Setup Guide
52 Best Practices
Shut Down VMs Before a Snapshot
In scenarios where you cannot achieve application consistency using
frameworks such as Microsoft
VSS or VDS, etc., you can create a snapshot or
clone of an SR when VMs are powered down and ensure a volume recovery
that is clean. Scenarios where all virtual disks of a VM are virtualized through
the XenServer domain fall into this category. Though this approach
guarantees file system-consistent and application-consistent volume recovery,
there is service downtime as VMs on the SR need to be shut down before a
snapshot operation. This approach is useful when there are multiple VMs on
an SR. Follow the steps below to take a snapshot in such a scenario:
1
Shut down all the VMs on the SR.
2
From the primary XenServer host, backup the VM metadata for the VMs
on the SR.
3
Take a snapshot of the SR.
4
Start up the VMs on the primary XenServer host.
5
Attach the snapshot of the SR on the secondary XenServer host.
6
On the secondary XenServer host, restore the VM metadata to recover
VMs.
7
Turn on the VMs on the secondary XenServer host.
Suspend VMs Before a Snapshot
In this scenario you suspend the VMs and the suspended state is saved in the
Suspend Storage Repository. After you suspend the VMs on the SR, you can
take a snapshot of the Suspend SR and the SR on which the VM virtual disks
reside. This ensures file system and application consistent snapshots. When
you boot the VMs from the suspended state, the VMs resume at the point
where they were suspended.
The service downtime depends on the memory state of the VMs on the SR.
This approach is useful when there are multiple VMs on an SR. To take a
snapshot in such a scenario:
1
Suspend all the VMs on the SR. You must install XenTools and run them
in all VMs.
2
From the primary XenServer host, backup the VM metadata for the VMs
on the SR.