Recovery from failures using resynchronization, Required conditions – HP XP Racks User Manual
Page 62
3.
On the primary storage system, delete the quorum disk ID.
4.
On the secondary storage system, register the ESAM primary storage system to the secondary
storage system.
5.
On the secondary storage system, create a Continuous Access Synchronous pair. The data
flow is from secondary to primary sites.
6.
Format the quorum disk.
7.
Continue by changing the Continuous Access Synchronous pair to a ESAM pair (below) or
recreating the ESAM pair (next steps).
If changing the Continuous Access Synchronous pair to a ESAM pair, continue with this step.
If using RWC, go directly to the RWC step, below.
1.
When the Continuous Access Synchronous pair creation operation is completed, run the
horctakeover
RAID Manager command on the primary storage system S-VOL. This
reverses the P-VOL/S-VOL relationship; the S-VOL on the primary storage system now
becomes the P-VOL.
2.
On the primary and secondary storage systems, add the quorum disk.
3.
Using RWC, on the primary system, split the Continuous Access Synchronous pair.
4.
Using RWC, on the primary system, change the Continuous Access Synchronous pair to
a ESAM pair. See
“Changing Continuous Access Synchronous pairs to ESAM pairs ”
for details.
8.
If recreating the ESAM pair using RAID Manager:
1.
When the copy operation in Step 5 completes, release the Continuous Access Synchronous
pair.
2.
On the primary and secondary storage systems, add the quorum disk.
3.
On the primary storage system, run the paircreate command to create the ESAM pair.
9.
If recreating the ESAM pair using RWC:
1.
Make sure the Continuous Access Synchronous pair creation operation completed, then
release the Continuous Access Synchronous pair.
2.
On the primary and secondary storage systems, add the quorum disk.
3.
On the primary storage system, create the ESAM pair.
10. On both primary and secondary storage systems, in RWC make sure that Type shows ESAM.
11. Using multipath software, vary the owner and non-owner paths online.
12. Restart host I/O.
Recovery from failures using resynchronization
In some cases, you can resynchronize an ESAM pair to recover a volume pair, quorum disk, or a
volume pair and quorum disk from failure. The recovery process can only be used if certain
conditions exist.
Required conditions
You can only use this method if all of the following conditions exist:
•
The ESAM volumes are not blocked.
•
If there was a quorum disk failure, the disk does not need to be replaced.
•
Data was not lost as a results of shared memory initialization caused by a power outage.
Determining which resynchronization recovery procedure to use
Determining which recovery procedure to use involves analyzing the information in the system
information messages (SIM) and path failure system messages to determine if all of the conditions
required to use resynchronization exist, then selecting the procedure to use.
62
Disaster recovery