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RE: [rhelv5-list] Interoperating with DS4800



>-----Original Message-----
>From: rhelv5-list-bounces redhat com 
>[mailto:rhelv5-list-bounces redhat com] On Behalf Of Troels Arvin
>Sent: Saturday, May 24, 2008 5:08 PM
>To: rhelv5-list redhat com
>Subject: [rhelv5-list] Interoperating with DS4800
>
>Hello,
>
>I've got a Dell server which has part of its storage served via fibre 
>channel from an IBM DS4800 storage unit (which has two 
>controllers). The 
>Dell server has a QLogic dual channel HBA.
>
>I've got basic multipathing set up, i.e. pairs of SCSI devices are 
>coalesced into single devices in /dev/mpath.
>
>However, when I use DS4800's management software to specify a new 
>preferred path, the server doesn't seem to respect it. Shortly 
>after such 
>a configuration change, a SAN alarm is thrown: "Logical Drive Not On 
>Preferred Path".
>
>Googling results in many different, somewhat conflicting 
>advice on how to 
>interact with a DS4800 system.
>http://www.ibm.com/developerworks/linux/library/l-multipath-xen
/ mentions 
>special add-on kernel driver software; I would very much like to stay 
>clear of such 3rd party kernel stuff.
>
>Does anyone have experiences with DS4800 SAN equipment in relationship 
>with RHEL 5 which they would like to share?

While I don't have any direct experience with RHEL 5, I'd tell you to
start with IBMs SAN compatibility guide and make sure that the
controller firmware and HBA driver are on the compat list.

I believe that IBM still pushes the RDAC driver for failover, but again
I don't have recent experience to the SAN compat guide should point to
the driver as well.
http://www-03.ibm.com/systems/storage/disk/ds4000/interop-matrix.html

I have a customer with VMware and a DS4300 dealing with the same issue,
and per IBM, it is a bug in the SAN firmware.  But the DS4300 is a
different class of storage, and there are other factors for them (EXP700
disk shelves).

Good luck!
Don


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