[Linux-cluster] General FC Question

[isplist at logicore.net]

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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