Multipath Fibrechannel interface to SAN under Ubuntu
	Part X. Debian (sometimes also Ubuntu)

Multipath Fibrechannel interface to SAN under Ubuntu

Jurjen Bokma

February 2008

apt-get install multipath-tools
Edited /etc/multipath.conf:
```
defaults {
polling_interval    30
failback            immediate
no_path_retry       5
rr_min_io           100
path_checker        tur
user_friendly_names yes
}

multipaths {
multipath {
wwid 360050768019101ca2800000000000031
alias IBM-2145
}
}
	
```
multipath -l now gives:

IBM-2145 (360050768019101ca2800000000000031) dm-4 IBM,2145 [size=2.0T][features=1 queue_if_no_path][hwhandler=0] \_ round-robin 0 [prio=0][enabled] \_ 3:0:0:0 sdb 8:16 [active][undef] \_ round-robin 0 [prio=0][enabled] \_ 3:0:1:0 sdc 8:32 [active][undef]
Now, /dev/sdc, which we used to mount, is in use by multipathd, and we cannot mount it any more.
/etc/init.d/multipath-tools restart
mount -t xfs /dev/disk/by-id/dm-uuid-mpath-360050768019101ca2800000000000031 /srv/linux/ runs forever with no CPU load, and cannot be killed, so I think it is waiting for I/O.
/bin/sh -f /usr/sbin/xfs_check /dev/disk/by-uuid/../../mapper/IBM-2145 also ends up waiting for I/O.
Furthermore, /var/log/daemon.log reads:

... Feb 23 18:06:16 si17 multipathd: 8:16: mark as failed Feb 23 18:06:17 si17 multipathd: 8:32: mark as failed Feb 23 18:06:46 si17 multipathd: 8:16: reinstated Feb 23 18:06:46 si17 multipathd: 8:16: mark as failed Feb 23 18:06:47 si17 multipathd: 8:32: reinstated Feb 23 18:06:47 si17 multipathd: 8:32: mark as failed Feb 23 18:07:16 si17 multipathd: 8:16: reinstated Feb 23 18:07:16 si17 multipathd: 8:16: mark as failed Feb 23 18:07:17 si17 multipathd: 8:32: reinstated Feb 23 18:07:17 si17 multipathd: 8:32: mark as failed Feb 23 18:07:46 si17 multipathd: 8:16: reinstated Feb 23 18:07:46 si17 multipathd: 8:16: mark as failed Feb 23 18:07:47 si17 multipathd: 8:32: reinstated Feb 23 18:07:47 si17 multipathd: 8:32: mark as failed Feb 23 18:08:16 si17 multipathd: 8:16: reinstated Feb 23 18:08:16 si17 multipathd: 8:16: mark as failed Feb 23 18:08:17 si17 multipathd: 8:32: reinstated Feb 23 18:08:17 si17 multipathd: 8:32: mark as failed Feb 23 18:08:46 si17 multipathd: 8:16: reinstated Feb 23 18:08:46 si17 multipathd: 8:16: mark as failed Feb 23 18:08:47 si17 multipathd: 8:32: reinstated Feb 23 18:08:47 si17 multipathd: 8:32: mark as failed

And multipath -l now gives:

IBM-2145 (360050768019101ca2800000000000031) dm-4 IBM,2145 [size=2.0T][features=1 queue_if_no_path][hwhandler=0] \_ round-robin 0 [prio=0][enabled] \_ 3:0:0:0 sdb 8:16 [failed][undef] \_ round-robin 0 [prio=0][enabled] \_ 3:0:1:0 sdc 8:32 [failed][undef]

(It seems to cycle through “failed” and “active”.)
Also, after /etc/init.d/multipath-tools stop, I/O still fails on both /dev/sdc and /dev/sdb. And when the multipath-tools are running, I/O fails on /dev/mapper/IBM-2145.
Rebooting solves. We can now at least mount /dev/mapper/IBM-2145 read-only. Still it is a Windows solution. And I don't understand what went wrong.
And now the problem is back: the filesystem on /dev/mapper/IBM-2145 is mounted read-only (and without filesystem cehck) on /srv/linux, but both a find on the mount point and an xfs_check on the block device end up waiting for I/O.
And this time, rebooting ends with a machine that responds to ping, but nothing else. I have no idea whether it hangs in shutdown (the unmount?) or didn't come up properly.

	Note
	Arjan solved this one. It turns out that the add-in card was broken. He replaced it with a new one, and in the process replaced the entire server too.

	Note
	This was something of a bad start, but things got better. The rest of this adventure is in http://www.cs.rug.nl/~jurjen/iwi-howtos/linux/Osis.


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