RE: [Linux-cluster] General FC Question

[Kovacs, Corey J.]

I'd say LUN.  If you cat out /proc/scsi/scsi you'll see the luns are
repeated. The qlogic
based failover doesn't have anything to do with settings on the SAN
(combining luns etc)
it does it at the scsi layer (on the host). sort of like "secure path" from
HP. What you
are seeing is the presence of both paths by the driver. The RedHat qlogic
driver seems a
bit crippled since they'd (and the upstream kernel devs) would rather you
used the 
device mapper multipath solution instead.

The path of least resistence is to get the qlogic drivers from the qlogic
site (not the
stock redhat drivers) and install them.

A better long term solution is prolly to go ahead and figure out the
multipath device mapper
stuff.



Cheers.

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: Tuesday, September 26, 2006 9:46 AM
To: linux-cluster
Subject: RE: [Linux-cluster] General FC Question

PS: Is my problem hard loop ID's or LUN's? Could I achieve what I need either
way or is it one or thew other?


On Tue, 26 Sep 2006 07:44:00 -0400, Kovacs, Corey J. wrote:
> One more thing, when using more than one path (basically anyu san setup)
the
> 
> device
> mappings will wrap around for every path, so for two paths... single hba,
> dual controller..
> 
> 
> three disks will look like this...
> 
> disk1=/dev/sda
> disk2=/dev/sdb
> disk3=/dev/sdc
> disk1=/dev/sdd
> disk2=/dev/sde
> disk3=/dev/sde
> 
> and four like this..
> 
> disk1=/dev/sda
> disk2=/dev/sdb
> disk3=/dev/sdc
> disk4=/dev/sdd
> disk1=/dev/sde
> disk2=/dev/sde
> disk3=/dev/sdf
> disk4=/dev/sdg
> 
> 
> Or for dual hba, dual controller (4 paths)
> 
> 
> disk1=/dev/sda
> disk2=/dev/sdb
> disk3=/dev/sdc
> disk4=/dev/sdd
> disk1=/dev/sde
> disk2=/dev/sde
> disk3=/dev/sdf
> disk4=/dev/sdg
> disk1=/dev/sdh
> disk2=/dev/sdi
> disk3=/dev/sdj
> disk4=/dev/sdk
> disk1=/dev/sdl
> disk2=/dev/sdm
> disk3=/dev/sdn
> disk4=/dev/sdo
> 
> etc...
> 
> Cheers
> 
> With the Qlogic drivers in failover mode, you'll get this..
> 
> disk1=/dev/sda
> disk2=/dev/sdb
> disk3=/dev/sdc
> disk4=/dev/sdd
> 
> even though there are multiple paths
> 
> 
> Corey
> 
> -----Original Message-----
> From: linux-cluster-bounces at redhat.com
> [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Kovacs, Corey J.
> Sent: Tuesday, September 26, 2006 7:38 AM
> To: isplist at logicore.net; linux clustering
> Subject: RE: [Linux-cluster] General FC Question
> 
> 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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