Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

Recovering 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 at the other sites.
When the storage comes back online, the vxattachd reattaches the site
automatically.
See “Automatic site reattachment” on page 503.
If the vxattachd is not running, use the following commands to reattach a site
and recover the disk group:
# vxdg -g diskgroup reattachsite sitename
# vxrecover -g diskgroup
Recovering from site failure
If all the hosts and storage fail at a site, use the following commands to reattach
the site after it comes back online, and to recover the disk group:
# vxdg -g diskgroup [-o overridessb] reattachsite sitename
# vxrecover -g diskgroup
The -o overridessb option is only required if a serial split-brain condition is
indicated. A serial split-brain condition may happen if the site was brought back
up while the private network link was inoperative. This option updates the
configuration database on the reattached site with the consistent copies at the
other sites.
Automatic site reattachment
The automatic site reattachment daemon, vxattachd, provides automatic
reattachment of sites. The vxattachd daemon uses the vxnotify mechanism to
monitor storage coming back online on a site after a previous failure, and to restore
redundancy of mirrors across sites.
If the hot-relocation daemon, vxrelocd, is running, vxattachd attempts to reattach
the site, and allows vxrelocd to try to use the available disks in the disk group to
relocate the failed subdisks. If vxrelocd succeeds in relocating the failed subdisks,
it starts the recovery of the plexes at the site. When all the plexes have been
503Administering sites and remote mirrors
Failure scenarios and recovery procedures