HPP Enterprises P4000 SAN - Manual (Page 49)

49
thru changing this data to work with individual snapshots and at best works for only changing the
original volume’s UUID and persisting the old UUID with the snapshot. Best practice will suggest
limiting the use of the snapshots to the previously suggested use cases. Although no storage limitation
is implied with a snapshot as it is functionally equivalent to a read only volume, simplification is
suggested over implementing limitless possibilities.
Recall that a Storage Repository consists of a virtual machine’s virtual disk. In order to provide a
consistent application state, a VM needs to be shut down or initiated in order to create a snapshot
with the VSS provider. The storage volume will then be sure to have a known consistency point of
data from an application and operating system perspective and will be a good candidate for
initiating a storage-based snapshot, either locally to the same storage cluster or a remote snapshot. If
VSS is to be relied upon for a recovery state, upon recovery, creation of a VM from the source
XenCenter snapshot will be required as a recovery step.
The Storage Repository’s iSCSI volume will be selected as the source for the snapshot. In this
example, the VM XPSP2-05 is shut down. Highlight the XPSP2-05 volume in the CMC, right click and
select New Snapshot as shown in Figure 42. The Default Snapshot Name of XPSP2-05_SS_1 will be
pre-populated and by default, no servers will be assigned access. Note that if a New Remote
Snapshot is selected, a Management Group will need to be selected, new remote volume name
selected or created and a remote snapshot name created. It is possible to select creating a new
remote snapshot and selecting the local management group thereby making a remote snapshot a
local operation.
Figure 42. Select New Snapshot
SAN based Snapshot Rollback
A storage repository that has previously been Snapshot may be rolled back to that point in time,
thereby restoring the state of the virtual machine and virtual disk to its previous snapshot state. Once
a determination has been made that the current virtual machine and storage is no longer valid, the
storage repository upon which the virtual machine needs to recover must be reconnected to the
rollback volume, as shown in Figure 43.