HP 3PAR Cluster Extension Software Administrator Guide for Windows (5697-1821, April 2012)

and the number of remote Copy volume groups managed by HP 3PAR storage systems, the
online operation could time out. This can also happen if clx3PARrun is used in a script or
called by another program or 3PAR storage system IP cannot be reached.
• In the UCF.cfg file, if the ApplicationStartup attribute is set to RESYNCWAIT, HP 3PAR Cluster
Extension tries to resynchronize virtual volumes and waits until the Remote Copy volume group
is in a synced state. Depending on the amount of data to be transferred, it could take hours
to resynchronize. If this is the case, clx3PARrun may take some time to return. Do not stop
clx3PARrun, use the HP 3PAR Inform Management Console or HP 3PAR Inform CLI to check
the progress of syncing.
• Depending on the amount of data that is out of sync between the source and destination virtual
volumes while the Remote Copy link(s) is unavailable, a resynchronization or a complete copy
operation is initiated when the Remote Copy link(s) is re-established. The amount of delta data
to be transferred between the source and destination virtual volume could be large enough
for the copy process to take some time.
• To prevent the failover timeout trigger from terminating a failover command before it is finished,
the time to copy an average amount of daily processed (write) data should be measured and
the resource online timeout interval should be adjusted accordingly. Use only one (the slowest)
link used for Remote Copy to measure the copy time. This ensures that the average daily
generated data can be transferred fast enough from the remote HP 3PAR storage system, even
in the event of a single surviving replication link between the HP 3PAR storage systems. In
general, because the failover environment is dispersed into two (or more) data centers, the
failover time cannot be expected to be the same as it would be in a single data center with
a single shared disk device.
• After the RC link is brought down, remote copy takes more than 200 seconds to make the RC
volume group status to go to the stopped state. At this time, if failover is issued for the CLX
resource to the secondary side, CLX waits till the VG group goes to the stopped state or
"HP3PARRCPeriodicLinkDownTimeout" property value gets elapsed whichever is earlier.
Hence, the resource pending timeout value should be set to more than the
"HP3PARRCPeriodicLinkDownTimeout" property value.
• HP3PARCLICommandTimeout property value is used whenever HP 3PAR Cluster Extension
communicates with the HP 3PAR storage system. If the storage system is not responding within
the configured timeout value, the command will time out and return an error to the application.
Hence, this timeout value should be configured appropriately based on the time taken by the
3PAR CLI commands to execute and return the status. So the resource pending timeout value
should be set to more than the HP3PARCLICommandTimeout property value.
Restrictions for customized implementations
The following restrictions apply when using the HP 3PAR Cluster Extension CLI:
• The HP 3PAR Cluster Extension CLI command clx3parrun must be invoked before the
associated disk resources are activated on a server.
• Associated disk resources must not be activated on any other system. If other disk resources
are activated, HP 3PAR Cluster Extension may remove write-access rights for those disk devices
(putting them in read-only mode).
Pre-execution and post-execution programs
HP 3PAR Cluster Extension can invoke pre-execution and post-execution programs prior to or after
a HP 3PAR Cluster Extension failover/failback function. These programs can be any executable,
and must be able to provide return codes to HP 3PAR Cluster Extension. If the programs add
significant execution time to the application service startup process, the timeout values for the
startup process must be adjusted in the cluster software.
74 CLI commands and utilities