Metrocluster with Continuous Access XP Version A.11.00 Release Notes, August 2010 (B8109-90027)

Some delay in package startup time occur in those situations where resynchronization
of data from one side to another is required. For example, if the Metrocluster package
fails over to SVOL side and if there is a Continuous Access link failure, it performs
SVOL takeover(SSWS). After Continuous Access link recovery, if the Metrocluster
package fails back to PVOL side, it resynchronizes the data from the SVOL side to the
PVOL side.
For Continuous Access Journal mode package, journal volumes in PVOL may contain
a significant amount of journal data to be transferred to SVOL, the package startup
time may increase significantly when the package fails over and waits for all of the
journal data to be flushed.
The value of RUN_SCRIPT_TIMEOUT in the package ASCII file should be set to
NO_TIMEOUT or to a large value. This value should be enough to take into consideration
the extra startup time that is attributed to getting the status from the XP series disk
array. When using asynchronous data replication, the value has to be 360 seconds or
more.
Additional Notes on Disks, Logical Volumes, and Filesystems
The following are guidelines relating to the management of disks, LVM or VxVM/CVM
storage groups, logical volumes, and filesystems in Metrocluster with Continuous
Access XP packages:
• No checking of the status of the host ports is done. It is assumed that at least one
storage link is functional, otherwise the storage group activation will fail.
• A given file system must not reside on more than one XP frame for either the PVOL
or the SVOL.
• A given storage group (LVM volume group or VxVM disk group) must not span
across more than one XP frame for either the PVOL or the SVOL.
• Each host must be connected to only the XP series disk arrays that contain either
the PVOL or the SVOL. A given host must not be connected to both the PVOL and
the SVOL of a Continuous Access pair except when using Remote Command
Device configured over extended SAN.
• When using the paircreate command to create PVOL/SVOL Continuous Access
pairs, specify the -c 15 switch to ensure the fastest resynchronization in order
to reduce vulnerability to a rolling disaster.
• When using the pairresync command to resynchronize PVOL/SVOL Continuous
Access pairs, specify the -c 15 switch to ensure the fastest resynchronization in
order to reduce vulnerability to a rolling disaster.
• HP recommends you to use the VxVM/LVM volume monitor for effective and
persistent monitoring of VxVM or LVM storage. For more information, see Chapter
1, Designing a Metrocluster in Designing Disaster Recovery HA Clusters using
Metrocluster and Continentalclusters, September 2010 available at http://www.hp.com/
go/hpux-serviceguard-docs —> HP Metrocluster.
Additional Notes on Disks, Logical Volumes, and Filesystems 9