Labeling Multipath drives

[Kenny Lussier]

On Wed, Mar 18, 2009 at 10:18 AM, Jeffrey O'brien
<JObrien at expertserver.com>wrote:

>
>
> >>>
> From:   Kenny Lussier <klussier at gmail.com>
> To:     mark <prgrmr at gmail.com>
> CC:     <gnhlug-discuss at gnhlug.org>
> Date:   3/18/2009 9:40 AM
> Subject:        Re: Labeling Multipath drives
>
> This is true. For example, in /dev/mapper there is a device called
> 350002ac00092072a1. I can label the device, but that also creates labels on
> what the OS sees as /dev/sdc, /dev/sdd, /dev/sde, /dev/sdf, /dev/sdg,
> /dev/sdh, /dev/sdi, and /dev/sdj, so a mount fails. The SAN doesn't come
> with client-side multipathing software. That is really up to the OS vendor.
> In this case, I am using device-mapper-multipath on RHEL5.3AP (w/ their
> clustering suite) with a 3Par SAN. The SAN is presenting all of the paths to
> both systems simultaneously. That isn't a problem. And, if I wanted to use
> GFS to have the disk mounted to both servers simultaneously, then that would
> work just fine. But, I can't have the disk mounted on more then one system
> at any given time.
>
>
> >>>
>
>
> http://www.scribd.com/doc/2673197/Using-DeviceMapper-Multipath-Configuration-and-Administration-for-Red-Hat-Enterprise-Linux-51
>
> Here is a redhat doc on 5.1, it should be relevant still.  You have to
> reference and format the mpath device instead of the individual device.
>  Also make sure the dm-multipath kernel module is loaded and the daemons are
> running.  Do you have the /etc/multipath.conf configured?
>
> Cheers,
> Jeff
>


Yup, multipath is configured correctly, and it all works. I can yank the
fiber out of one HBA and watch 4 paths fail, and continue to read/write to
the device, plug the fiber back in, and watch the 4 paths recover, etc. I
may need to do some more experiments to get this all to work. I think that
there may be an issue in the way that the QLogic driver is behaving.

Thanks,
Kenny
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