[gpfsug-discuss] Device mapper

[Loic Tortay]

On 10/04/2018 00:51, Nick Savva wrote:
> Hi all,
> 
> Apologies in advance if this has been covered already in discussions.
> 
> I'm building a new spectrum scale cluster and I am trying to get consistent device names across all nodes. I am attempting to use aliases in the multipath.conf which actually works and creates the /dev/mapper/<disk name> link.
> 
> I understand you can also copy the bindings file but I think aliases is probably easier to maintain.
> 
> However Spectrum scale will not accept the /dev/mapper device it only looks for dm-X devices that are in the /proc/partitions file. I know SONAS is pointing to Device mapper so there must be a way?
> 
> Im looking at the /var/mmfs/etc/nsddevices is it a case of editing this file to find the /dev/mapper device?
> 
Hello,
We're doing this, indeed, using the "nsddevices" script.

The names printed by the script must be relative to "/dev".
Our script contains the following (our multipath aliases are "nsdXY"):
  cd /dev && for nsd in mapper/nsd* ; do
          [ -e $nsd ] && echo "$nsd dmm"
  done

  return 0

The meaning of "dmm" is described in "/usr/lpp/mmfs/bin/mmdevdiscover".


Loïc.
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|   Loïc Tortay <tortay at cc.in2p3.fr>  -     IN2P3 Computing Centre     |