topic Re: Defragmenting file system on HP-UX in Operating System - HP-UX

Defragmenting file system on HP-UX

Anil_29 — Wed, 07 Apr 2004 02:52:46 GMT

Hi,
I want to defrag /var filesystem online on a HP machine running B.10.20.

Are there any chances of data loss.

Thanks & Regards,
Anil

Re: Defragmenting file system on HP-UX

KapilRaj — Wed, 07 Apr 2004 02:56:59 GMT

defrag ??? Is this available in UNIX ??. I remember this term in DOS.

kiddin ....

I do not in HPUX but in AIX there is a command called defragfs .. Check for something similier in HPUX. Also logically it would not work if u do not have Online JFS

Regds,

Kaps

Re: Defragmenting file system on HP-UX

Mark Grant — Wed, 07 Apr 2004 02:58:01 GMT

Yes but no.

There is a chance of data loss but, to be honest I have never seen it happen. If you are at all nervous about this, take a backup first.

Re: Defragmenting file system on HP-UX

SureshKumar_2 — Wed, 07 Apr 2004 03:00:51 GMT

Hi anil

If u have HFS it is an optimised defragmentation.

Hope this url will help you

HFS :
http://aa11.cjb.net/hpux_admin/1997/0008.html

Online jFS :
http://unix.derkeiler.com/Mailing-Lists/HP-UX-Admin/2003-10/0029.html

regards
suresh

Re: Defragmenting file system on HP-UX

T G Manikandan — Wed, 07 Apr 2004 03:09:08 GMT

you should have Online JFS installed for this.

the extent fragmentation and directory fragmentation are specified by the -e and -d options of the fsadm command.

I would really recommend to take a ignite image backup before you do something on this system file system,.

First run -E & -E options to just view the report of fragmentation.

Re: Defragmenting file system on HP-UX

SANTOSH S. MHASKAR — Wed, 07 Apr 2004 03:15:38 GMT

Hi Anil,

Defragmenting of file system on HP_UX is definitely avaliable if the file system type is
vxfs or JFS. U can use following command

# fsadm -F vxfs -e -v /var

Also look for fsadm_vxfs man pages.

- Santosh

Re: Defragmenting file system on HP-UX

Anil_29 — Wed, 07 Apr 2004 03:18:13 GMT

Hi Manikanthan,

Thanks for all who replied.
Can u pls tell me if my /var file system requires defragmentation, I am pasting the output of "fsadm -F vxfs -D -E /var" command. cna can any one briefly explain the output.

# fsadm -F vxfs -D -E /var

Directory Fragmentation Report
Dirs Total Immed Immeds Dirs to Blocks to
Searched Blocks Dirs to Add Reduce Reduce
total 2830 1110 1956 51 55 104

Extent Fragmentation Report
Total Average Average Total
Files File Blks # Extents Free Blks
16150 31 1 42085
blocks used for indirects: 326
% Free blocks in extents smaller than 64 blks: 47.79
% Free blocks in extents smaller than 8 blks: 34.40
% blks allocated to extents 64 blks or larger: 75.81
Free Extents By Size
1: 635 2: 477 4: 404 8: 78
16: 17 32: 11 64: 8 128: 6
256: 6 512: 2 1024: 1 2048: 0
4096: 0 8192: 0 16384: 0 32768: 1

Thanks & Regards,
Anil

Re: Defragmenting file system on HP-UX

Jim Mallett — Wed, 07 Apr 2004 06:02:11 GMT

Anil,

man 1m fsadm_vxfs has a section that explains most of fields and values.

In most cases, a smaller number is better.
Important fields to look at are:
Immeds to Add
Dirs to Reduce
Blocks to Reduce
Avg # Extents
%Free in smaller than 64 blocks
%Free in smaller than 8 blocks

I schedule a defrag for all vxfs file systems monthly. To give you an example of what my /var looks like:

Directory Fragmentation Report
Dirs Total Immed Immeds Dirs to Blocks to
Searched Blocks Dirs to Add Reduce Reduce
10052 725 9469 1 8
27
Extent Fragmentation Report
Total Average Average Total
Files File Blks # Extents Free Blks
19342 31 1 1474780
blocks used for indirects: 24
% Free blocks in extents smaller than 64 blks: 2.29
% Free blocks in extents smaller than 8 blks: 0.16
% blks allocated to extents 64 blks or larger: 82.06

HP suggests "%Free blocks in extents smaller than 64 blocks" be less than 50%, your # is approaching that. In most cases you're not going to run a defrag and say "Wow, what an improvement." But even small improvements over time can help out the big picture. Although a defrag can be run at any time, there will be a performance hit while it is happening so keep that in mind if users are accessing the system. I just schedule mine off hours.

Jim

Re: Defragmenting file system on HP-UX

Bill Hassell — Wed, 07 Apr 2004 07:30:43 GMT

As mentioned, you will not see a significant improvement in speed at all. The VxFS filesystem does a good job in keeping file fragmentation to a minimum. Your first step in managing /var should be to implement an automated removal of unnecessary and temporary files in /var/tmp and trimming or archiving logfiles in /var/adm. Similarly, the cleanup command is needed to manage patches and of course, junk (forgooten data) in /var/mail and /var/spool are always a problem. And if your system has crashed, there may be crash dumps in /var/adm/crash. Do this to locate the trouble areas:

du -kx /var | sort -rn | more

Re: Defragmenting file system on HP-UX

dirk dierickx — Thu, 08 Apr 2004 01:30:41 GMT

some unix fs have this option, however its impact will be minimal, the unix fs is already optimized.