Re: [dm-devel] multipath failover with 2x Emulex LP9802, setup, WWIDs

[Andreas Huck <dm-devel huck it>]

Hi,

On Thursday 25 November 2004 10:29, Lars Marowsky-Bree wrote:
> On 2004-11-25T08:55:09, Andreas Huck <dm-devel huck it> wrote:
> 
> > First, how to get a WWID?  I have 4 devices with 2 paths each.
> > `scsidev -s` should provide it but doesn't:
> > 
> > # scsidev -s
> > Serial number of /dev/scsi/sgh1-1c0i0l3: "0003cc7420000080e512cc740000000000000000"
> > Serial number of /dev/scsi/sdh1-0c0i0l3: "0003cc7420000080e512cc740000000000000000"
> >  HSV OS Id: 0
> > Serial number of /dev/scsi/sgh1-1c0i0l2: "0002cc7420000080e512cc740000000000000000"
> > Serial number of /dev/scsi/sdh1-0c0i0l2: "0002cc7420000080e512cc740000000000000000"
> >  HSV OS Id: 0
> > Serial number of /dev/scsi/sgh1-1c0i0l1: "0001cc7420000080e512cc740000000000000000"
> > Serial number of /dev/scsi/sdh1-0c0i0l1: "0001cc7420000080e512cc740000000000000000"
> >  HSV OS Id: 0
> > Serial number of /dev/scsi/sgh1-1c0i0l0: "0000cc7420000080e512cc740000000000000000"
> > Serial number of /dev/scsi/sdh1-0c0i0l0: "0000cc7420000080e512cc740000000000000000"
> >  HSV OS Id: 0
> > Serial number of /dev/scsi/sgh0-0c0i0l3: "0003cc7420000080e512cc740000000000000000"
> > Serial number of /dev/scsi/sdh0-0c0i0l3: "0003cc7420000080e512cc740000000000000000"
> >  HSV OS Id: 0
> > Serial number of /dev/scsi/sgh0-0c0i0l2: "0002cc7420000080e512cc740000000000000000"
> > Serial number of /dev/scsi/sdh0-0c0i0l2: "0002cc7420000080e512cc740000000000000000"
> >  HSV OS Id: 0
> > Serial number of /dev/scsi/sgh0-0c0i0l1: "0001cc7420000080e512cc740000000000000000"
> > Serial number of /dev/scsi/sdh0-0c0i0l1: "0001cc7420000080e512cc740000000000000000"
> >  HSV OS Id: 0
> > Serial number of /dev/scsi/sgh0-0c0i0l0: "0000cc7420000080e512cc740000000000000000"
> > Serial number of /dev/scsi/sdh0-0c0i0l0: "0000cc7420000080e512cc740000000000000000"
> >  HSV OS Id: 0
> 
> There are 4 distinct WWIDs in there; I fail to see your problem?

I was always wondering why my favorite distribution shows 
"Searching for braille display..." at boot-up. I guess I need
to rewrite my Xmas wish list... ;-)

> 
> This should work mostly out of the box.
yep, worked. But - grep is my friend - there is only a dmsetup command
in the evms init script which I don't use, of course. At system startup I
need to do the following:
 
fsrv1:~ # for i in `seq 1 3`; do dmsetup create lun$i dmtable.lun$i; done

Where is the usual place to put this? Or could multipathd care for this dmsetup? 

This for the reference:

fsrv1:~ # dmsetup ls
lun3    (253, 2)
lun2    (253, 1)
lun1    (253, 0)

fsrv1:~ # for i in dmtable.lun*; do echo "$i: `cat $i`; done
dmtable.lun0: 0  274968576 multipath 2 round-robin 1 0 /dev/sdb round-robin 1 0 /dev/sdf
dmtable.lun1: 0 1374986240 multipath 2 round-robin 1 0 /dev/sdc round-robin 1 0 /dev/sdg 
dmtable.lun2: 0 1374986240 multipath 2 round-robin 1 0 /dev/sdd round-robin 1 0 /dev/sdh

> 
> > I tried a direct approach by dmsetup, but didn't get a device:
> > 
> > # echo "0 274968576 multipath 10 2 1 round-robin 1 0 \
> > /dev/sdb 1 round-robin 1 0 /dev/sdf" | dmsetup create /dev/dm-0
> > k_set_name: Device /dev/dm-0 not found
> > Command failed
> 
> This is the wrong syntax for dmsetup; you need to give a table name.
> "dmsetup create whatever" would create the appropriate table.
> 
> > # /sbin/devmap_name 8 16
> > No devices found
> 
> No wonder, there's no device map for 8:16, it's a SCSI device.
OK, you are right. There are other fruits than apples...

> 
> > Do I overlook something important here?
> 
> Yes. Try reading the documentation again ;-)
Well, I may write some additions to fill the gaps I stumbled accross.

Regards,
Andreas Huck

> 
> 
> Sincerely,
>     Lars Marowsky-Brée <lmb suse de>
>