[Linux-cluster] General FC Question
isplist at logicore.net
isplist at logicore.net
Tue Sep 26 13:35:36 UTC 2006
> 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..
Right, and of course, this is what's happened. New disks have shown up and the
old disk now shows up as a new device number.
By the way, is there a way to clear everything in the LVM2 cache and setup
info? It is now confused and seeing a lot of trashed information. Since the
setup is new, I can start from scratch so wish to nuke all the old info.
Mike
>
> 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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