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migrate(8)							    migrate(8)

NAME
       migrate	- Move a file or file pages to another volume in an AdvFS file
       domain

SYNOPSIS
       /usr/sbin/migrate [-p pageoffset] [-n pagecount] [-s  volumeindex]  [-d
       volumeindex] filename

OPTIONS
       Specifies  the volume index number of the volume to which the pages are
       to be migrated. You can determine the volume index number of  the  vol‐
       umes  in	 an AdvFS file domain by using the showfile -x command. If you
       do not specify the -d option, the AdvFS determines the  destination  of
       the file or the file pages.  The AdvFS moves the file or the file pages
       to any volume or volumes with available space.  Specifies the number of
       pages  to  migrate,  starting at the pageoffset value. The default page
       count is to EOF.	 If you do not specify the -n option, the migrate com‐
       mand  migrates  pages from the pageoffset value to the end of the file.
       Specifies the page offset of the first page to migrate. The first  page
       of  the	file  is  page 0. The default page offset is 0.	 If you do not
       specify the -p option, the migrate command migrates pages  starting  at
       page  0	of  the file.  Specifies the volume index number of the volume
       from which the pages are to be migrated.	 Use the showfile  -x  command
       to  determine  the  volume index number of the volumes in an AdvFS file
       domain.

	      If you specify the -s option and the volume  that	 contains  the
	      file does not contain any data extents of that file, the utility
	      returns success without taking any action.

	      You must use the -s option when you are migrating striped files.
	      You  can	move pages of a striped file or a stripe file segment,
	      which is the entire portion of a striped file  that  resides  on
	      the specified volume, to another volume.

OPERANDS
       Specifies  the  name  of the file or file pages to be migrated from the
       volume. The file can be simple or striped.

DESCRIPTION
       The migrate utility moves the  specified	 simple	 (unstriped)  file  to
       another	volume	in the same file domain.  The utility also moves pages
       of a simple file or pages of a striped file segment to  another	volume
       (or volumes, if necessary) within the file domain.

       There  are  no read/write restrictions when using this command, you can
       migrate a file while users are reading it, writing to it, or both. When
       direct I/O is enabled, the migrate operation may experience interrupts.
       In all other cases the migrate operation	 executes  without  disrupting
       file I/O.

       When  you  run the migrate utility with only the -p and -n options, the
       utility attempts to allocate destination pages contiguously on one des‐
       tination volume in the file domain.  If there are not enough free, con‐
       tiguous blocks to accomplish the move, the  utility  then  attempts  to
       allocate the pages to the next available blocks on the same volume.  If
       there are not enough free blocks on the same volume, the	 utility  then
       attempts to moves the file to the next available volume or volumes. The
       utility returns an error diagnostic if it cannot accomplish the move.

       You must use the -s, -n, and -p options in order to  move  pages	 of  a
       striped	file  from one volume to another. Only those pages assigned to
       the source volume are moved to the destination volume:	all  pages  in
       the file are not moved.

       You can use the migrate utility to move heavily accessed files or pages
       of files to a different volume in the file domain. Use the -d option to
       indicate a specific volume. Also, you can use the utility to defragment
       a specific file, because the migrate utility defragments a  file	 when‐
       ever possible.

NOTES
       The  migrate  utility  does not evaluate your migration decisions. As a
       result, you can move more than one striped file segment onto  the  same
       volume, which can defeat the purpose of striping the file.

       The  number  of	stripes is determined by the number of extent maps for
       the file although a map may point to more than one volume. If you  want
       to  change  the	number of stripes for the file, you must re-create the
       file with the desired number of stripes.

RESTRICTIONS
       You can only perform one migrate operation on the same file at the same
       time.  When  you	 migrate a striped file, you can only migrate from one
       source volume at a time.

       You must be the root user to use this utility.

EXIT STATUS
       The utility returns a value  of	0  (zero)  on  success,	 otherwise  it
       returns a nonzero value and an error diagnostic.

EXAMPLES
       The  following  examples	 perform  tasks using the migrate utility.  To
       migrate the simple file abc from its current volume to any other volume
       in the file domain, enter: # migrate abc To migrate the simple file abc
       from volume 1 of a file domain to volume 6 of a file domain,  enter:  #
       migrate -s 1 -d 6 abc To migrate pages 10 through 99 (that is, 90 pages
       starting at page 10) of the simple file abc from its current volume  to
       volume  2 of the file domain, enter: # migrate -p 10 -n 90 -d 2 abc The
       following example migrates all the pages of a file  that	 reside	 on  a
       specified volume. A file, stripe_1, is striped across Volumes 1, 2, and
       3 of a six-volume AdvFS file domain. To migrate the entire stripe  file
       segment	of  the	 stripe_1  file that is on volume 1 to volume 4 of the
       domain, enter: # migrate -s 1 -d 4 stripe_1 The following example moves
       some,  but  not	all,  file  pages  on  one volume of a striped file to
       another volume in the file domain. Use the showfile command with the -x
       flag to determine the volume index, the page count, and the page offset
       for the volume. Then specify the pages you want to migrate.

	      In this example the file str_file is striped across  three  vol‐
	      umes  (1,	 2, and 3)	 of a four volume file domain. To move
	      some of the pages from volume 2 to volume 4, first identify  the
	      page offset and the page count for the pages you want to move: #
	      showfile -x str_file
		  Id Vol PgSz Pages XtntType Segs SegSz	  I/O Perf File 6.8007
	      2	  16   123   stripe    3     8 async  69% str_file

		extentMap: 1
		  pageOff    pageCnt	volIndex    volBlock	blockCnt
			0	   8	       3       67312	     624
		       24	   8
		       48	   8
		       72	   8
		       96	   7
		      103	   1	       3       67952	      64
		      120	   3
		  extentCnt: 2

		extentMap: 2
		  pageOff    pageCnt	volIndex    volBlock	blockCnt
			8	   8	       4       67312	     352
		       32	   8
		       56	   6
		       62	   2	       4       67696	      64
		       80	   2
		       82	   6	       4       67856	      96
		      104	   8	       4       68080	     128
		  extentCnt: 4

		extentMap: 3
		  pageOff    pageCnt	volIndex    volBlock	blockCnt
		       16	   8	       1       76048	     256
		       40	   8
		       64	   8	       1       76320	     128
		       88	   8	       1       76544	     128
		      112	   8	       1       76720	     128
		  extentCnt: 4

	      The  showfile output shows that volume 4, as shown in extent map
	      2, contains a total of 40 pages of the striped file starting  at
	      page  offset  8.	You  want  to  migrate the first 16 pages that
	      reside on volume 4 to volume 2. The  first  eight	 pages	to  be
	      moved start at page offset 8 and end at page offset 15. The next
	      eight pages to be moved start at page offset 32 and end at  page
	      offset  39. So the range of pages you want to move (the value of
	      the -n flag) is 32 pages; that is,  8  to	 39  inclusive.	  (The
	      other  pages  in the range are on other volumes because the file
	      is striped.)  The command will migrate only the pages  from  the
	      specified	 volume	 in the specified range.  # migrate -p 8 -n 32
	      -s 4 -d 2 str_file

	      Because you did not move all of the pages from volume 4 to  vol‐
	      ume  2, the file is now stored on four volumes.  Note, that this
	      does not change the stripe width of the file.  There  are	 still
	      three extent maps.

	      To confirm the migration, reissue the showfile command.  Follow‐
	      ing is part of the output showing the new extent map 2:
		extentMap: 2
		  pageOff    pageCnt	volIndex    volBlock	blockCnt
			8	   8	       2       51920	     256
		       32	   8
		       56	   8	       4       68592	     256
		       80	   8
		      104	   8	       4       68080	     128
		  extentCnt: 4

SEE ALSO
       Commands: showfdmn(8), showfile(8), stripe(8)

       Files: advfs(4)

								    migrate(8)
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