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vx_emerg_start - start Veritas Volume Manager from recovery media
vx_emerg_start [-m] [-r root_daname] hostname
The vx_emerg_start utility can be used to start Veritas Volume Manager (VxVM) when a system is booted from alternate media, or when a system has been booted into Maintenance Mode Boot (MMB) mode. This allows a rootable VxVM configuration to be repaired in the event of a catastrophic failure.
vx_emerg_start verifies that the /etc/vx/volboot file exists, and checks the command-line arguments against the contents of this file.
Mounts the root file system contained on the rootvol volume after VxVM has been started. Prior to being mounted, the rootvol volume is started and fsck is run on the root file system.
Specifies the disk access name of one of the members of the root disk group that is to be imported. This option can be used to specify the appropriate root disk group when multiple generations of the same root disk group exist on the system under repair. If this option is not specified, the desired root disk group may not be imported if multiple disk groups with the same name exist on the system, and if one of these disk groups has a more recent timestamp.
Specifies the system name (nodename) of the host system being repaired. This name is used to allow the desired root disk group to be imported. It must match the name of the system being repaired, as it is unlikely to be recorded on the recovery media from which you booted the system.
HP-UX Maintenance Mode Boot (MMB) is intended for recovery from catastrophic failures that have prevented the target machine from booting. If a VxVM root volume is mirrored, only one mirror is active when the system is in MMB mode. Any writes that are made to the root file system in this mode can corrupt this file system when both mirrors are subsequently configured.
The vx_emerg_start script allows VxVM to be started while a system is in MMB mode, and marks the non-boot mirror plexes as stale. This prevents corruption of the root volume or file system by forcing a subsequent recovery from the boot mirror to the non-boot mirrors to take place.
After VxVM has been started, various recovery options can be performed depending on the nature of the problem. It is recommended that you use the vxprint command to determine the state of the configuration.
One common problem is when all the plexes of the root disk are stale as shown in the following sample output from vxprint:
v rootvol root DISABLED 393216 - ACTIVE -
pl rootvol-01 rootvol DISABLED 393216 - STALE -
sd rootdisk01-02 rootvol-01 ENABLED 393216 0 - -
pl rootvol-02 rootvol DISABLED 393216 - STALE -
pl rootvol-02 rootvol DISABLED 393216 - STALE -
sd rootdisk02-02 rootvol-02 ENABLED 393216 0 - -
In this case, the volume can usually be repaired by using the vxvol command as shown here:
vxvol -g 4.1ROOT -f start rootvol
If the volume is mirrored, it is put in read-write-back recovery mode. As the command is run in the foreground, it does not exit until the recovery is complete. It is then recommended that you run fsck on the root file system, and mount it, before attempting to reboot the system:
fsck -F vxfs -o full /dev/vx/rdsk/4.1ROOT/rootvol
mount -F vxfs /dev/vx/dsk/4.1ROOT/rootvol /tmp_mnt
fsck(1M), mkdir(1M), mount(1M), vxintro(1M), vxprint(1M), vxvol(1M)