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 vgscan(1M)							  vgscan(1M)




 NAME
      vgscan - scan physical volumes for LVM volume groups

 SYNOPSIS
      /usr/sbin/vgscan [-a] [-p] [-v]

 DESCRIPTION
      The vgscan command allows the re-creation of the /etc/lvmtab file and
      possibly the associated volume group device files.  This command
      should be run only in the event of a catastrophic error such as the
      deletion of the /etc/lvmtab file or the mismatch of names of the
      physical volumes in the /etc/lvmtab file to the actual physical volume
      path configuration.  If the /etc/lvmtab file exists, the information
      contained in the file is used to assist in rebuilding the file, but
      the existing file is updated with the new corrected configuration.

      vgscan searches each physical volume connected to the system, looking
      for logical volumes.  If there are dual controller devices, only the
      primary controller device path is scanned, unless you specify the -a
      option to allow access to all paths.  It groups these physical volumes
      into volume groups by matching the volume group information found on
      the physical volumes.  Then it searches the /dev directory for all
      group device files with the LVM major number, and tries to match
      device files with the logical volumes' information found on the
      physical volumes.

      If matches occur, it determines the volume group name from the device
      file path, and updates the /etc/lvmtab file with the volume group name
      and the list of physical volumes paths contained in that volume group.
      For volume groups where the device files cannot be matched, it prints
      the list of physical volumes for each volume group.

      After vgscan completes successfully, run the vgimport command on each
      set of unmatched physical volumes (see vgimport(1M)).

    Options
      vgscan recognizes the following options:

	   -a	Scan all controller device paths for all disks.

	   -p	Preview the actions that would be taken but do not update
		file /etc/lvmtab.  This option is best used in conjunction
		with the -v option.

	   -v	Print verbose messages.

 WARNINGS
      The following warning only applies to dual controller devices (NIKE),
      or disks with alternate path:





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 vgscan(1M)							  vgscan(1M)




      Since vgscan search each disks on the system in the order of where
      they have configured.  When vgscan reconstructs the /etc/lvmtab file,
      the order of disks in the file could be different than it was before.
      The following will happen:

	   The designated primary and alternate link might not be the same
	   as it was configured before.

	   Alternate links will be added to the /etc/lvmtab file even if
	   they might not be configured in the volume group initially.

	   The boot information might be incorrect due to different order of
	   disks in the new /etc/lvmtab file.

      In order to correct the above problems, do the following:

	   Use vgchange with -a option to activate all volume groups.

	   Use lvlnboot with -R option to correct boot information on disk.

	   Use vgreduce to reduce any alternate links that were added to the
	   /etc/lvmtab file by vgscan, but they were not needed.

	   If the original primary path of a disks become an alternate path
	   after /etc/lvmtab file is reconstructed, the order can be easily
	   reverted by using vgreduce to remove the primary path and use
	   vgextend to add the path back again.

      If /etc/lvmtab is destroyed, do not use vgscan to re-construct
      /etc/lvmtab if the system is heavily loaded by an application.
      Otherwise, vgscan will create an incomplete /etc/lvmtab due to a known
      NIKE/LVM limitation issue.  It's important to quiesce the logical
      volume's I/O before re-constructing the /etc/lvmtab.

      If for some reason, there is a need to re-construct /etc/lvmtab when
      the system is running production application, vgscan will create a
      partial /etc/lvmtab.  In this case, most of the primary paths should
      be included in the /etc/lvmtab.  Use vgextend to include any missing
      alternate paths in the VG.

 EMC DISK WARNINGS
      Starting at 10.20, the vgscan command is supporting additional EMC
      Symmetrix disk product functionality (see vgchgid(1M)).  The vgscan
      command will be enforcing a new rule such that only EMC disks with the
      same attributes can belong to the same volume group. Note that an EMC
      disk, without any of the additional attributes, can still be mixed
      with non-EMC disks in the same volume group.  Please consult your EMC
      Symmetrix documentation, if applicable.

 CROSS-CABINET VOLUME GROUP WARNINGS




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 vgscan(1M)							  vgscan(1M)




      On multi-cabinet V-Class systems, it is possible to create a volume
      group using physical volumes that are physically attached to different
      cabinets.	 However, due to limitations in the HP-UX boot sequence,
      such a cross-cabinet volume group cannot contain root, boot, swap, or
      dump logical volumes.  If vgscan discovers a cross-cabinet volume
      group that contains a root, boot, swap, or dump logical volume, it
      will not update the /etc/lvmtab file for that volume group.

 EXTERNAL INFLUENCES
    Environment Variables
      LANG determines the language in which messages are displayed.

      If LANG is not specified or is null, it defaults to "C" (see lang(5)).

      If any internationalization variable contains an invalid setting, all
      internationalization variables default to "C" (see environ(5)).

 EXAMPLES
      Scan the primary controller device paths for all the physical volumes
      on the system, but do not update the /etc/lvmtab file:

	   vgscan -p -v

      Scan all controller device paths to all physical volumes on the
      system:

	   vgscan -a -v

      Scan the primary controller device paths for all the physical volumes
      on the system and re-create /etc/lvmtab file:

	   vgscan -v

      The following messages will appear after /etc/lvmtab file is re-
      created.

	   *** LVMTAB has been created successfully.

	   *** If PV links are configured in the system

	   *** Do the following to resync information on disk.

	   *** #1.  vgchange -a y

	   *** #2.  lvlnboot -R

 SEE ALSO
      vgexport(1M), vgimport(1M).






 Hewlett-Packard Company	    - 3 -   HP-UX Release 11i: November 2000