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

Detaching plexes
To temporarily detach one data plex in a mirrored volume, use the following
command:
# vxplex [-g diskgroup] det plex
For example, to temporarily detach a plex named vol01-02 in the disk group,
mydg, and place it in maintenance mode, use the following command:
# vxplex -g mydg det vol01-02
This command temporarily detaches the plex, but maintains the association
between the plex and its volume. However, the plex is not used for I/O. A plex
detached with the preceding command is recovered at system reboot. The plex
state is set to STALE, so that if a vxvol start command is run on the appropriate
volume (for example, on system reboot), the contents of the plex is recovered and
made ACTIVE.
When the plex is ready to return as an active part of its volume, it can be reattached
to the volume.
See “Reattaching plexes” on page 268.
Automatic plex reattachment
When a mirror plex encounters irrecoverable errors, Veritas Volume Manager
(VxVM) detaches the plex from the mirrored volume. By default, VxVM
automatically reattaches the affected mirror plexes when the underlying failed
disk or LUN becomes visible. When VxVM detects that the device is online, the
VxVM volume components on the involved LUN are automatically recovered, and
the mirrors become usable.
VxVM uses the DMP failed LUN probing to detect when the device has come online.
The timing for a reattach depends on the dmp_restore_interval, which is a
tunable parameter. The number of LUNs that have reconnected may also affect
the time required before the plex is reattached.
VxVM does not automatically reattach plexes on site-consistent volumes.
When VxVM is installed or the system reboots, VxVM starts the vxattachd
daemon. The vxattachd daemon handles automatic reattachment for both plexes
and sites. Thevxattachd daemon also initiates the resynchronization process for
a plex. After a plex is successfully reattached, vxattachd notifies root.
267Creating and administering plexes
Detaching plexes