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

CAUTION:
Before switching the host to the offline state and performing operations on the VSM elements (virtual
disks, VDGs, and snapshots) that belong to the host, shut down the host or disconnect the host from
the SAN. If you do not shut down or disconnect the host, the host may attempt to write to the virtual
disk at the same time that VSM makes changes to the virtual disk structure (deletes a PiT, deallocates
a temporary virtual disk, and so on), which may cause data corruption. Also, by dismounting the
device, the device caches are flushed such that all pending work is sent to the media. Failure to
dismount the device may lead to loss of data.
You can perform the following operations when the host is offline:
• Delete a virtual disk owned by the host.
• Remove permission from a virtual disk.
• Add a virtual disk to a virtual disk group. Before doing this, the virtual disk must have the same
set of presentations as the virtual disk group or no presentations.
• Change the name of a virtual disk. This can only be done when a host is offline.
• The following are snapshot service operations:
• Create a PiT on a virtual disk owned by the host.
• Delete a snapshot of a PiT of a virtual disk owned by the host.
• Delete a PiT of a virtual disk owned by the host.
• Roll back a virtual disk or virtual disk group.
• Restore a snapshot.
• Remove permission from a snapshot or a virtual disk with PiT.
• Create a snapclone group.
• Create an asynchronous mirror group.
• Create a migration group.
For information about snapshots, see “Using snapshots” on page 193. For information about snapclones,
see “Using snapclones” on page 233. For information about migrations, see
“Using migration” on page 249. For information about mirroring, see “Using mirroring” on page 259.
To move a host into the offline state:
1. Right-click the host.
2. Select Manage On/Offline State > Set Host Offline. A confirmation screen appears.
3. Click Finish. The host is now offline.
To move a host from the offline to the online state:
1. Right-click the host.
2. Select Manage On/Offline State > Set Host Online. A confirmation screen appears.
3. Click Finish. The host is now online and presentations are restored to the host.
Deleting hosts
When a host is physically removed from the SAN, VSM detects the removal and changes the host’s
status to absent. VSM enables you to delete hosts if they are absent. You would normally do this if
Working with hosts156