Managing Serviceguard Eighteenth Edition, September 2010

import and deport these disk groups. (For details on importing and deporting disk
groups, refer to the discussion of the import and deport options in the vxdg man page.)
The control script imports disk groups using the vxdg command with the -tfC options.
The -t option specifies that the disk is imported with the noautoimport flag, which
means that the disk will not be automatically re-imported at boot time. Since disk
groups included in the package control script are only imported by Serviceguard
packages, they should not be auto-imported.
The -foption allows the disk group to be imported even if one or more disks (a mirror,
for example) is not currently available. The -C option clears any existing host ID that
might be written on the disk from a prior activation by another node in the cluster. If
the disk had been in use on another node which has gone down with a TOC, then its
host ID may still be written on the disk, and this needs to be cleared so the new node’s
ID can be written to the disk. Note that the disk groups are not imported clearing the
host ID if the host ID is set and matches a node that is not in a failed state. This is to
prevent accidental importation of a disk group on multiple nodes which could result
in data corruption.
CAUTION: Although Serviceguard uses the -C option within the package control
script framework, this option should not normally be used from the command line.
Chapter 8: “Troubleshooting Your Cluster” (page 399), shows some situations where
you might need to use -C from the command line.
The following example shows the command with the same options that are used by
the control script:
# vxdg -tfC import dg_01
This command takes over ownership of all the disks in disk group dg_01, even though
the disk currently has a different host ID written on it. The command writes the current
node’s host ID on all disks in disk group dg_01 and sets the noautoimport flag for the
disks. This flag prevents a disk group from being automatically re-imported by a node
following a reboot. If a node in the cluster fails, the host ID is still written on each disk
in the disk group. However, if the node is part of a Serviceguard cluster then on reboot
the host ID will be cleared by the owning node from all disks which have the
noautoimport flag set, even if the disk group is not under Serviceguard control. This
allows all cluster nodes, which have access to the disk group, to be able to import the
disks as part of cluster operation.
The control script also uses the vxvol startall command to start up the logical
volumes in each disk group that is imported.
How Control Scripts Manage VxVM Disk Groups 319