source: gpfs_3.1_ker2.6.20/share/man/man8/mmdefragfs.8 @ 90

.TH mmdefragfs 02/16/06
mmdefragfs Command
.SH "Name"
.PP
\fBmmdefragfs\fR - Reduces disk fragmentation by increasing the
number of full free blocks available to the file system.
.SH "Synopsis"
.PP
\fBmmdefragfs\fR \fIDevice\fR [\fB-i\fR]
[\fB-v\fR] [\fB-u\fR \fIBlkUtilPct\fR]
.SH "Description"
.PP
Use the \fBmmdefragfs\fR command to reduce fragmentation of a file
system. The \fBmmdefragfs\fR command moves existing file system data
within a disk to make more efficient use of disk blocks. The data is
migrated to unused subblocks in partially allocated blocks, thereby increasing
the number of free full blocks.
.PP
The \fBmmdefragfs\fR command can be run against a mounted or unmounted
file system. However, best results are achieved when the file system is
unmounted. When a file system is mounted, allocation status may change
causing retries to find a suitable unused subblock.
.PP
If \fBmmdefragfs\fR is issued on a file that is locked by SANergy, the file
is not de-fragmented.
.SH "Parameters"
.PP
.RS +3
\fB\fIDevice\fR
\fR
.RE
.RS +9
The device name of the file system to have fragmentation reduced.
File system names need not be fully-qualified. \fBfs0\fR is as
acceptable as \fB/dev/fs0\fR.
.PP
This must be the first parameter.
.RE
.SH "Options"
.PP
.RS +3
\fB-i
\fR
.RE
.RS +9
Specifies to query the current disk fragmentation state of the file
system. Does not perform the actual defragmentation of the disks in the
file system.
.RE
.PP
.RS +3
\fB-u \fIBlkUtilPct\fR
\fR
.RE
.RS +9
The average block utilization goal for the disks in the file
system. The \fBmmdefragfs\fR command reduces the number of allocated
blocks by increasing the percent utilization of the remaining blocks.
The command automatically goes through multiple iterations until
\fIBlkUtilPct\fR is achieved on all of the disks in the file system or
until no progress is made in achieving \fIBlkUtilPct\fR from one iteration
to the next, at which point it exits.
.RE
.PP
.RS +3
\fB-v
\fR
.RE
.RS +9
Specifies that the output is verbose.
.RE
.SH "Exit status"
.PP
.PP
.RS +3
\fB0
\fR
.RE
.RS +9
Successful completion.
.RE
.PP
.RS +3
\fBnonzero
\fR
.RE
.RS +9
A failure has occurred.
.RE
.SH "Security"
.PP
You must have root authority to run the \fBmmdefragfs\fR command.
.PP
You may issue the \fBmmdefragfs\fR command from any node in the GPFS
cluster.
.PP
When using the \fBrcp\fR and \fBrsh\fR commands for remote
communication, a properly configured \fB.rhosts\fR file must exist
in the root user's home directory on each node in the GPFS
cluster. If you have designated the use of a different remote
communication program on the
\fBmmcrcluster\fR or the
\fBmmchcluster\fR command, you must ensure:
.RS +3
.HP 3
1. Proper authorization is granted to all nodes in the GPFS cluster.
.HP 3
2. The nodes in the GPFS cluster can communicate without the use of a
password, and without any extraneous messages.
.RE
.SH "Examples"
.RS +3
.HP 3
1. To query the fragmentation state of file system \fBfs0\fR, issue this
command:
.sp
.nf
mmdefragfs fs0 -i
.fi
.sp
.sp
The system displays information similar to:
.sp
.nf
                         free subblk    free\ 
disk            disk size  in full  subblk in      %       %
name          in nSubblk   blocks   fragments free blk blk util
--------------- --------- --------- --------- --------  -------
gpfs68nsd         4390912   4270112       551   97.249   99.544
gpfs69nsd         4390912   4271360       490   97.277   99.590
                --------- --------- ---------           -------
(total)           8781824   8541472      1041            99.567
.fi
.sp
.HP 3
2. To reduce fragmentation of the file system \fBfs0\fR on all defined,
accessible disks that are not stopped or suspended, issue this command:
.sp
.nf
mmdefragfs fs0\ 
.fi
.sp
.sp
The system displays information similar to:
.sp
.nf
                     free subblk           free
  disk                in full            subblk in       %            %
  name               blocks    blk       framents     free blk     blk util
              before     after freed   before after before after before after
 ----------  ------------------------ ------------- ------------ ------------
  gpfs57nsd    28896     29888     31    1462   463  50.39 52.12  94.86 98.31
  gpfs60nsd    41728     43200     46    1834   362  59.49 61.59  93.55 98.66
             ---------------------  --------------               -----------
 (total)      70624     73088    77     3296      825             93.63 98.84
.fi
.sp
.HP 3
3. To reduce fragmentation of all files in the file system \fBfs1\fR
until the disks have an average block utilization percentage higher then 99%,
issue this command:
.sp
.nf
mmdefragfs fs1 -u 99\ 
.fi
.sp
.sp
The system displays information similar to:
.sp
.nf
WARNING: "fs1" is mounted on 1 nodes(s) and in use on 1 node(s)
       Start processing: iteration 1 Processing Pass 1 of 1
       Disk Name gpfs57nsd gpfs60nsd
   6 % complete
  12 % complete
  32 % complete
  38 % complete
  43 % complete
  75 % complete
  81 % complete
  92 % complete
  98 % complete
                   free subblk              free
  disk               in full              subblk in        %           %
  name               blocks     blk       fragments      free blk   blk util
              before     after freed   before  after before after before after\ 
  ----------  ------------------------ -------------- ------------ ------------
  gpfs57nsd     39424     40064    20     1347    589  68.75 69.87  92.48 96.59
  gpfs60nsd     50688     51456    24     1555    593  72.26 73.36  92.01 96.83\ 
               ---------------------  --------------               ------------
  (total)      90112     91520    44     2902    1182             93.63 98.84
.fi
.sp
.RE
.SH "See also"
.PP
mmdf Command
.SH "Location"
.PP
\fB/usr/lpp/mmfs/bin\fR
.PP