[Lustre-discuss] Filesystem monitoring in Heartbeat

[Bernd Schubert]

On Thursday 21 January 2010, Adam Gandelman wrote:
> Jagga Soorma wrote:
> > Hi Guys,
> >
> > My MDT is setup with LVM and I was able to test failover based on the
> > Volume Group failing on my MDS (by unplugging both fibre cables).
> > However, for my OST's, I have created filesystems directly on the SAN
> > luns and when I unplug the fibre cables on my OSS, heartbeat does not
> > detect failure for the filesystem since it shows as mounted.  Is there
> > somehow we can trigger a failure based on multipath failing on the OSS?
> 
> Hi-
> 
> It would depend on the version of heartbeat you are using.  Heartbeat v1
> did not do any resource level monitoring and if that is what you are
> using you are out of luck.
> 
> If using v2 CRM and/or Pacemaker, you have two options:
> 
> 1, Modify the Filesystem OCF script's monitor operation to check the
> actual health of  the filesystem and/or multipath in addition to the
> status of the mount and return accordingly.   The Filesystem OCF agent
> is located at /usr/lib/ocf/resource.d/heartbeat/Filesystem
> 2, Create your own resource agent that interacts with dm/multipath to
> start/stop/monitor it.  Then constrain the resource to start before/stop
> after and run with the Filesystem resource.  Then the filesystem will be
> dependent on the health of the multipath resource.

I guess you want to use the pacemaker agent I posted into this bugzilla:

https://bugzilla.lustre.org/show_bug.cgi?id=20807

It does not interact with with multipath, but knows about several lustre 
details. 
How would you monitor multipath? If one of your several paths fails, what do 
you want to do? If all paths fail, it is clear, but what to for a partial path 
failure? I think think OCF defines a return code for that?
I also think mutipath should be a separate agent to reduce complicity from the 
script.


Cheers,
Bernd

-- 
Bernd Schubert
DataDirect Networks