Multipathing errors

Eugene Vilensky evilensky at gmail.com
Sun Feb 20 18:12:37 UTC 2011


On Sun, Feb 20, 2011 at 10:40 AM, Paul Crittenden
<paul.crittenden at simpson.edu> wrote:
> We are trying to set up multipathing RHEL 5.5 and are getting some errors. When I comment the 3 blacklist lines in the /etc/multipath.conf file and then run modprobe dm-multipath

Most documentation recommend using the service command or executing
/etc/init.d/multipathd in order to start/stop/restart the service.
Regardless, the "blacklist lines" are just examples for you to craft
your own as applicable to your machine configuration.

 >and turn on the multipathd daemon I am not seeing the mpath0 device
being created in the /dev/mapper folder.

What is "turn on the multipathd daemon" mean? Restart the service? Do
you follow up with any additional commands to verify what your change
accomplished?

>Also, in the /dev/ directory I see sda, sda1, sdb, sdb1, sdc, sdc1, sdd, sdd1 devices. I have another server that I have set up multipathing on and there are only sda, sdb, sdc and sdd devices and the mpath0 device is created and multipathing is working fine on it.

Your two systems are configured differently.  You didn't mention it
above, but what commands/outputs are you using to measure "working
fine" and not "working fine" ?


> When I reboot the server with the multipath daemon enabled and the device blacklist commands commented out, when it tries to then mount /dev/sda1 I get the error, /dev/sda1 already mounted or the mount point is busy. I then uncomment out the blacklist lines and everything is back to normal except I am still seeing the sda, sda1 etc. devices being created.

The blacklists are there as /examples/ of how to craft your own in
order to properly exclude non-multipath devices from the multipath
daemon.

You should probably start with this:
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html-single/DM_Multipath/index.html




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