Storage Replication; Hyper-V Quick Migration; Hitachi Storage Cluster Solution - Hitachi Adaptable Modular Storage 2000 Best Practices Manual

Storage Replication

Another important part of protection strategy is storage replication. The 2000 family has built-in storage
replication features such as ShadowImage Replication software and Copy-on-Write that can provide rapid
recovery and backup in a Hyper-V environment. As more and more child partitions are placed on a physical
Hyper-V server, the resources within the Hyper-V server might become constrained, thus affecting the backup
window. By using solutions such as ShadowImage Replication software on 2000 family storage systems,
backups can created with little effect on the Hyper-V host. These ShadowImage Replication software copies
can also be backed up to tape or disk. This means that child partitions hosted by Hyper-V can be recovered
very quickly.

Hyper-V Quick Migration

Hyper-V quick migration provides a solution for both planned and unplanned downtime. Planned downtime
allows for the quick movement of virtualized workloads to service the underlying physical hardware. This is the
most common scenario when considering the use of quick migration.
Quick migration requires the use of failover clustering because the storage must be shared between the
physical Hyper-V nodes. For a planned migration, quick migration saves the state of a running child partition
(memory of original server to the disk and shared storage), moves the storage connectivity from one physical
server to another and restores the partition to the second server (the disk and shared storage to memory on
the new server).
Consider the following when configuring disks for quick migration:
• Pass-through disks:
– Require that the virtual machine configuration file be stored on a separate LU from the LUs that host the
data files. Normally this is a VHD LU that is presented to the Hyper-V parent partition.
– Do not allow any other child partitions to share the virtual machine configuration file or VHD LU. Sharing
the virtual machine configuration file or VHD LU among child partitions can lead to corruption of data.
– For a child partition with a large number of LUs, the 26 drive letter limitation might become an issue. Pass-
through disks alleviate this. Pass-through disks do not require a drive letter because they are offline to the
parent.
• VHD disks:
– Best practice is to use one child partition per LU.
– Ability does exist to provision more than one child partition per LU, but remember all child partitions on the
VHD LU failover as a unit.
• Best practice is to leverage MPIO and Hitachi Dynamic Link Manager software for path availability and
improved I/O throughput within the Hyper-V cluster.

Hitachi Storage Cluster Solution

Integrating Hyper-V with Adaptable Modular Storage 2000 family replication solutions provides high availability
for disaster recovery scenarios. This solution leverages the Quick Migration feature of Hyper-V to allow for the
planned and unplanned recovery of child partitions under Hyper-V.
Disaster recovery solutions consist of remote LU replication between two sites, with automated failover of child
partition resources to the secondary site in the event that the main site goes down or is otherwise unavailable.
Data replication and control are handled by the Hitachi Storage Cluster (HSC) software and the storage system
controllers. This has little effect on the applications running in the child partition and is fully automated.
Consistency groups and time-stamped writes ensure database integrity.
Child partitions run as clusters resources within the Hyper-V cluster. If a node within the cluster that is hosting
the child partition fails, the child partition automatically fails over to an available node. The child partitions can
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