FYI
http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/B3929-90011/B3929-90011_top.html&con=/hpux/onlinedocs/B3929-90011/00/00/18-con.html&toc=/hpux/onlinedocs/B3929-90011/00/00/18-toc.html&searchterms=fsadm&queryid=20010316-052424Monitoring Fragmentation
Fragmentation reduces performance and availability. Regular use of fsadm's fragmentation reporting and reorganization facilities is therefore advisable.
The easiest way to ensure that fragmentation does not become a problem is to schedule regular defragmentation runs from cron.
Defragmentation scheduling should range from weekly (for frequently used file systems) to monthly (for infrequently used file systems). Extent fragmentation should be monitored with fsadm_vxfs(1M) or the -o s options of df_vxfs(1M). There are three factors which can be used to determine the degree of fragmentation:
percentage of free space in extents of less than eight blocks in length
percentage of free space in extents of less than 64 blocks in length
percentage of free space in extents of length 64 blocks or greater
An unfragmented file system will have the following characteristics:
less than 1 percent of free space in extents of less than eight blocks in length
less than 5 percent of free space in extents of less than 64 blocks in length
more than 5 percent of the total file system size available as free extents in lengths of 64 or more blocks
A badly fragmented file system will have one or more of the following characteristics:
greater than 5 percent of free space in extents of less than 8 blocks in length
more than 50 percent of free space in extents of less than 64 blocks in length
less than 5 percent of the total file system size available as free extents in lengths of 64 or more blocks
The optimal period for scheduling of extent reorganization runs can be determined by choosing a reasonable interval, scheduling fsadm runs at the initial interval, and running the extent fragmentation report feature of fsadm before and after the reorganization.
The "before" result is the degree of fragmentation prior to the reorganization. If the degree of fragmentation is approaching the figures for bad fragmentation, then the interval between fsadm runs should be reduced. If the degree of fragmentation is low, the interval between fsadm runs can be increased.
The "after" result is an indication of how well the reorganizer is performing. The degree of fragmentation should be close to the characteristics of an unfragmented file system. The file system may be a candidate for expansion. (Full file systems tend to fragment and are difficult to defragment.) It is also possible that the reorganization is not being performed at a time during which the file system in question is relatively idle.
Directory reorganization is not nearly as critical as extent reorganization, but regular directory reorganization will improve performance. It is advisable to schedule directory reorganization for file systems when the extent reorganization is scheduled. The following is a sample script that is run periodically at 3:00 A.M. from cron for a number of file systems:
outfile=/tmp/fsadm_out.&212#;/bin/date +'%m%d'&212#;
for i in /home /home2 /project /db
do
/bin/echo "Reorganizing $i"
/bin/timex fsadm -F vxfs -e -E -s $i
/bin/timex fsadm -F vxfs -s -d -D $i
done > $outfile 2>&1
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