topic Re: DM Multipath in Operating System - Linux

DM Multipath

John Guster — Mon, 13 Apr 2009 13:41:18 GMT

#mutilpath -l shows
mpath4 (xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx)
[size=30 GB][features="0"][hwhandler="0"] \_ round-robin 0 [active]
\_ #:#:#:# - 4:12 [failed]
\_ 3:0:1:7 sde 4:40 [active]

# multipath -v2
remove: mpath4 (wwid changed)
mpath4: map in use
how to clear this failed path? Storage guy says a reboot is needed.

Re: DM Multipath

Ivan Ferreira — Mon, 13 Apr 2009 13:55:02 GMT

Please see:

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1326622

Â¿How is that the wwid changed for that device?

Re: DM Multipath

John Guster — Mon, 13 Apr 2009 14:09:30 GMT

Storage guy removed that path but still allow this LUN being used by the system. is wwid supposed be changed when # of paths is reduced?

Re: DM Multipath

Ivan Ferreira — Mon, 13 Apr 2009 14:17:31 GMT

No, I'm not sure of the problem, but it may report wwid changed because the path is not there anymore, or another LUN was detected on that place.

Anyway, you shold keep at least two paths to the LUN.

Re: DM Multipath

John Guster — Mon, 13 Apr 2009 14:29:24 GMT

there is another path. looks like a reboot is needed. Do you think so?

Re: DM Multipath

Steven McCoy — Mon, 13 Apr 2009 15:06:41 GMT

Path issues typically clear up for me after a reboot. What does your /etc/multipath.conf file look like?

Re: DM Multipath

Ivan Ferreira — Mon, 13 Apr 2009 15:14:30 GMT

Maybe you need to rescan your disks. Have you rescanned your disks after the LUN maintenance?

Re: DM Multipath

John Guster — Mon, 13 Apr 2009 16:29:36 GMT

not sure what is rescan mean? can you provide more detail?

Re: DM Multipath

Steven McCoy — Mon, 13 Apr 2009 16:57:05 GMT

echo "- - -" > /sys/class/scsi_host/host0/scan
echo "- - -" > /sys/class/scsi_host/host1/scan

Where 'host0' is the first fiber card, 'host1' is the second, etc.

Make sure to have a 'tail -f' going on /var/log/messages when you run the command so you can spot possible issues.

If a redetect doesn't work, I'd suggest a reboot, unfortunately.

Hope this helps.

Re: DM Multipath

John Guster — Mon, 13 Apr 2009 18:36:20 GMT

it didn't do the trick.
does it need
echo "1">/sys/class/fc_host/host2/issue_lip
before echo "---"> /sys/class/scsi_host/host0/scan?

Re: DM Multipath

Steven McCoy — Mon, 13 Apr 2009 19:23:31 GMT

What does this say?:

ls /dev/disk/by-id/

Also, would you mind posting your /etc/multipath.conf file, please?

Re: DM Multipath

Tony Cicone — Tue, 14 Apr 2009 19:43:14 GMT

Can you flush the device?

multipath -F

How about deleting the sd device associated with mpath4?

echo "1" > /sys/block//device/delete

It should be deleted now.

ls -l /dev/sd*

Rescan for drives.

echo "1" > /sys/class/fc_host/host0/issue_lip
echo "1" > /sys/class/fc_host/host1/issue_lip

See if they show up.

ls -l /dev/sd*

Re-run the multipath commands.

multipath -v2
multipath -ll

Re: DM Multipath

John Guster — Tue, 28 Apr 2009 15:10:48 GMT

a reboot cleared all. Thanks.