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 vx_emerg_start(1M)		  VxVM 3.5		  vx_emerg_start(1M)
				 1 Jun 2002



 NAME
      vx_emerg_start - start VERITAS Volume Manager from recovery media

 SYNOPSIS
      vx_emerg_start [-f] [-m] [-r root_daname] hostname

 DESCRIPTION
      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
      -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
      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.



				    - 1 -	  Formatted:  August 2, 2006






 vx_emerg_start(1M)		  VxVM 3.5		  vx_emerg_start(1M)
				 1 Jun 2002



 NOTES
      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:





				    - 2 -	  Formatted:  August 2, 2006






 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
      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



				    - 3 -	  Formatted:  August 2, 2006






 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
      fsck(1M), mkdir(1M), mount(1M), vxintro(1M), vxprint(1M), vxvol(1M)

















































				    - 4 -	  Formatted:  August 2, 2006