Setup Guide

70 Best Practices
Shut Down VMs Before a Snapshot
In scenarios where application consistency cannot be achieved using
frameworks such as Microsoft
®
VSS or VDS, etc., creating a snapshot or clone
of an SR when VMs are powered down ensures a volume that can be cleanly
recovered. Scenarios where all virtual disks of a VM are virtualized through
the XenServer Domain fall into this category. Though this approach
guarantees file system 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, the virtual machines are suspended and the suspended state
is saved in the Suspend Storage Repository. After suspending the VMs on the
SR, a snapshot of the SR on which the VM virtual disks reside and the
Suspend SR (if different from the SR on which VM virtual disks reside) can
be taken to ensure file system and application consistent snapshots. When
VMs are booted from the suspended state, the VMs resume at the point
where they were suspended. Depending on the memory state of the VMs on
the SR, the service downtime can be less or more. 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
Suspend all the VMs on the SR. This requires XenTools to be installed and
running in all VMs.
2 From the primary XenServer host, backup the VM metadata for the VMs
on the SR.