HP StorageWorks SAN Virtualization Services Platform administrator guide (5697-8056, March 2009)

the mirror and fails because it cannot access one of the tasks. You must direct the mirror on how
to recover. The synchronous mirror group status is Partial.
• If the passive DPM and the active VSM are not on the same site, the failover request fails, and the
host I/O operations fail. Manual intervention for recovery is expected.
Synchronous mirror failure analysis
1. Find out the actual status of the sites by checking the status of the individual components locally
on each site.
2. If the individual components are online, but the active VSM does not see those of the other site,
then the sites are probably just disconnected. Verify this is the case.
Recovering synchronous mirror volumes from site disconnection
1. Recover the inter-switch link connection between the sites, if possible. Then, initiate a resynchron-
ization (right-click the group, and select Resume) for the synchronous mirror groups after the
restoring the inter-switch link connection.
2. If you cannot recover the connection between sites within a reasonable time, consider appointing
one of the sites as the surviving site and apply the recovery procedure for site failure. Work ac-
cording to Recovering synchronous mirror groups on the surviving site below.
CAUTION:
Do not attempt to partially restore some applications on each site, because it will not be possible to
rejoin the sites back into a stretched domain.
Recovering synchronous mirror groups on the surviving site
If one of the sites is down and cannot be recovered within a reasonable amount of time, you can use
the synchronous mirror task on the surviving site to recover from the site failure. You can recover by
using these procedures:
• Force Resume (see “Recovering the surviving site by using Force Resume” on page 83)
• Force Delete (see “Recovering the surviving site by using Force Delete” on page 86)
NOTE:
• Whenever possible, use Force Resume before using Force Delete. Force Resume maintains the
synchronous mirror group structure and allows the option to resume mirroring with the failed site
after the site is recovered. A Force Delete operation deletes the synchronous mirror structure and
forces you to recreate the synchronous mirror group and the synchronous mirror group jobs.
• Single component failures can usually be recovered by using the standard management operations
of synchronous mirroring (resynchronization, resume, change operation mode, break, or delete).
Only use Force Resume and Force Delete as a last resort for multiple failures, site failures, and
extended intersite link outages.
Recovering the surviving site by using Force Resume
1. If possible, on the site that is down, turn off the power to all of the DPMs that are involved in
synchronous mirroring and the VSM server.
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