topic Re: JFS Defragmentation in Operating System - HP-UX

JFS Defragmentation

Sebastien Masson — Wed, 21 Nov 2001 11:34:49 GMT

How good is it to run fsadm -D and fsadm -E to defragment directory and extents ?! This is need to run each day in a cron or just when I believe my file system is too busy ? and in this last case, that will increas the speed of it ?! Some discussion about that... thanks

Re: JFS Defragmentation

Paula J Frazer-Campbell — Wed, 21 Nov 2001 11:39:37 GMT

Hi

The old answer is "It Depends".

What are your file systems doing?
Is data being moved around.
Etc.

On a busy file system where there is lots of file movement then defragmentation will be higher than other quieter systems.

So do a defrag report - defrag - and then say a week later do another defrag report.

This will enable you to make your decision for your file systems.

HTH

Paula

Re: JFS Defragmentation

Vincent Farrugia — Wed, 21 Nov 2001 12:10:20 GMT

Hello,

Defragmentation is performed definitely before a file system reduction. I have never seen a large performance gain after defragmentation. Nowadays hardisks are so fast it's not noticable. But it's good practice to do it about once a month/2 months. It depends on the frequency of creation of new files.

HTH,
Vince

Re: JFS Defragmentation

Darrell Allen — Wed, 21 Nov 2001 14:15:22 GMT

Hi Sebastien,

I agree, definitely before trying to reduce the size of a filesystem (use both options). Otherwise I generally don't defrag. If I had filesystems with a lot of file creation, deletion, or modifications then I'd expect to defrag. It would be wise to gather stats on performance before and after to see what you actually gain then adjust your interval between defrags accordingly.

Darrell

Re: JFS Defragmentation

harry d brown jr — Wed, 21 Nov 2001 14:42:13 GMT

Because "It Depends", what are the type of files, typical file sizes, growth, deletion, etc on this filesystem?

live free or die
harry

Re: JFS Defragmentation

Craig Rants — Wed, 21 Nov 2001 14:52:32 GMT

Sebastien,
I think if HP thought it was important to defragment you system all on a constant basis they would probably give you that ability without having to buy software, then again...

If you are worried about disk I/O I would look at the way your disks are layed out, proper design would go much farther to improve disk I/O than defragmenting ever would.

Just my thoughts,
C