RE: [dm-devel] Changing SAN vendors

["Allen, Jack" <Jack Allen mckesson com>]

-----Original Message-----
From: Bryn M. Reeves [mailto:bmr redhat com] 
Sent: Friday, February 13, 2009 5:29 AM
To: device-mapper development
Subject: Re: [dm-devel] Changing SAN vendors

Allen, Jack wrote:
> Hello:
>     Still looking for an answer for RH AS 4.7.
>  
>     No body has any ideas?

The mpath names change because the XP is exporting the storage with 
new WWIDs (multipath-tools name binding is all based on LUN WWIDs). 
The bindings are stored in a file that is normally automatically 
generated and maintained.

I think in your stiuation if you need to preserve the old names, your 
best option is to manually edit the bindings file and copy it between 
the hosts that need to have a common view of the storage.

The default location for the file is /var/lib/multipath/bindings, 
although if you have /var configured as a separate file system you 
should move it to /etc and configure the bindings_file option in 
multipath.conf to avoid problems when initialising multipath devices 
before /var is mounted.

You could also take the steps that Tore suggested and configure 
multipath entries in multipath.conf to map the devices but unless you 
are happy with giving them new names this isn't going to work as the 
current multipath-tools will give undefined behaviour if you use 
"mpathN" style names for aliases defined in multipath.conf.

Regards,
Bryn.

===========================================
Thanks.

I do have /var as a separate file system and as you said it may not be
mounted when multipathd first starts. I will mv the bindings file to
/etc and make the change in multipath.conf.

-----
Thanks:
Jack Allen