This will make your cluster work quicker. Additionally, CSV enables Live Migration which allows you to move a running VM from one node to another node with zero downtime. Since disk ownership no longer needs to change when a VM moves to another node, this makes the process quicker and safer, allowing clients to remain connected while the virtual machine is moved to another node in the cluster. The CSV disk resource which is owned by a cluster node is called as coordinate node. The VMs which are hosted on the CSV disk can be owned by either coordinated node or any other node of the cluster. When a disk is in the available storage group, it can be converted to CSV. When a CSV disk is created in the Failover Cluster, internally, a hidden role will be created by the failover cluster which is not visible in the Failover Cluster GUI, but visible through cluster.exe command output. Only CSV disk is shown in the Failover Cluster GUI. The name of the CSV role is in the form of a GUID. For every highly available VM created on the CSV, there will be a role created in the Failover Cluster which is independent of the CSV role. The following screenshot has two virtual machines created on a single CSV Disk. For each virtual machine there is a role created.

In a multi-site storage array replicated environment, CSV disks are replicated to the remote datacenter using the array based remote replication feature. VMs residing in the CSV disk can run on any cluster nodes (physical servers). In case of disaster to the primary datacenter, CSV disks need to be brought online in the secondary datacenter. For this, storage failover needs to be done after checking the CLX disaster recovery rules before cluster brings the CSV disk online. This is where CLX comes into picture to swap replication direction and perform the storage failover in an automated fashion to add failover capabilities for the CSV disks in the clustering environment.

3PAR Cluster Extension supports CSV disk on Windows Server 2012 in addition to non CSV disk support. Configuration of CSV disk for CLX is similar to configuration of normal disk for CLX support. Since the CSV role is hidden and not seen in Failover Cluster GUI, CLX has provided PowerShell Cmdlets to configure Cluster Extension 3PAR resource for the CSV disk. See “Cluster Extension Cmdlets for CSV and Virtual Machine Management” (page 58) on how to configure CSV disk for CLX.

14 HP 3PAR Cluster Extension features