RE: [Linux-cluster] General FC Question

[Kovacs, Corey J.]

You don't say which FC cards you are using but if it's qlogic, then the
driver
can be set to combine the devices. Basically whats happened is that your
machine
is picking up the alternate path to the device, which is a perfectly valid
thing
to do, it's just not what you need at this point. It may be as simple as your

secondary controller actually has the lun you are trying to access. To work
around
yo might just be able to reset the seconday controller and force the primary
to take
over the LUN. This happens quite a bit depending on your setup. The Qlogic
drivers, 
when setup for failover, will coelesce the devices into a single device by
the WWID 
of the LUN. If that's not an option, then try the multipath tools support in
RHEL4.2 
or above. You won't be using the /dev/sd{a,b,c,...} devices, rather it'll be 
/dev/mpath/mpath0 etc, or whatever you set them to instead.

Even without failover, the latest Qlogic drivers will make both paths active
so that
you never end up with a dead path upon boot up.


Hope this helps.


Corey

-----Original Message-----
From: linux-cluster-bounces at redhat.com
[mailto:linux-cluster-bounces at redhat.com] On Behalf Of isplist at logicore.net
Sent: Monday, September 25, 2006 11:18 AM
To: linux-cluster
Subject: [Linux-cluster] General FC Question

After adding storage, my cluster comes up with different /dev/sda, /dev/sdb,
etc settings. My initial device now comes up as sdc when it used to be sda. 

Is there some way of allowing GFS to see the storage in some way that it can
know which device is which when I add a new one or remove one, etc?

Hard loop ID's on the FC side I think but is there anything on the GFS side?

Mike



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