HP Veritas Volume Manager 5.0 -UX 11i v3 manual Recovery from a loss of site connectivity

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Administering sites and remote mirrors

Failure scenarios and recovery procedures

Failure scenario Recovery technique

Failure of storage at a site.

See “Recovery from storage failure” on page 442.

Failure of both hosts and storage at a site. See “Recovery from site failure” on page 443.

Recovery from a loss of site connectivity

If the network links between the sites are disrupted, the application environments may continue to run in parallel, and this may lead to inconsistencies between the disk group configuration copies at the sites. When connectivity between the sites is restored, a serial split-brain condition may then exist between the sites. One site must be chosen as having the preferred version of the disk group configuration copies. The configuration copies at the other sites can then be updated from these copies.

You can use the following commands to reattach a site and recover the disk group:

#vxdg -g diskgroup -o overridessb reattachsite sitename

#vxrecover -g diskgroup

In the case that the host systems are configured at a single site with only storage at the remote sites, the usual resynchronization mechanism of VxVM is used to recover the remote plexes when the storage comes back on line.

Recovery from host failure

If one or more cluster nodes fail at a site, but the storage remains online, this is handled either by VCS failover in the case of the Storage Foundation HA product, or by node takeover in the case that the node was the master for a shared disk group as supported by the Storage Foundation Cluster File System software.

Recovery from storage failure

If storage fails at a site, the plexes that are configured on that storage are detached locally if a site-consistent volume still has other mirrors available at the site. The hot-relocation feature of VxVM will attempt to recreate the failed plexes on other available storage in the disk group. If no plexes of a site-consistent volume remain in operation at a site, and hot-relocation cannot recreate the plexes at that site, the site is detached. Because site connectivity has not been lost, applications running on hosts at the site can still access data