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ME4 Series snapshots with Hyper-V
25 Dell EMC PowerVault ME4 Series and Microsoft Hyper-V | 3921-BP-WS
4 ME4 Series snapshots with Hyper-V
ME4 Series snapshots can be used to protect Hyper-V workloads. They are space-efficient snapshots,
meaning they consume no additional space unless they are mapped to a host and new data is written. For
general use cases and best practices regarding snapshots, see the ME4 Series Administrator’s Guide.
ME4 Series snapshots allow administrators to do the following in Hyper-V environments:
• Provision an isolated test environment that matches the production environment
• Provision new servers from a snapshot that is designated as a gold image source
ME4 Series snapshots can be taken of volumes mapped as LUNs to a Hyper-V environment regardless of
content. This applies to data volumes, cluster shared volumes (CSV), pass-through disks, and in-guest iSCSI
volumes. These volumes can also be replicated to another ME4 Series array for DR or other purposes.
4.1 Crash-consistent and application-consistent snapshots
Unless a server is powered off at the time a snapshot is taken, or first put into a consistent state (for example,
by leveraging the Microsoft volume shadow copy service (VSS) to gracefully pause a server or application),
ME4 Series snapshots are considered crash-consistent. When recovering a server using a crash-consistent
snapshot, it is like having the server recover from a power outage at that point in time. In most cases, servers
and applications are resilient enough to recover to a crash-consistent state without any complications,
whether the cause is an unexpected power outage, or the server is being recovered to a previous point in
time to recover from an event such as a malware infection. An exception to this is when the Hyper-V
environment hosts a transactional workload such as Microsoft Exchange or SQL Server. With transactional
workloads, the risk of data loss or corruption is higher when attempting to recover to a crash-consistent state.
Some examples for how to configure and use Dell EMC ME4 snapshots for a Hyper-V environment are
provided in the following sections.
4.2 Guest VM recovery with ME4 Series snapshots
Hyper-V guest VMs can be recovered to a previous point in time by using crash-consistent snapshots.
Snapshots can be used to create copies of VMs in an isolated environment at the same or a different location
when replication between ME4 Series arrays is used. This section provides guidance and best practices for
several different recovery options using snapshots.
4.2.1 Recover a guest VM on a standalone Hyper-V host
In this scenario, the virtual hard disk and configuration files for a VM reside on a data volume that is mapped
to a Hyper-V host.
Option 1: Recover the existing data volume on the host that contains the VM configuration and virtual hard
disks by using an ME4 Series snapshot rollback.
• This may only be practical if the data volume contains only one VM. If the data volume contains
multiple VMs, it will still work if all the VMs are being recovered to the same point in time. Otherwise,
option 2 or 3 would be necessary if needing to recover just one VM.
• This will allow the VM being recovered to power up without any additional configuration or recovery
steps required.
• It is essential to document the LUN number, disk letter, or mount-point information for the volume to
be recovered, before starting the recovery.