Identifying the source and target volumes – HP StorageWorks XP Remote Web Console Software User Manual
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Structure for AIX host servers:
When you use XP Business Copy on the AIX host servers, HP technical support strongly
recommends that you use two AIX host servers to locate P-VOLs in one host server, and the
paired S-VOLs in the other. If you use only one AIX host server, consider the following:
◦
When the paircreate or pairresync operation is performed, XP Business Copy copying
takes place between the P-VOL and S-VOL. Consequently the P-VOL and S-VOL have the
same PVID.
◦
If the host server reboots while the P-VOL and S-VOL have the same PVID, the host server
might misidentify the P-VOL and S-VOL (that is, identify the S-VOL as the P-VOL) after
rebooting.
◦
You can use the recreatevg command to change the PVID of the P-VOL and S-VOL.
However, until the recreatevg command is executed, the PVID remains the same, and the
host server might misidentify the volumes.
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When you resynchronize a pair by Quick Restore:
During a quick restore operation, the RAID levels, HDD types, and Cache Residency Manager
settings of the P-VOL and S-VOL are exchanged. For example, if the P-VOL has a RAID-1 level
and the S-VOL has a RAID-5 level, the quick restore operation changes the RAID level of the
P-VOL to RAID-5 and of the S-VOL to RAID-1. This also applies to RAID-6 volumes. To avoid
any performance impact due to the quick restore operation, perform the following:
◦
Make sure that the P-VOL and S-VOL have the same RAID level and HDD type before
performing the quick restore operation. To restore the original RAID levels after quick
restore, stop host I/Os to the pair, split the pair, perform the quick restore operation for
that pair again, and then restart the host I/Os to the pair.
◦
Because the Cache Residency Manager settings are exchanged during a quick restore
operation, you must perform the two following operations:
–
Set the same Cache Residency Manager settings (locations) for the P-VOL and S-VOL
before performing the quick restore operation.
–
Release the Cache Residency Manager settings of the P-VOL and S-VOL before the
quick restore operation, and then reset the Cache Residency Manager settings of
the P-VOL and S-VOL after the pair changes to PAIR status as a result of the quick
restore operation.
If you omit any of the operations listed above, the cache residence location change may
cause I/O performance to diminish.
For details about Cache Residency Manager settings, see the HP XP24000/XP20000
Cache Residency Manager User Guide.
Identifying the Source and Target Volumes
For each volume, set the LU path, whether the volume will be a P-VOL or an S-VOL, and the other
volumes in its pair (see
for a sample table). For details about how to set the
LU path, see the HP XP24000/XP20000 LUN Manager User Guide.
Assessing Requirements
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