HP StorageWorks SAN Virtualization Services Platform 2.1 release notes (5697-8060, March 2009)

5. Halt the first I/O stream to the virtual disk (initiated in step 3 above).
6. Unpresent the virtual disk to its host (presented in step 2 above).
7. Delete the virtual disk (created in step 1 above).
Carrying this example further, if you decide to delete the pool from which virtual disks are created,
you must delete all the virtual disks in that pool. This requires that you delete or halt all operations
being performed on or by those virtual disks, like I/O, snapshots, PiTs, presentations, and so on.
• HP recommends that you limit the number of virtual disks in a pool to 500, with a maximum limit
of 1000. In addition, avoid creating virtual disks that span more than one pool.
• Do not remove a single snapshot from a virtual disk group snapshot set.
• When a threshold limit is reached, a single event log message is generated, instead of a message
being sent every five minutes.
• Restoring a VSM setup from a backup can be safely performed only if there are no PiTs in the
system. If PiTs exist (either created directly or by Business Copy or Continuous Access applications),
their metadata in the setup backup may be invalid and may result in data loss/corruption if restored.
• Do not change any back-end logical unit characteristic (for example, number, name, size [by ex-
panding or contracting], and so on) once it has been virtualized (for example, entered into a VSM
storage pool) or is being managed by the VSM. The LUN identification has been written on the
LU by VSM.
• Before starting a migration task, make sure the task does not have any PiTs (such as user PiTs or
mirror PiTs). If PiTs exist, they must be deleted before the task starts, otherwise a future snapshot
created on these PiTs (or a rollback to them) after migration will not be consistent.
• Before installing or uninstalling VSM, you must make sure that all iSCSI connections are disconnec-
ted. You must log out of all existing iSCSI connections. See the HP StorageWorks SAN Virtualization
Services administrator guide for the upgrade procedure.
• After a disruption (perturbation) of VSM connections, wait at least 15 minutes to let the VSM redis-
cover all paths.
• When booting from the SAN, make sure the host only sees that LUN through one path when there
is no multipathing software on the host.
• When rebooting one DPM, wait at least 30 minutes before rebooting the other DPM.
• Before disconnecting a VSM server from the domain, ensure that the other VSM server is running.
There is an increased risk of a Windows fault when disconnecting (even partially) a VSM server
from the domain (for example, to perform maintenance). The lack of an operational second VSM
server can lead to I/O failure.
• When ordering Continuous Access SVSP LTU licenses, you receive an equivalent amount of Business
Copy SVSP LTU licenses. These additional Business Copy licenses are required by the current
replication software and should not be used for local Business Copy processes.
Issues and workarounds
This section describes known issues for the SVSP operating systems, Virtualization Service Manager
(VSM), Data Path Module (DPM), and VSM command line interface (CLI) applications. Workarounds
are provided when possible.
Operating system issues
Synchronous mirrors on Windows Server 2008
Microsoft hotfix 957522 is required when running synchronous mirrors on Windows Server 2008.
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