HP StorageWorks SAN Virtualization Services Platform Manager user guide (AG781-96017, March 2009)

Using snapshots with synchronous mirrors
You can create a snapshot PiT on a synchronous mirror group or on the destination virtual disk of a
synchronous mirror task. When you create a PiT on a group, a PiT is created on the virtual disk of
each task. When you create a snapshot PiT on a virtual disk, the PiT is created only on that virtual
disk.
To create a PiT:
1. Select the entity on which to create the PiT.
• To create a PiT on the destination virtual disk, right-click the virtual disk, rather than the task,
on which to create a user PiT. The Create User PiT screen appears.
• To create a PiT on the group, select Manage> Create User PiT. The Create User PiT screen
appears.
2. In the PiT name field, enter a name for the PiT. This is the PiT name only on the source domain
of the group. When a user PiT is copied to task destinations, the mirror service automatically
generates a new name for the PiT. The new name is a combination of the destination virtual disk
name, the letters “UP” to indicate a user PiT, and a unique time stamp number assigned to the
PiT when it was created by the source domain.
3. In the Comment field, enter any text you want.
4. Click Next. A confirmation screen appears.
5. Click Finish. The PiT is created, and the group’s tasks start copying the PiT to their destinations.
The PiT appears in the Source Domain’s PiTs tab for the group. You can track the life cycle of
the PiT in the Source & Destination PiTs tab. For more information, see “Async mirror group
information—Source & Destination PiTs tab” on page 266.
Mirroring cluster virtual disks
The mirror service supports synchronous mirroring on virtual disks that are used as cluster resources.
To mirror a virtual disk used as a cluster resource, define the virtual disk as a cluster resource and
configure it in a cluster application before inserting the virtual disk into a sync mirror group. See
“Defining virtual disks as clustered” on page 121 for instructions on how to define a cluster resource
and configure it in a cluster application.
When a cluster of nodes has permission to use a synchronous mirror group, the node that is reserving
the group is indicated by the Reserved field in the Host Presentation tab for the group. Each node
reports the group’s status, and the reported status appears as Mirror Status in the Host Presentation
tab for the group. Note that when a synchronous mirror group is a cluster resource, the implications
of the group’s status are slightly different from a regular sync mirror group.
When mirroring a cluster resource, each virtual disk used by the cluster application is a separate VSM
virtual disk. Therefore:
• Insert each such virtual disk into a separate sync mirror group.
• When recovering from cluster failure, handle the Quorum disk group before the other group(s)
used by the cluster application. If the Quorum group status is Absent or Partial, the Quorum group
is the only group for which the statuses are updated.
• The mirror states of all other cluster objects update only when the Quorum group returns to Normal,
Snap-sync, or Journal status.
See “Troubleshooting cluster virtual disks” on page 299 for a description of each task status and group
status for sync mirror groups used by cluster nodes, and suggested actions you can take when the
status indicates a problem.
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