86373-05A-1-5_VSS_HW_Provider_UG

Hardware Provider for Microsoft Volume Shadow Copy Service (VSS) User Guide

Part No. 0086373-05A

Issue 1.5

February 9, 2009

NoticesThe information in this document is subject to change without notice.

While every effort has been made to ensure that all information in this document is accurate, the Authors accept no liability for any errors that may arise.

No part of this document may be transmitted or copied in any form, or by any means, for any purpose, without the written permission of the Authors.

Acknowledgments

Issue 1.5 February 9, 2009 Part No. 0086373-05A

Hardware Provider for Microsoft Volume Shadow Copy Service (VSS)

• Microsoft is a registered trademark of Microsoft Corporation.

• All other names, brands, products or services are trademarks or registered trademarks of their respective companies.

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Table of Contents

ContentsPreface ................................................................................................................................................... v

Related Documentation .......................................................................................................................... v

Revision History ..................................................................................................................................... vi

1 Introduction ..................................................................................................................................... 11.1 Overview ..................................................................................................................................... 1

1.1.1 Theory of Operation ........................................................................................................... 11.2 System Requirements ................................................................................................................. 2

1.2.1 Enclosures .......................................................................................................................... 21.2.2 Hardware ............................................................................................................................ 21.2.3 Software ............................................................................................................................. 2

1.3 Installation ................................................................................................................................... 21.3.1 Verifying the Installation ..................................................................................................... 3

1.4 Uninstallation ............................................................................................................................... 3

2 Using VSS ........................................................................................................................................ 52.1 Setup Requirements .................................................................................................................... 52.2 Usage .......................................................................................................................................... 6

2.2.1 Creating a Snapshot ........................................................................................................... 62.2.2 Listing Snapshots ............................................................................................................... 62.2.3 Exposing a Snapshot ......................................................................................................... 72.2.4 Example of Use .................................................................................................................. 7

3 Known Issues and Limitations ...................................................................................................... 93.1 Enclosure Logical Drives versus Windows Volumes ................................................................... 93.2 Licensing of the Snapshot Technology ..................................................................................... 103.3 Use of VSS tools ....................................................................................................................... 103.4 Breaking a snapshot set ............................................................................................................ 103.5 Maximum Number of Concurrent Shadow Copies .................................................................... 103.6 HBA Limitations ......................................................................................................................... 113.7 Disks Initialized with GPT .......................................................................................................... 113.8 F5404E Limitation ..................................................................................................................... 123.9 Upgrading or Downgrading from VSS Hardware Provider 0.73 ................................................ 123.10 Creating Snapshots After Deletion of Previous Snapshots ....................................................... 12

4 Troubleshooting ............................................................................................................................ 134.1 Problems Creating Snapshots ................................................................................................... 134.2 Provider Service is not Started .................................................................................................. 13

5 Event Log Messages ..................................................................................................................... 155.1 Introduction ................................................................................................................................ 155.2 Successful Messages ................................................................................................................ 155.3 Informational Messages ............................................................................................................ 155.4 Warning Messages .................................................................................................................... 165.5 Error Messages ......................................................................................................................... 16

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iv

Preface

PrefaceWhat is in this guideThis user guide gives you an overview of how to use the Hardware Provider for Microsoft Volume Shadow Copy Service (VSS) and any issues to be aware of when using the provider.

Who should use this guideStorage managers and software testers who need to make point-in-time copies of data from supported Xyratex enclosures via Microsoft Volume Shadow Copy Services (VSS).

About this guideThis user guide provides the following information:

• Chapter 1, ”Introduction,” on page 1 gives an overview, system requirements and installation instructions.

• Chapter 2, ”Using VSS,” on page 5 shows how the provider is used in conjunction with Microsoft Volume Shadow Copy Service.

• Chapter 3, ”Known Issues and Limitations,” on page 9 lists any issues which may affect use of the software.

• Chapter 4,, ”Troubleshooting,” on page 13 provides resolutions for some common problems.

• Chapter 5,, ”Event Log Messages,” on page 15 lists all of the events and associated code numbers that may appear in the event log.

Related DocumentationThe following documentation is essential for the understanding and use of this software:

• Official Microsoft documentation for VSS:

http://www.microsoft.com/windowsserversystem/storage/storservices.mspx

• The Microsoft VSS Technical Reference:

http://technet2.microsoft.com/windowsserver/en/library/2b0d2457-b7d8-42c3-b6c9-59c145b7765f1033.mspx?mfr=true

• The Microsoft VSS Software Development Kit:

http://www.microsoft.com/downloads/details.aspx?FamilyID=0B4F56E4-0CCC-4626-826A-ED2C4C95C871&displaylang=en

The following documentation may also be useful:

• StorView Storage Management Software RAID Module User Guide (part number: 0094089).

• Xyratex Command Line Interface for RAID (XCR) User Guide (part number: 0084353).

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Revision History

Version Date Description of Change

1.0 August 28, 2007 Initial Release

1.1 February 1, 2008 Additional known issues and limitations

1.2 July 9, 2008 Support for Windows Server 2008, additional known issues and limitations

1.3 August 22, 2008 Minor updates.

1.4 January 5, 2009 Added support for F6500E controller.

1.5 February 9, 2009 Added licensing information and new error messages. Removed concurrent snapshot problem from Known Issues section (resolved).

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Introduction

Chapter 1

Introduction

1.1 OverviewVolume Shadow Copy Service (VSS) is a feature in Microsoft Windows Server. It allows backups to be made while maintaining 24/7 access to a storage subsystem (the storage does not have to be taken off-line while backups are made). Each vendor of a storage solution can write their own “provider” that enables VSS to be used with their storage device.

The Xyratex Hardware Provider for VSS enables the Microsoft Volume Shadow Copy Service to be used with the RAID controller enclosures listed in 1.2.1 on page 2.

1.1.1 Theory of OperationWhen setting up a system that makes use of the snapshot feature, you must create two separate arrays. One of these arrays holds the logical drive that contains the user’s data and is available as a standard volume within Windows. The second array is used to hold the snapshot data. Snapshot data is the data copied from the user volume at a specific point in the past.

When enabling the snapshot feature using StorView on the logical drive holding the users data, an area of the second array must be chosen. This will hold the snapshot data and will be made into an internally available logical drive. A special area is created on it called the Overwrite Data Area (ODA). This area is not available for normal use by any hosts connected to the system – it is reserved purely for snapshot purposes.

When a snapshot is initiated using a Windows requester such as the Backup Utility, the following happens:

• I/O is temporarily frozen and cached data is written to the originating volume.

• VSS asks any registered providers if they support all of the parts of the selected volume. If a VSS provider responds in a positive way then VSS commands the provider to start a snapshot.

• A command is then sent to the enclosure to tell it to perform the snapshot. All subsequent writes to the originating volume will cause the data that is about to be overwritten to be copied to the snapshot area.

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• After the snapshot has completed successfully, VSS waits for the Plug-and-Play device manager to recognise that a new device has arrived. This new device is the snapshot itself. This will be hidden to the user but can be exposed and used as a standard read-only volume at some future time. This allows the user to see the volume as it was at the time of the snapshot and map it as a physical volume within the operating system.

1.2 System Requirements

1.2.1 EnclosuresThe following enclosures and RAID Controllers are supported:

• RS-1220-F4-5402E (F5402E)

• RS-1220-E3-5402E (E5402E)

• RS-4835-F4-5404E (F5404E)

• RS-1220-F4-5412E (F5412E)

• RS-1220-E3-5412E (E5412E)

• RS-1220-F4-6412E (F6412E)

• HB-2435-F8-6500E (F6500E)

• HB-2435-E311-XPN (F6500E)

1.2.2 HardwareThe following hardware is required:

• A Host Bus Adapter (HBA).

• A direct connection from the HBA to the enclosure.

1.2.3 SoftwareThe software must be installed on one of the following operating systems:

• Microsoft Windows Server 2003 with Service Pack 2 (Web, Standard, Enterprise, Enterprise 64-bit and Standard 64-bit).

• Microsoft Windows Server 2008 (32-bit, 64-bit and IA64).

1.3 InstallationUse the following procedure to install the Xyratex Hardware Provider for VSS:

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Introduction

1 Double-click the installer executable, which will have a name in the form “VSS Hardware Provider - Xyratex 0.0.x.xx.exe.”

2 Read the license agreement and click I Agree to accept to the terms and conditions.

3 Choose a destination folder for the application (or accept the default) and click Install.

4 You will be informed once the installation is finished. Click Close to dismiss the installation window.

1.3.1 Verifying the InstallationTo verify that the installation has performed all tasks successfully:

1 Click “Start -> All Programs -> Administrative Tools -> Services”

2 In the Services window there should be a service called “Xyratex VSS Provider”. The “Startup Type” should be set to “Automatic”.

3 Start a Command Prompt window and type following:

vssadmin list providers

4 A service called “VSS Hardware Provider - Xyratex” should be present in the output from the command.

5 If the tests in steps 2 and 4 pass, the provider has installed correctly.

1.4 UninstallationAn uninstallation executable is provided in the “Program Files \ VSS Hardware Provider - Xyratex” folder.

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4

Using VSS

Chapter 2

Using VSS

2.1 Setup RequirementsImportant Before using the Xyratex VSS provider to create shadow copies, it is essential that the following

steps are performed.

Using StorView:

Note These steps can also be performed using an alternative method, such as the controller’s TUI.

1 Create two arrays of any RAID level.

2 Create at least one logical drive on the first array.

3 Create a SAN LUN mapping for each logical drive.

Important The Xyratex VSS provider cannot operate without SAN-mapped logical drives. To enable the SAN LUN mapping feature, a valid license must be applied. This can be done using StorView or XCR (see ”Related Documentation” beginning on page v.)

4 Once the arrays have finished initializing, select each of the logical drives and Enable Snapshot. Select space on the second array for the snapshot data (ODA Size). It is suggested this is at least the same size as the logical drive to be protected.

Using Windows:

5 Open Disk Management from within the Computer Management application that comes with Windows Server. If the logical drives cannot be seen, use the “Action -> Rescan Disks” menu item to detect them.

6 Initialize each of the new disks.

7 Add partitions to the initialized disks.

8 Create logical drives on the partitions. Make sure drive letters are assigned and the drives are formatted with the NTFS file system.

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It should now be possible to create snapshots on the Windows drives located on the enclosure using the VSS provider.

2.2 UsageThere are a number of applications that can communicate with VSS.

The following will not use the hardware provider – they are configured to use an internal software provider:

• The vssadmin utility.

• The Shadow Copy tabs in Windows Explorer’s Properties window.

The applications recommend for using the hardware provider are:

• The vshadow command, which can be found in the following place:

• For Windows Server 2003: The Microsoft VSS Software Development Kit.

• For Windows Server 2008: The Windows Software Development Kit for Windows Server 2008.

• The diskshadow command (in Windows Server 2008 only).

• The Microsoft Backup application (found under the “Accessories > System Tools” menu).

2.2.1 Creating a SnapshotTo issue a simple snapshot, type the following command:

vshadow -p <Drive Letter>

Where:

• –p – Creates a persistent snapshot which can be viewed in StorView.

• <Drive Letter> – The Windows label for a drive located on the Xyratex enclosure.

For example:

vshadow –p F:

Note If the –p is omitted, vshadow will cause the snapshot to be deleted at completion of the command.

2.2.2 Listing SnapshotsTo list all snapshots known to the system, type:

vshadow –q

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Using VSS

2.2.3 Exposing a SnapshotTo expose a snapshot as a drive (making its contents available as if it were any other drive) type:

vshadow –el=<Snapshot ID>,<Drive Letter>

Where:

• <Snapshot ID> – The identifier for the snapshot, including the braces: {}. This can be determined using the “vshadow -q” command.

• <Drive Letter> – The Windows label for accessing the snapshot data.

The data will only be available to read, not to write.

For example, to expose the snapshot with ID {6a1c4c9d-3fd7-48dc-adfa-a35d1064f9f9} as drive letter G:

Vshadow –el={6a1c4c9d-3fd7-48dc-adfa-a35d1064f9f9},G:

2.2.4 Example of Use

1 Create a logical drive on the enclosure that can be snapshotted. This will be assigned a drive letter, say D:.

2 Store some files on this drive.

3 Create a persistent snapshot by typing:

vshadow -p D:

4 Query all snapshots in the system and make sure that the command has completed successfully by typing:

vshadow -q

The output should look similar to the following:

Querying all shadow copies in the system ...* SNAPSHOT ID = {8fe7374f-c226-4516-b264-807b8fb5c042} ... - Shadow copy Set: {fd10e62b-ad4f-41ab-b5dc-f7156acd4336} - Original count of shadow copies = 1 - Original Volume name: \\?\Volume{06542530-17f6-11dc-ac00-0016763eb177}\ [D:\] - Creation Time: 11/06/2007 13:50:05 - Shadow copy device name: \\?\Volume{0654253c-17f6-11dc-ac00-0016763eb177} - Originating machine: BlueBook - Service machine: BlueBook - Not Exposed - Provider id: {6a1c4c9d-3fd7-48dc-adfa-a35d1064f9f9} - Attributes: No_Auto_Release Persistent Hardware

5 Delete some of the files from D:.

6 Expose the snapshot as, say E: by typing:

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vshadow –el={8fe7374f-c226-4516-b264-807b8fb5c042},E:

7 You can now retrieve the deleted files. At this point, the E: drive has the same contents that the D: drive did at the point of the snapshot.

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Known Issues and Limitations

Chapter 3


3.1 Enclosure Logical Drives versus Windows VolumesOne area that can cause a degree of confusion is the difference between a Logical Drive created on the enclosure and a Volume created within Windows. These are conceptually very different. Windows volumes are created using some or all of the space taken up by a Logical Drive. This can be a problem if using Volume Shadow Copy Services and StorView together, as in the following example.

• A logical drive of 200 GB is created and mapped on the enclosure.

• The user now creates two volumes with Window’s Disk Management, each of 100 GB. These are assigned the drive letters D: and E:.

• The logical drive has snapshot enabled, which means both D: and E: are covered by a single snapshot or shadow copy command.

• The user uses D: and E: independently creating shadow copies whenever necessary.

D:(100GB)

LogicalDrive

(200GB)

E:(100GB)

Enclosure

Windows

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• At some point the user has a problem with D: and decides to recover the D: drive using StorView’s Snap Back feature as he does not want to individually recover files using VSS.

• This could cause a potential data loss as the Snap Back initiated by StorView will recover the whole of the logical drive to a specific point in time. This means both D: and E: will be returned to that point in time and updates to E: could be lost.

Therefore, great care must be taken when using the StorView Snap Back facility in Windows.

3.2 Licensing of the Snapshot TechnologyThe default licensing for the controller firmware limits the number of snapshots that can be created. By default, only one ODA can be created and this one ODA is limited to four snapshots. To access the maximum number of supported ODAs and snapshots requires issuing a license key through StorView to the controller. See the StorView documentation for details on how to issue a license.

3.3 Use of VSS toolsThe vssadmin utility and the Shadow Copy tabs in Windows Explorer’s Properties window cannot be used with this VSS Hardware Provider. This is a limitation of Microsoft’s implementation of VSS rather than an issue with the provider.

3.4 Breaking a snapshot setIt is possible to break a previously created snapshot from VSS using commands such as:

vshadow –b {snapshot set ID}

or:

vshadow –bw {snapshot set ID}

This separates the snapshot from VSS and the operating system subsequently treats it as a volume. This will work using the VSS Hardware Provider but is not recommended. Particularly, using a previously created snapshot as a standalone writable volume is strongly discouraged.

3.5 Maximum Number of Concurrent Shadow CopiesThe maximum number of shadow copies that can be created simultaneously is currently 4.

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For example, the following command would be acceptable:

vshadow -p e: f: g: h:

… but the following is not allowed:

vshadow -p e: f: g: h: i:

If more than 4 shadow copies are attempted at once a timeout error will be reported by Windows. They will be created successfully on the enclosure but Windows will be unaware of them.

If large numbers of shadow copies are required, they should made in batches of no more than four at a time.

3.6 HBA LimitationsSome HBAs impose a limitation of 256 LUNs for each FC port (in other words, LUNs 0-255 will be visible to the HBA, but LUNs of 256 and greater will not). Since each snapshot requires a new LUN, this can result in a situation where the HBA (and therefore Windows) will not see snapshots.

3.7 Disks Initialized with GPTA “VSS_E_NO_SNAPSHOTS_IMPORTED” error may be encountered in the following circumstances:

• An attempt is made to take snapshots on two or more mapped Windows volumes in a single snapshot command.

• The disks on which the volumes reside have been initialized using GPT (GUID Partition Table) rather than MBR (Master Boot Record).

This is a Windows issue, with a hotfix described by Microsoft in the following article:

http://support.microsoft.com/kb/932532

The hotfix must be obtained by sending a request to Microsoft Online Customer Services.

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3.8 F5404E LimitationWhen issuing a multi-volume VSS snapshot command on a RS-4835-F4-5404E enclosure, for example:

vshadow -p E: F: G:

… there is a possibility of the VSS service failing with a VSS_E_HOLD_WRITES_TIMEOUT error.

To avoid this, include only one OS volume per VSS snapshot command when using RS-4835-F4-5404E enclosures, for example:

vshadow -p E:vshadow -p F:vshadow -p G:

3.9 Upgrading or Downgrading from VSS Hardware Provider 0.73When attempting to upgrade to, or downgrade from, VSS Hardware Provider 0.73, and error message in the form “Error opening file for writing” may be seen.

In order to avoid this, use the “Uninstall” option rather than the “Upgrade” or “Rollback” options. Once the provider has been uninstalled, you can install the desired version in the normal way.

3.10 Creating Snapshots After Deletion of Previous SnapshotsSometimes when a snapshot is deleted, subsequent creation of a snapshot can cause a “VSS_E_NO_SNAPSHOTS_IMPORTED” error.

This occurs because the Device Manager is not performing a refresh of the device list after deletion of the snapshot. As a workaround, perform a manual Device Manager rescan after deleting a snapshot.

This problem can also occur if snapshot creation is attempted on a volume which already has the maximum number of allowed snapshots.

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Troubleshooting

Chapter 4

Troubleshooting

4.1 Problems Creating SnapshotsIf you are having trouble creating snapshots try the following:

1 Check the Application section of the Windows Event Log for any Xyratex VSS Provider messages – see ”Event Log Messages” beginning on page 15.

2 Check that snapshot is enabled on the logical drive holding your data.

3 Check that the logical drive holding your data is mapped using the SAN Mapping option in Storview.

4 Check that the Windows volume is formatted.

5 The specific system configuration may be the cause of the problem – see ”Known Issues and Limitations” beginning on page 9.

Note The hardware provider does not work with the vssadmin command or the Shadow Copy tabs in Windows Explorer’s Properties window. These are hard-wired to the Microsoft’s software provider.

If the problem still cannot be resolved, contact your storage vendor.

4.2 Provider Service is not StartedThe Xyratex VSS Hardware Provider service is started on demand. Therefore it will not appear as “Started” in the list of Windows Services until commands or programs are issued that require it.

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Event Log Messages

Chapter 5

Event Log Messages

5.1 IntroductionThe Xyratex VSS Hardware Provider stores messages in the Application section of the Windows Event Log. The errors and their meanings are detailed in the following section.

5.2 Successful MessagesThese messages indicate successful completion of a command.

5.3 Informational MessagesThese messages are purely for information and require no intervention on the part of the user.

Event Log Message Explanation

Shadow copy created successfully The shadow copy has been created successfully on the enclosure. No action is required.


Starting provider and loading into memory

The provider has been started successfully.

Stopping provider and unloading from memory

The provider has been stopped successfully.

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5.4 Warning MessagesThese messages warn of situations that may require intervention.

5.5 Error MessagesThese messages indicate that a problem has occurred and requies attention.


No ODA assigned to the selected logical drive. Has Snapshot been enabled on this LD?

The snapshot has not been enabled using Storview. Enable the snapshot on the chosen Logical Drive.

Overwrite Data Area (ODA) is 80% Full The amount of space available for snapshots on this logical drive is now 80% full. No action is required but it may be necessary to perform some housekeeping.

Overwrite Data Area (ODA) is 95% Full The amount of space available for snapshots on this logical drive is now 95% full. It is recommended the user performs some housekeeping.


Unable to read Controller information to determine if the LUN can be shadow copied

Communication problem. Check the connections and retry the command.

The controllers do not support shadow copy (snapshot). Please check firmware has a valid license

Check that appropriate snapshot licensing is available for the RAID controller firmware installed.

Unable to determine which Logical Drive matches this LUN


Unable to read Overwrite Data Area (ODA) information from the controller to determine if the logical drive can be shadow copied


Unable to read Overwrite Data Area (ODA) stats information from the controller to determine if the logical drive can be shadow copied


Unable to read configuration information from the controller to determine if the logical drive is mapped


SAN Mapping does not appear to have been setup for this logical drive. Please add mappings before continuing

SAN mapping must be applied to the Logical Drive in order for it to be shadow copied. Please add an appropriate mapping before continuing.

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Event Log Messages

Unable to perform a shadow copy as the maximum number supported by the controller has been reached

The user has reached the maximum number of snapshots they have a license for. Contact provider for a license key.

Unable to perform shadow copy as the Overwrite Data Area (ODA) is invalid or full

Space available for snapshots is now full and potentially invalid. Delete all snapshots to continue.

Device does not match any previously discovered devices


Unable to allocate memory for current configuration structure within LocateLuns()

Internal provider memory error. Using Window Services, stop the Xyratex VSS Provider and restart it. Retry the command.

Unable to create mapping for shadow copy (start new config)


Unable to create mapping for shadow copy (Delete mapping failed)


Unable to create mapping for shadow copy (Add mapping failed)


Unable to create mapping for shadow copy (Save config failed)


Unable to delete snapshot Communication problem. Check the connections and retry the command.

Unexpected snapshot set ID during EndPrepareSnapshots

Internal Microsoft Windows VSS Problem. Using Window Services, stop the Xyratex VSS Provider and restart it. Retry the command.

EndPrepareSnapshots called out of sequence


Unexpected snapshot set ID during PreCommitSnapshots


PreCommitSnapshots called out of sequence


Unexpected snapshot set ID during CommitSnapshots


CommitSnapshots called out of sequence



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Failed to create a shadow copy of the chosen logical drive


Unexpected snapshot set ID during PostCommitSnapshots


PostCommitSnapshots called out of sequence


Unable to allocate memory for current configuration structure in FindLunUsingLunReference()


Unsupported Operating System detected during GetTargetLuns

The provider only supports Windows Server 2003 and Windows Server 2008.

Timed out waiting for deletion of shadow copy to complete


One or more snapshots could not be taken. Timed out waiting for controller to come out of busy state


One or more snapshots could not be taken. Timed out waiting for controller to return successful status


Unable to read the snapshot data Communication problem. Check the connections and retry the command.

Unable to read Configuration In Progress information from the controller


Unable to determine if async API is supported


Unable to determine match for VDS LUN INFO identifier for mapping of shadow copy


Unable to read license information Unable to retrieve the license information from the controller. Problems communicating with the controller.

Unable to import the snapshot because the source Logical Drive is not SAN LUN mapped to the host

The snapshot belongs to a logical drive that is not SAN LUN mapped. Logical drives must be SAN LUN mapped for snapshots to be imported successfully to the host.


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Documents

86373-05A-1-5_VSS_HW_Provider_UG