How to interpret fsadm -F vxfs -D -E [mount point] output

[Pat Smith]

Hi everyone,

I am considering a modification to our nightly backup scripts. This modification would run a directory and extent level fragmentation report and then, depending on the output of the report, schedule an extent and directory level online defrag.

My question is this...How do I interpret the output of fsadm -E -D? The report does not explicitly state the level of fragmentation but does give me a plethora of information regarding block size, free extents, etc,etc...

What information is important here and how do I measure it's importance?

[Vincent Stedema]

Hi,

The man page for fsadm_vxfs goes into details on how to determine whether extents and/or directories are fragmented. Here are a few snippets from the text:

>> fsadm_vxfs <<

Determining Fragmentation
To determine whether fragmentation exists for a given file system, the free extents for that file system need to be examined. If a large number small extents are free, then there is fragmentation. If more than half of the amount of free space is taken up by small extents (smaller than 64 blocks), or there is less than 5 percent of total file system space available in large extents, then there is serious fragmentation.


Measuring Directory Fragmentation
If the totals in the columns labeled "Dirs to Reduce" are substantial, a directory reorganization should improve performance of pathname resolution. The directories that fragment tend to be the directories with the most activity. A small number of fragmented directories may account for a large percentage of name lookups in the file system.

>> fsadm_vxfs <<

Hope this helps.

Vincent