A Guide to Using Live Migration Through Cluster Shared Volume - Updated

7/30/2019 A Guide to Using Live Migration Through Cluster Shared Volume - Updated

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ClusterSharedVolumeEffectiveVirtualMachineMigrationMohammed YasserAK

DellWindowsOSEngineering


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TableofContents

OverviewWhatisCSV?

BenefitsofCSV

RequirementsHardware

RequirementsSoftware

CreatingaCSVCreatingandConfiguringVirtualDisksonstoragearray

CreateandManageaClusterusingFailoverClusterManager

EnablingClusterSharedVolume

CreatingVirtualMachinesonCSVHyperVManagerSettingswhencreatingaVMonCSV

ConfigureVirtualMachinesServiceontheClusterVirtualMachineServiceConfiguration

LiveMigration

QuickMigration

KnownIssuesofLiveandQuickMigrationToolsandReferences


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OverviewWhatisCSV?

CSV Definition:

a) Windows 2008 R2s CSVs are shared disks in available storage (LUN) that is visible andaccessible to all nodes.

b) These shared disks appear as folders in %systemroot%\ClusterStorage folder.c) Each volume is labeled Volume1, Volume2 and so on.

Limitations in a non-CSV setup:

a) Export and Import of Virtual Machines is slow and is not automatedb) A VM cannot be moved from one host to another without interrupting services running

inside the VM.c) No failover modes to ensure availability of Virtual Machines in an event of failed Network

Link, IO or Virtualization Hosts.d) In a SAN setup, each disk or LUN is owned by a single node at any point in time, and

only that node can perform I/O to it leading to a complex setup

NTFS Reason for the above limitations:

a) NTFS is not a clustered file system and concurrent access from systems to a NTFSvolume is not allowed.b) In a failover cluster, only one node is active for a service/application, and the LUN

containing pertinent data is owned by that active node.c) If a service/application has to be moved from one node to another, the volume has to

unmounted and remounted to the new active node which would cause downtime.d) This was the only blocking factor for Live Migration feature to work on Microsoft Hyper-V


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Fig:1 NTFS Volume Access

BenefitsofCSV

How will Cluster Shared Volume help?

a) Virtual Machines are stored onto a subfolder of one of the Volumes.b) The great feature of CSV is that all nodes in the cluster can access the content of a CSV

concurrently.c) Each VM is placed in its own sub-folder of a volume which in turn enables Live Migration

to work efficiently.

How is CSV managed and used?

a) For each CSV, one node in the cluster acts as the MAIN/COORDINATOR node.b) All nodes trying to write metadata to a CSV send the metadata updates to this main node

for the volume.c) All nodes in the cluster can write normal block level information to the volume directly

which is the majority of write activity.d) CSV is actually implemented via the CSVFilter.sys file system mini-filter driver which is

responsible for the interception of the NTFS metadata requests and all I/O requests inthe event a node loses communication with the target volume.

e) A node can ask the coordinator to perform all its I/O if it can no longer communicatewith the target volume.

RequirementsHardware

CPU and Memory requirement

a) Processors should support Virtualization Technology (Intel VT or AMD-V)b) Do not mix processors from different vendors, based on different family from the same

vendor, difference in number of cores and features.


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c) Live and Quick Migration might fail when trying to migrate from newer family of aspecific processor vendor to older version

d) Have matching hardware components for best cluster performancee) Make sure all nodes have enough spare memory to take control of another VM when its

parent node fails

Storage Requirement:

a) Make sure the SAN storage array is compatible to Windows 2008 R2 Clustering Service(Refer to Microsoft website for more details on storage compatibility This is to ensurethe miniport driver used for the storage will work with Microsoft Storport storage driver)

b) Storage Arrays are configured using its respective management software like MDSM orNavisphere Utility. Test for their access from disk management before proceeding withcluster creation.

c) Storage disks that are going to be part of CSV should not be a boot or system volumed) Supported storage interfaces include iSCSI, FC and SAS

For more details on configuring SAN storage arrays from Dell refer to links below,

a) iSCSI - MD3000i Clickhere, EMC Storage Clickhere, Dell EqualLogic Storage Clickhere

b) FC Click herec) SAS Click here

Network Requirement

a) Have separate network card for storage (iSCSI) and network communicationb) SAS setup would have limitations to the number of nodes in a cluster

RequirementsSoftware

CSV Requirement:

a) Nodes that will be part of the cluster should be running the latest and same build ofWindows Server 2008 R2

Cluster Requirement:

a) Do not mix Full and Server Core Edition (Standard Edition does not support FailoverClustering)

b) Make sure all nodes are configured to connect to a domain controller and a sharedstorage (Only FC, SAS and iSCSI is supported from Microsoft)

c) Make sure the entire Cluster is validated with no errorsd) All nodes should have Failover Clustering Feature and Hyper-V Manager Role installed
http://support.dell.com/support/edocs/systems/md3000i/en/UG/HTML/index.htmhttp://support.dell.com/support/edocs/stor-sys/navisph/mgr/admingd.exehttp://support.dell.com/support/edocs/systems/clusters/Equal/en/index.htmhttp://support.dell.com/support/edocs/systems/clusters/Equal/en/index.htmhttp://support.dell.com/support/edocs/stor-sys/navisph/mgr/admingd.exehttp://support.dell.com/support/edocs/systems/md3000i/en/UG/HTML/index.htm


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Fig:2 Complete Hardware Setup


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CreatingaCSVCreatingandConfiguringVirtualDisksonstoragearray

Storage Management Software/Utility:

a) Each Storage array vendor provides a management software or utility that enablesadministrators to create and configure virtual disks from a management station

b) Make sure the firmware on the storage array is upto date to ensure compatibility withWindows Server 2008 R2

c) Storage Arrays would also require administrators to install host drivers on each nodebefore proceeding

d) In iSCSI and FC interfaces, host to virtual disk mapping has to be done using this utility.For more details, refer to the storage array manual

e) iSCSI storage would need iSCSI initiator usage on all hosts to get accessf) Use Disk Management within the Operating System to ensure the disks are listed,

initialized and in online state

g) Create partitions and format it with NTFSCreateandManageaClusterusingFailoverClusterManager

Failover Cluster Manager:

a) This feature in Windows Server 2008 onwards will help administrators build redundancyof services and applications on their network and eliminate single points of failure.

b) This helps reduce downtime, guard against data loss, and reduce total cost of ownership.c) The feature is not installed by default. It has to be added using Server Manager on all

nodes that will be part of the Cluster


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Creating a Cluster:

a) Open Failover Cluster Manager through Administrative Tools from on one of the Nodes toCreate and Manage the Cluster

b) Click on Create a cluster and it will take the administrator through below steps Select servers (Nodes) that will be part of the cluster


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The wizard would give warnings if the nodes do not meet the requirements ofbeing part of the cluster. Some warnings include;

1. The node is already part of another Cluster

2. OS types (Full and Core) do not match3. Failover Clustering service is not added on the node


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4. Node is not configured to the domain5. Node is not available or cannot be reached

The wizard will prompt the user to run the Cluster Validation Wizard that will testthe complete setup including Network, SAN and Node Configurations


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c) Review the Cluster Validation Report Any errors on the wizard will block the creation of the Cluster Warnings would still allow me to create a cluster but might impact different

failover levels on the cluster

d) Manage your cluster

EnablingClusterSharedVolume

Enabling Cluster Shared Volume and Adding disk to it

a) Refer to figure above where it shows on how to Enable CSV on a Cluster in FailoverCluster Manager.

b) Add available storage to the CSV using the option of Add Storage. There should beenough available storage to be added to the CSV. You cannot add storage assigned forDisk Quorum Settings


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c) Check Disk Management on all nodes and you would see the state changed to Reserved

d) On Failover Cluster Manager, check for the current owner of the CSV. This is theActive/Coordinator Node I was referring to in the beginning of the article


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CreatingVirtual

Machines

on

CSV

HyperVManagerSettingswhencreatingaVMonCSV

Node Configuration:

a) Make sure Hyper-V Role is added on all the Nodes using Server Managerb) Name for Virtual Network Switch on all Nodes should be the same

Virtual Machine Configuration:

a) If pass-through disks are configured for a specific VM on a node, make sure the disk ison the same network as other nodes

b)

Make sure Integration Components are installed on all the guest Operating Systems


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c) Mapped network drives and Image files should be on the same network as other nodesd) Virtual Machine Configuration Settings and respective VHDs to be stored on the

C:\ClusterStorage\Volume path


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e) Make sure Remote Desktop is enabled on all the Virtual Machines for purpose of testingLive Migration

f) Test for Virtual Machine functionality through Remote Desktop from another client

ConfigureVirtual

Machine

Service

on

the

Cluster

VirtualMachineServiceConfiguration

Prerequisites:

a) Before configuring Virtual Machine Service to the cluster, make sure the above stepswere considered while creating the Virtual Machine

b) Turn off all the virtual machines that you intend to add to the cluster


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Adding Virtual Machine Service:

a) Click on Configure a Service or Application under the cluster you had created

b) Select Virtual Machine and Click on Nextc) A small validation check is performed in the background to check if all the nodes on the

cluster have Hyper-V Role added and they share the same Hypervisor version


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d) If VMs are in the running state, the wizard will display an error as below;

e) It will list all virtual machines on the cluster and prompt the user to selectf) Once selected, it will validate every virtual machine and generate a report


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g) Report would have warnings or errors if any of the steps mentioned above for VMcreation wasnt followed

Virtual Machine Summary and Ownership Details:

a) Each Virtual Machine Properties will provide settings for configuring Failover and settingpreferred owners


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b) Virtual Machines can be managed directly from the Failover Cluster Managerc) Administrators will also have the option to manually perform Live or Quick Migration of

Virtual Machines if a planned downtime is set for any node


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LiveMigration

Definition:

a) This is a process that can be initiated by user or be automatic in event of failure whereinthe VM state and settings are migrated from one node to otherb) Users or Clients accessing the VM will still be having access to the VM during this process

c) Slower than Quick Migration but is seamlessSteps Involved:

a) Scenario: The complete hardware and VM setup is shown as below with three VMs beinghosted by Node 1 on the Cluster.


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b) Step 1: For migrating VM2 hosted by Node1 to Node2, the process first starts of withcreating and transferring a full memory copy of the current VM state

c) Step 2: After this, Dirty pages of memory that include the current changes/process onVM starts getting copied


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d) Step 3: Cluster Manager should show the Migration to be complete and the respectiveVM host ownership would be changed to Node 2

During all of the above, the Remote Client/User has still access to the VM and applications on itwithout any interruption.

QuickMigration

Definition:

a) This is a process that can be initiate by user wherein the VM goes into a Saved stateb) Users or Clients accessing the VM will temporarily lose access to the VM till the migration

is completec) Much faster than Live Migration and best suited when the node that is hosting the VM

has a planned downtime or when migration was planned


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KnownIssuesofLiveandQuickMigrationError 1: VM Migration between Intel and AMD Error Message:

Reason: Working as designed

Workaround: Do an Export and Import of Virtual Machine (Move VMs through Failover ClusterManager) instead of Quick and Live Migration

Error 2:

VM Migration between different families of same processor vendor of different families may fail

Reason: Working as designed

Workaround: Enable Migration through processors where features do not match on the Virtual

Machine Processor Setting. Please note this process is not reversible.


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ToolsandReferenceshttp://www.microsoft.com/virtualization/default.mspx
http://www.microsoft.com/virtualization/default.mspxhttp://www.microsoft.com/virtualization/default.mspx

Documents

A Guide to Using Live Migration Through Cluster Shared Volume - Updated