Using an EMC AX100 SAN with Debian and a Dell 1955 blade

[Stephen Carr]

Okay, I'm still working on this problem and am making progress but I've
run into a few snags that hopefully someone can help with. I've
simplified my SAN connections for now (until I have a chance to run some
extra cables to try what Harald mentioned) and things work well on that
front except two things. 
One of them is the boot timing issue (the device isn't "multipathed"
before fstab is called) that I'm working on by modifying a handy
workaround script from Stephan (if I get a Debian version working with
some English comments hopefully Stephan can release it) and the other is
that when I test a failover, the multipath device comes back fine but it
is remounted as Read-Only (since it is an ext3 formatted drive, it gets
journaling errors and does that automatically I assume).

Is there a way to not have the ext3 device remount Read-Only during a
failover? That would be a deal breaker for trying to run virtual OS's
from a SAN (for easy migration). Any thoughts would be helpful. I will
certainly put together a full HOWTO after this is all said and done for
anyone else who would like to go down this path (if I get it working ;-)
)

Stephen



-----Original Message-----
From: Stephan Wonczak [mailto:a0033 at rrz.uni-koeln.de] 
Sent: Monday, March 19, 2007 1:30 AM
To: linux-poweredge at lists.us.dell.com
Cc: Stephen Carr
Subject: RE: Using an EMC AX100 SAN with Debian and a Dell 1955 blade

   Hi Stephen!

On Fri, 16 Mar 2007, Stephen Carr wrote:

> okay, I will try setting this up (I do have some ports and cables to 
> play with). Thanks for the heads up. Then my last question would be 
> how to get these devices visible through multipath at boot so the 
> fstab can fsck it and mount it. Does anyone out there have any ideas 
> (I don't need to boot to the device, just have it come up on boot)?
<snip>

   We ran into exactly this problem, albeit with the IBM multipathing
driver. This also comes up rather late in the boot sequence and thus it
isn't possible to mount these devices via /etc/fstab.
   What we did however, was to write a special initscript that read
specially commented lines from /etc/fstab and mounts the appropriate
devices after the multipathing driver has come up.
   If you want a copy of this script contact me privately; it has some
rough edges that need additional explanation. Maybe after a second set
of eyes has looked over it, it may become fit for public consumption :-)

 	Dipl. Chem. Dr. Stephan Wonczak

         Zentrum fuer Angewandte Informatik (ZAIK)
         Regionales Rechenzentrum der Universitaet zu Koeln (RRZK)
         Universitaet zu Koeln, Robert-Koch-Strasse 10, 50931 Koeln
         Tel: ++49/(0)221/478-5577, Fax: ++49/(0)221/478-5590