This is a white paper that my buddy Aayush Bhatt and I wrote on Storage Migration using System Center 2012 R2 Virtual Machine Manager & Hyper-V on Windows Server 2012 R2 in Microsoft Private Cloud
In order to migrate the physical storage underneath the Fabric and Tenant environments of a Microsoft System Center 2012 Private Cloud, we need to consider several components of the Storage layer i.e. Boot LUNs, Storage LUNs, Quorum disk witness, Cluster Shared Volumes (CSV) etc.
Following is the high level overview of the Storage Migration plan.
Storage LUN
Boot LUN
Quorum Disk
Storage LUNs are used to save virtual machine hard disk files (.VHD and .VHDX), virtual machine configuration data files and snapshots etc. Typically, storage LUNs are usually converted to Cluster Shared Volumes (CSV), which in turn are shared by Hyper-V hosts in the cluster.
The process that happens behind the scenes while performing VM storage migration using SCVMM is as follows.
Using Microsoft System Center 2012 R2 Virtual Machine Manager with Hyper-V on Windows Server 2012 R2 provides you the functionality to live migrate the storage of a stand-alone virtual machine without any downtime. In case of Clustered VMs, or any virtual machines which have shared virtual hard disks, a downtime is required. The details of both the scenarios are described below.
Stand-alone virtual machines are those VMs which have their own VHDs and are neither clustered, nor have a shared VHD. These machine can be migrated without any downtime using the straight forward migration approach of SCVMM. Its process is as follows:
Second scenario includes virtual machines which are either clustered on Hyper-V hosts or have virtual hard disk attached to it which is shared among two or more virtual machines. Migration of such kind of virtual machines requires downtime as the shared drives needs to be removed before migrating the VM storage. Its process is as follows:
Boot LUNs are attached to the physical Hyper-V hosts and contains booting configuration data of the host. Unlike storage LUNs, these are not shared and each host has one Boot LUN attached to it.
Migrating the Boot LUN of a Hyper-V hosts requires the host to be shut down. In case of a Hyper-V host clustering environment, we can live migrate all the virtual machines from one host to another host(s) before shutting it down, thus preventing any downtime. But if, Hyper-V hosts are not clustered, then the virtual machines running on top of the Hyper-V hosts needs to be shut down in order to perform the activity.
The quorum configuration in a failover cluster determines the number of failures that the cluster can sustain. If an additional failure occurs, the cluster must stop running. A Quorum is a Disk Witness which contains a copy of the cluster configuration.
The process of migrating Quorum disk is as follows:
Monitor the cluster by checking event logs etc.