[Lustre-discuss] Lustre on mpath devices

[Andreas Dilger]

On Oct 24, 2007  17:49 -0700, Klaus Steden wrote:
> Does an FS label (i.e. LUSTRE-OST0001) provide the same functionality as the
> consistent device name that the multipath device-mapper provides?

That depends...  It depends on what "blkid -t LABEL={fsname}-OST0001"
returns.  It _should_ be smart enough to return the DM device, but
it is prudent to make sure of this.  There shouldn't be any problem
with mounting the Lustre filesystems by LABEL= (which is one reason we
moved to a mount-based setup).

> On 10/24/07 5:43 PM, "Klaus Steden" <klaus.steden at thomson.net>did etch on
> stone tablets:
> > Does a multipathed setup automatically address failover, or is STONITH
> > configuration still required to automatically remap devices normally served
> > by downed servers?

No, multipath doesn't help failover at all, it only prevents device access
problems for the one node accessing the OST filesystem.

> > On 10/24/07 4:09 PM, "Cliff White" <Cliff.White at Sun.COM>did etch on stone
> > tablets:
> > 
> >> Klaus Steden wrote:
> >>> Does device multi-pathing have to be configured before the file system has
> >>> been created?
> >>> 
> >> Lustre needs a consistent device name, so I would say yes.
> >> 
> >>> Is there any documentation I should be referring to on the Lustre side to
> >>> get this set up?
> >> 
> >> No, as long as you give Lustre something that looks like a block device
> >> it's fine. There is no special setup for multipath devices. Which is why
> >> the consistent device name is important.
> >> 
> >> cliffw
> >> 
> >>> 
> >>> thanks,
> >>> Klaus
> >>> 
> >>>> On Oct 23, 2007, at 3:54 AM, Marco wrote:
> >>>> 
> >>>>> Hello,
> >>>>> 
> >>>>> I am new to this list and Lustre, please excuse me if I am asking an
> >>>>> already-answered question (I searched the archives without success).
> >>>>> 
> >>>>> I'd like to use Lustre on a cluster where MGS/MDT and OSTs hosts can
> >>>>> access some logical volumes (one for each host) exported from a SAN
> >>>>> through fiber channel links, and available under /dev/mapper/mpathN.
> >>>>> 
> >>>>> Is this configuration possible? Are there any known issues with it?
> >>>>> 
> >>>>> 
> >>>>> Thanks in advance
> >>>>> Regards
> >>>>> 
> >>>>> -- 
> >>>>> http://digilander.libero.it/mabozzo/
> >>>>> 
> >>>>> _______________________________________________
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> >>> 
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> > 
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Cheers, Andreas
--
Andreas Dilger
Sr. Software Engineer, Lustre Group
Sun Microsystems of Canada, Inc.