[Lustre-discuss] questions about an OST content

[Ashley Pittman]

On 6 Nov 2010, at 19:28, Bob Ball wrote:
> I intend to be VERY careful with this.  Thank you all.  Any further 
> advice before I do this, likely on Monday, will be greatly appreciated.

I believe it is possible to use udev to assign device names to devices which would make the pathname both consistent across boots and configurable.  If it isn't possible with udev then I know it's possible with multipath as we always use this on DDN systems (I work for DDN), it both handles failover between devices but also allows them to be named as we choose.  I'm not saying we're not careful ourselves but you need to be a lot less careful if you are working with /dev/mapper/ost_24 than you do if you are working with /dev/sdj

Basically install device-mapper-multipath and add the entries to /etc/multipath.conf.

On one of our test systems in the lab we have the following currently, this is a virtual test system so only single path to each device.

/dev/mapper/ost_sab_1
                       4128448   1579584   2339152  41% /lustre/sab/ost_1
/dev/mapper/ost_sab_0
                       4128448   1278200   2640536  33% /lustre/sab/ost_0

Ashley.

-- 

Ashley Pittman, Bath, UK.

Padb - A parallel job inspection tool for cluster computing
http://padb.pittman.org.uk