defragment(8)						      System Manager's Manual						     defragment(8)

NAME

       defragment - Makes the files in a file domain more contiguous

SYNOPSIS

       /usr/sbin/defragment [-e] [-n] [-N threads] [-t time] [-T time] [-v] [-V] domain

OPTIONS

       Ignores errors and continues, if possible. Errors that are ignored are usually related to a specific file.  Specifies the number of threads
       to run on the utility.  The default number of threads that will be run is the number of volumes in the domain.  The maximum number you  can
       specify	for  the  number  of threads is 20.  Prevents defragmentation from actually taking place. Use in conjunction with the -v option to
       display statistics on the number of extents in the file domain.	Specifies a flexible time interval (in minutes) for the defragment utility
       to  run. If the utility is performing an operation when the specified time has elapsed, the procedure continues until the operation is com-
       plete.  Specifies an exact time interval (in minutes) for the defragment utility to run. When the specified time has elapsed,  the  defrag-
       mentation  procedure  stops,  even if it is performing an operation.  Displays statistics on the amount of fragmentation in the file domain
       and information on the progress of the defragment procedure.  Displays the same information provided by the -v option along  with  informa-
       tion about each operation the defragment utility performs on each file.	This option slows the defragment procedure.

OPERANDS

       Specifies the name of the file domain.

DESCRIPTION

       When a file consists of many discontiguous file extents, the file is fragmented on the disk. File fragmentation reduces the read/write per-
       formance because more I/O operations are required to access a fragmented file.

       The defragment utility attempts to reduce the number of file extents in a file domain by making files more contiguous. Defragmenting a file
       domain often makes the free space on a disk more contiguous, resulting in less fragmented file allocations in the future.

       Before  you  can  defragment a file domain, all filesets in the file domain must be mounted. If you try to defragment an active file domain
       that includes unmounted filesets, the system displays an error message indicating that a fileset is unmounted.

       To determine the amount of file fragmentation in a file domain, run the defragment command with the -v and -n options.  This  provides  the
       fragmentation information without starting the defragmentation process. Run defragment with the -v and -n options again to see the improve-
       ment.

       Before running the defragment utility, delete any files in the domain that you do not need. This gives the  defragment  utility	more  free
       space  to  use, which produces better results.  Deleting files afterwards creates only more free-space fragments. It is also a good idea to
       run the balance utility on the domain before you run the defragment utility in order to balance domain free space before defragmenting  the
       domain files.

       To monitor the improvement made to the file domain by the defragment utility, use the verbose mode option, -v, which displays the following
       information: Extents

	      The number of extents in the specified domain. (Contiguous extents in sparse files are counted as one extent after  defragmentation,
	      when in fact there are several contiguous file extents.)	Files w/ extents

	      The  number  of files that have extents. (Note that files do not have extents if the files are less than 7 Kilobytes.)  Avg exts per
	      file w/ exts

	      The average number of extents for each file that has one or more extents.  Aggregate I/O perf

	      The efficiency of the entire file domain. An increase in value indicates improvement.  Free space fragments

	      The number of free-space fragments in the domain.

RESTRICTIONS

       The defragment utility requires a minimum of 1 percent of the total space, or 5 megabytes per volume (whichever is  less)  to  be  free	in
       order to run.

       You cannot run the defragment utility while the addvol, balance, defragment, rmfset, or rmvol utility is running on the same file domain.

       You must be the root user to use this utility.

EXAMPLES

       The  following  example defragments the file domain called accounts_dmn. A flexible time limit of 15 minutes is imposed and verbose mode is
       requested to display the fragmentation data: # defragment -v -t 15 accounts_dmn

       defragment: defragmenting domain 'accounts_dmn'

       Pass 1; Clearing

	 Volume 1: area at block    11680 (  103072 blocks): 81% full
	 Domain data as of the start of this pass:
	   Extents:		     10432
	   Files w/extents:	      4305
	   Avg exts per file w/exts:  2.42
	   Aggregate I/O perf:	       52%
	   Free space fragments:      2743
			    <100K    <1M    <10M    >10M
	     Free space:     38%      0%      0%     62%
	     Fragments:     2742       0       0       1

       Filling .  .  .	Pass 13; Clearing
	 Volume 1: area at block   559744 (   62736 blocks):  0% full
	 Volume 2: area at block    76640 (   24624 blocks): 18% full
	 Domain data as of the start of this pass:
	   Extents:		      4306
	   Files w/extents:	      4305
	   Avg exts per file w/exts:  1.00
	   Aggregate I/O perf:	      100%
	   Free space fragments:	23
			    <100K    <1M    <10M    >10M
	     Free space:      0%      9%     27%     64%
	     Fragments:        6      10       5       2

       Filling

	 Current domain data:
	   Extents:		      4305
	   Files w/extents:	      4305
	   Avg exts per file w/exts:  1.00
	   Aggregate I/O perf:	      100%
	   Free space fragments:	17
			    <100K    <1M    <10M    >10M
	     Free space:      0%      6%     29%     65%
	     Fragments:        3       8       4       2

       defragment: defragmented domain 'accounts_dmn'

       The information displayed before each pass and at the conclusion of the defragmentation process shows the  improvement  made  to  the  file
       domain by the defragment utility.

SEE ALSO

       Commands: addvol(8), balance(8), rmvol(8)

																     defragment(8)