vx_emerg_start(1M) VxVM 3.5 vx_emerg_start(1M)
1 Jun 2002
NAME [Toc] [Back]
vx_emerg_start - start VERITAS Volume Manager from recovery media
SYNOPSIS [Toc] [Back]
vx_emerg_start [-f] [-m] [-r root_daname] hostname
DESCRIPTION [Toc] [Back]
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 Emergency Mode Boot 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.
If the system is booted in Maintenance Mode Boot (MMB) mode and the
volboot file needs to be updated, vx_emerg_start outputs diagnostic
messages before aborting without updating the volboot file. The -f
option can be used to force the command to update the volboot file
(see OPTIONS below).
OPTIONS [Toc] [Back]
-f If the system is in Maintenance Mode Boot (MMB) mode, this option
forces vx_emerg_start to update the contents of the
/etc/vx/volboot file.
Note: The vx_emerg_start command should initially be invoked
without specifying the -f option.
See NOTES below for the possible consequences of updating the
volboot file when the system is in MMB mode.
-m 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.
-r root_daname
Specifies the disk access name of one of the members of the
desired rootdg disk group. This option can be used to specify the
appropriate rootdg when multiple generations of the rootdg disk
group exist on the system under repair. If this option is not
specified, the default behavior is to pick the rootdg with the
most recent timestamp.
ARGUMENTS [Toc] [Back]
hostname
Specifies the system name (nodename) of the host system being
repaired. This name is used to allow importation of the desired
rootdg. 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.
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vx_emerg_start(1M) VxVM 3.5 vx_emerg_start(1M)
1 Jun 2002
NOTES [Toc] [Back]
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. The script avoids writing to the root file system unless
it is necessary to update the volboot file. In this case,
vx_emerg_start warns you that modification of volboot is required
before aborting. You must reinvoke vx_emerg_start with the -f option
to force vx_emerg_start to update the volboot file.
After running vx_emerg_start with the -f option to start VxVM in MMB
mode on a mirrored root, it is recommended that you remove the root
mirror from which the system was not booted. This can be done as
follows:
1. Determine which disk you booted from.
2. Run the command vxdisk list, and locate your system's boot disk
in the leftmost DEVICE column of the output. Find the disk media
(DM) name of the boot device by locating the boot device in the
DISK column. This will be a name such as rootdisk01 or
rootdisk02. Also note the disk media name of the mirror disk.
3. Run the command vxprint -g rootdg rootvol. If your system has a
mirrored root volume, two plex entry lines are listed (with pl in
the leftmost column), and immediately below each plex entry is
the subdisk entry that is associated with the plex (with sd in
the leftmost column).
4. Examine the NAME field that is immediately to the right of the sd
entry. This is the subdisk name, which is composed of the DM
name followed by -nn, where nn is a number, such as 03 or 04,
that uniquely identifies the subdisk. Identify the DM name of
the root mirror disk from which the system was not booted.
5. Use the following command to remove the plex and its associated
subdisk for the root mirror disk from which the system was not
booted:
vxplex -o rm dis plex
The following example shows how to remove the rootvol plex that is
associated with the disk rootdisk02:
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vx_emerg_start(1M) VxVM 3.5 vx_emerg_start(1M)
1 Jun 2002
# vxprint -g rootdg rootvol
TY NAME ASSOC KSTATE LENGTH PLOFFS STATE
v rootvol root ENABLED 524288 - ACTIVE
pl rootvol-01 rootvol ENABLED 524288 - ACTIVE
sd rootdisk01-03 rootvol-01 ENABLED 524288 0 -
pl rootvol-02 rootvol ENABLED 524288 - ACTIVE
sd rootdisk02-03 rootvol-02 ENABLED 524288 0 -
# vxplex -o rm dis rootvol-02
(Note that the TUTIL0 and PUTIL0 fields have been removed from the
vxprint output for readability.)
When the system has been repaired, and is in normal mode, the
following command can be used to remirror the root volume:
vxassist \-g rootdg mirror rootvol dm:rootdisk02
USAGE [Toc] [Back]
After VxVM has been started, various recovery options can be
performed. Exactly what recovery action needs to be performed depends
on what is wrong. It is recommended that you use vxprint to determine
the configuration state.
One common problem is when all the plexes of the root disk are stale.
This would appear in the configuration as:
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 -
sd rootdisk02-02 rootvol-02 ENABLED 393216 0 - -
When this happens, the volume can usually be repaired by using the
following command:
vxvol -g rootdg -f start rootvol
If the volume is mirrored, it is put in read-write-back recovery mode.
Since the command is run in the foreground, it does not exit until the
recovery is complete. Once this is complete, it is 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/rootdg/rootvol
mkdir /tmp_mnt
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vx_emerg_start(1M) VxVM 3.5 vx_emerg_start(1M)
1 Jun 2002
mount -F vxfs /dev/vx/dsk/rootdg/rootvol /tmp_mnt
SEE ALSO [Toc] [Back]
fsck(1M), mkdir(1M), mount(1M), vxintro(1M), vxprint(1M), vxvol(1M)
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