3PAR InForm OS 2.3.1 MU4 Release Notes (QL226-96261, September 2011)

• 256 Read/Write Snapshots - In InForm OS 2.3.1 and 2.3.1 MU2, the number of read/write
snapshots was increased to 256 per virtual volume. Previous release supported a smaller maximum
number of read/write snapshots per virtual volume. A downgrade will be prevented if any virtual
volume has more read/write snapshots than the maximum supported on the previous release.
When enough snapshots have been removed to meet this criterion the downgrade is allowed.
• Multiple Read/Write Snapshots per Read-Only Snapshot - In InForm OS 2.3.1 and 2.3.1 MU2,
the creation of multiple read/write snapshots per read-only snapshot is permitted. Previous releases
supported a single read/write snapshot per read-only snapshot. A downgrade will be prevented
if any read-only snapshot has more than one read/write snapshot. Once enough read/write
snapshots have been removed to meet this criteria, the downgrade is allowed.
• Synchronous Long Distance Remote Copy - If there are Remote Copy groups configured with
multiple targets, those groups must be removed or reduced to a single target before a downgrade
is allowed.
• 16 TB Support - Virtual volumes larger than the maximum size supported in a previous release
must be removed before a downgrade is allowed.
• Multiple Remote Copy Links per Node - InForm OS release 2.3.1 and 2.3.1 MU2 allow multiple
Remote Copy links to be configured on a individual node. Previous releases only allowed a single
link per node. Before downgrading, ensure that additional Remote Copy links are dismissed to
ensure a valid configuration for the downgrade. A check is run prior to downgrade to validate
the existing Remote Copy link configuration.
Issues Causing a Change to the InForm Configuration
The following issue causes a change to the InForm OS configuration when downgrading from InForm
OS release 2.3.1 or 2.3.1 MU2.
• Host Personas - If a system running InForm OS release 2.3.1 MU2 is downgraded, host persona
fields are cleared and the old port persona settings resume effect. However, these settings are
not kept up-to-date nor are they converted back on downgrade, so they will not reflect any
configuration changes made since loading 2.3.1 MU2. On a system which only ran 2.3.1 MU2,
there will be no port persona settings to revert to.
Prior to the downgrade, a check is run to ensure the system can run in the downgraded state. If
host persona specific configurations are detected, a message is issued. This condition will need
to be resolved before the downgrade is permitted. One example of this would be different host
persona settings sharing a port which can not be supported via port personas.
Remote Copy and Recovery Manager Snapshot Interaction Issues
When a non-zero scheduled synchronization period is specified for an Asynchronous Periodic Remote
Copy volume group, any application coordinated snapshots taken on the same Remote Copy group
by Recovery Manager may conflict with the periodic snapshots taken by Remote Copy. This can result
in Remote Copy (RC) snapshots that cannot be deleted and/or are not coordinated with the application.
Workaround
Remote Copy can support the mixture of Recovery Manager snapshots and Remote Copy snapshots
(outside of Recovery Manager) if the following procedure is followed:
Inside the Recovery Manager Windows scheduler script:
1. Set the Remote Copy period to 0.
2. Verify Remote Copy SyncStatus as "Synced".
3. Execute Recovery Manager snapshot creation for Remote Copy.
4. Wait for SyncStatus to be completed and Recovery Manager to take a snapshot of secondary
volumes.
5. Recovery Manger will monitor the SyncStatus to be "Synced" every 120 seconds as default then
issue snapshot creation of secondary volumes. Wait until these snapshots complete.
10 HP 3PAR InForm Operating System Release Notes