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High i/o on lunpath

jpcalgary
Occasional Visitor

High i/o on lunpath

Hi

I'm having high i/o on disk/lunpath even when the filesystem is unmounted/mounted.

Any ideas why?

root@hnamht11:/> fuser /backup
/backup:
root@hnamht11:/> umount /backup
root@hnamht11:/> iostat | awk '{print $2 " " $1}'| sort -n |tail -1
4068 disk274
root@hnamht11:/> mount /backup
root@hnamht11:/> bdf /backup
Filesystem kbytes used avail %used Mounted on
/dev/backupvg/bck11lv01
937164800 813538807 115899434 88% /backup
root@hnamht11:/> vgdisplay -v|egrep 'backupvg|disk274'
VG Name /dev/backupvg
LV Name /dev/backupvg/bck11lv01
PV Name /dev/disk/disk274
8 REPLIES
Turgay Cavdar
Honored Contributor

Re: High i/o on lunpath

Can you send us some sar output when the file system is unmounted?

sar -d 5 5

Are there any other logical volume in the /dev/disk/disk274?

Are there any disk activity when you both umount the file system and make the volume group offline?
Kapil Jha
Honored Contributor

Re: High i/o on lunpath

how many disks are there in the VG abd yuo may have to check if this disk has any other LV.

BR,
Kapil+
I am in this small bowl, I wane see the real world......
Michael Steele_2
Honored Contributor

Re: High i/o on lunpath

What does:

# lsof +D /directory

,,,reveal? (* Note: Might +L as well for +D /dir +L *)

Also, this is an indication of a runaway process, where the Parent PPID is dead but the child PID is still alive, orphaned but not zombied and still writing.

You may have to reboot if you can't find it.

This also works, create a 'new' reference file with the most recent time stamp on the system

# touch /var/tmp/myref
# find /apps -xdev -type f -newer /var/tmp/myref

...-newer will now display all files written to after the 'new' reference file. So if you do have a runaway process, you'll catch it in the act.
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jpcalgary
Occasional Visitor

Re: High i/o on lunpath

sar -d 5 5 does not show that disk with any activity- strange, one of them has to be incorrect.

There is multiple disks in the VG, and only one logical volume.
Turgay Cavdar
Honored Contributor

Re: High i/o on lunpath

Hi,
For monitoring disk performance sar and glance are major tools for me. I never use iostat, i dont know how accurate it is...
jpcalgary
Occasional Visitor

Re: High i/o on lunpath

If I offline the VG, the io stops- once I bring it online, the io begins; only in iostat, not in sar.
Michael Steele_2
Honored Contributor

Re: High i/o on lunpath

Hi

Use iostat on Ia64 based system, it does not work on PA-Risc systems. 'Sar' is reliable on both, as is glance.

Please paste in the sar -d 5 5 report. A disk bottleneck is defined when avwait > avserv, a phenomena usually always seen on vg00'd disks, (* o/s disks *), but not else where.
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Duncan Edmonstone
Honored Contributor

Re: High i/o on lunpath

I vaguely remember reading an internal article which indicated that running iostat with no further options produced numbers that totalled IO since the system was rebooted, and that even if you did:

iostat 10 10

the first set of numbers produced were meaningless...

so I would guess the numbers ypu are getting from iostat are incorrect for what you are looking at...

If only the man page was clearer...

HTH

Duncan

HTH

Duncan