What Is Cluster Shared Volume and Its Functions/Technical Skills? [MiniTool Wiki]
What Is Cluster Shared Volume?
Cluster Shared Volume (CSV) is a shared disk containing an NTFS or ReFS (ReFS: Windows Server 2012 R2 or newer) volume accessible for read/write operations by all nodes within a Windows Server Failover Cluster. It is a feature of Failover Clustering that was first introduced in Windows Server 2008 R2 for use with the Hyper-V role.
What Are the Functions of Cluster Shared Volume?
A Cluster Shared Volume enables a virtual machine (VM) complete mobility throughout the cluster as any node can access the VHD (virtual hard disk) files on the shared volume. It simplifies storage management by permitting large numbers of VMs to be accessed off a commonly shared disk.
Also, a Cluster Shared Volume increases the resiliency of the cluster by having I/O fault detection and recovery over alternate communication paths between the nodes in the cluster. While CSV isn’t required for Live Migration of VMs, it reduces the potential disconnection period at the end of the migration since the NTFS file system doesn’t have to be unmounted/mounted as is the case with a traditional cluster disk.
That helps ensure seamless live migration since the physical disk resource doesn’t need to be moved between nodes. Thus, Cluster Shared Volume increases the chance that live migration will complete within the TCP reconnect window and ensure a seamless operation to clients.
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To make use of cluster shared volume, a HyperV VM is configured and the associated virtual hard disks are created on or copied to a CSV disk. Multiple VHDs can be placed on a CSV that in turn are associated with multiple VMs which can be running on different nodes in the cluster.
How Does Cluster Shared Volume Work?
Cluster Shared Volume operates by orchestrating metadata I/O operations between the nodes in the cluster via the Server Message Block (SMB) protocol. The node with ownership of the LUN (Logical Unit Number) orchestrating metadata updates to the NTFS volume is referred to as the Coordinator Node.
Read and write operations are passed directly to the Serial attached SCSI, iSCSI, Fibre Channel, or Fibre Channel over Ethernet shared storage via block-based protocols. Cluster Shared Volume builds a common global namespace across the cluster using NTFS reparse point. Volumes are accessible under the %SystemDrive%\ClusterStorage root directory from any node in the cluster.
Cluster Shared Volume can be enabled in the Failover Cluster Manager MMC snap-in by selecting “Enable Shared Volume” from the info pane after creating a cluster. Additionally, CSV can be enabled using PowerShell with the following command:
(Get-Cluster [-Name <cluster Name>]).EnableSharedVolume="Enabled"
For more details about Cluster Shared Volume, please refer to: