
MaxPendingRequests This setting controls the maximum number of outstanding requests allowed by the initiator. At most this many requests will be sent to the target before receiving response for any of the requests.
255 no change
EnableNOPOut If set to 1, the initiator will send NOP OUT PDUs to target if there is no activity for 2 minutes.
0 1
MaxTransferLength This is maximum data size of an I/O request.
262144 (256KB)
no change
MaxBurstLength This is the negotiated Max Burst Length.
262144 (256KB)
no change
FirstBurstLength This is the negotiated First Burst Length.
65536 (64KB) no change
MaxRecvDataSegmentLength This is the negotiated MaxRecvDataSegmentLength.
65536 (64KB) no change
IPSecConfigTimeout Timeout value used when the driver calls the discovery service to configure\release IPsec for an iSCSI connection.
15 no change
InitialR2T If set to Non-Zero value, initiator will request InitialR2T (InitialR2T=Yes). Else initiator will not request InitialR2T (InitialR2T=No).
0 no change
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Setting Name Description MSFT Default Value
Recommended CML Value
ImmediateData If set to Non-Zero value, initiator will request ImmediateData (ImmediateData=Yes). Else initiator will not request ImmediateData (ImmediateData=No).
1 (Yes) no change
PortalRetryCount This value is used to determine how many times a connect request to a target portal should be retried if the portal is down.
1 no change
NetworkReadyRetryCount This value is used to determine how many times initiator should retry getting the IP address of NIC corresponding to the PortNumber specified in the login request.
10 no change
ErrorRecoveryLevel Error recovery level that the initiator will request.
2 no change
AsyncLogoutPauseTimeout This is the number of seconds that the initiator pauses the I/O queue after receiving an async logout.
10 no change
Note: A reboot is required for the change to take effect. Alternatively, unloading and reloading the
initiator driver will also cause the change to take effect. In the Device Manager GUI, look under SCSI and
RAID Controllers. Right click Microsoft iSCSI Initiator and select Disable to unload the driver. Then
select Enable to reload the driver.
Sources:
Microsoft iSCSI Initiator Documentation (March 2012) - Link
Configuring MPIO Timers (September 2009) - Link
50 Dell Compellent Storage Center - Microsoft Multipath I/O Best Practices | CML1004
B Additional resources
Support.dell.com is focused on meeting your needs with proven services and support.
DellTechCenter.com is an IT Community where you can connect with Dell Customers and Dell employees
for the purpose of sharing knowledge, best practices, and information about Dell products and
installations.
Referenced or recommended Dell Compellent publications on Knowledge Center:
http://kc.compellent.com
Dell Compellent Storage Center MPIO Users Guide
Dell Compellent Storage Center Connectivity Guide
Dell Compellent Storage Center Multipath IO (MPIO) Manager for Microsoft Servers User Guide
Dell Compellent Storage Center Windows Server 2012/R2 Best Practices Guide
Referenced or recommended Microsoft publications:
Microsoft MPIO Step-by-Step Guide (2008 R2)
http://technet.microsoft.com/en-us/library/ee619778(v=ws.10).aspx
Configuring iSCSI MPIO on Windows Server 2008 R2
http://blogs.technet.com/b/migreene/archive/2009/08/29/3277914.aspx
Microsoft MPIO Users Guide for Windows Server 2012
http://www.microsoft.com/en-us/download/details.aspx?id=30450
MPCLAIM Reference Guide
http://technet.microsoft.com/en-us/library/ee619743(v=ws.10).aspx
Managing MPIO with Windows PowerShell on Windows Server 2012
http://blogs.msdn.com/b/san/archive/2012/07/20/managing-mpio-with-windows-powershell-
on-windows-server-2012.aspx
Multipath I/O (MPIO) Cmdlets in Windows PowerShell Reference
http://technet.microsoft.com/library/hh826113.aspxhttp://msdn.microsoft.com/en-
us/library/dd758814.aspx