[Linux-cluster] is clvm a must all the time in a cluster ?

[Roger Peña]

--- Jonathan Brassow <jbrassow at redhat.com> wrote:

>  From the description, I am skeptical that clvm is
> your problem...   
> (Also, are you using a proper fencing mechanism?)
yes, fencing is ok
everytime the cluster lose contact with a node, it is
fenced very quickly :-)
but, in the cases I am describing, the nodes remains
members of the cluster so no need to fence anyone .
just happen that cman get stuck because some cman
service in some node get stuck, and because cman is
stuck we can't do anything that interact with cman
except with the node who make the problem (we have to
guess what node is :-) )
what I had found is that usually, clvmd is the one
that it is not working as it should, but in other
cases we just don't know who is causing the problem.
usually the reboot of the offending node provoque some
transicions in the cluster and cman get out of the
stuck and cluster come back to live :-)

the cluster is in production so I am very limited to
do tests.
right now the admin team agree into let clvmd work
(started at boot time) but if in the future we get
more problems and if we find that that problem somehow
is related with clvmd then we will try to revert the
cluster lvm setting from our SAN lv 
any downside with this approach except not be able to
run lvm commands ?

thanks
roger

> 
> We would probably need more information from the
> logs to determine  
> what is going on.
> 
>   brassow
> 
> On Feb 25, 2008, at 3:06 PM, Roger Peña wrote:
> 
> > Hi
> >
> > I am running RHEL4 with csgfs from centos, all
> > packages updates in both sets (RHEL and CS-GFS)
> > but since the last updates my cluster become more
> > unstable, sometimes after a failed shutdown of a
> > service (it failed because was unable to umount
> the
> > GFS) and the other two times just dont know
> exactly
> > why (I wasn't ther when it happen, just went to
> > fixed).
> > all of this in lest than two weeks
> > and every time, the cman infrastructure just hand
> or
> > collapse.
> > the first to times, I realice that one of the
> nodes
> > (and just one) was hanging the cman so the entire
> > cluster where in stand-by, until I fence (reboot)
> the
> > node.
> > from cman_tool services in that node, I guess clvm
> was
> > the guilty just because it were running (run
> state):-)
> > it shouldn't be in that state ;-) . it is just a
> > guess, ok? I am not an expert in CS.
> > also, a lot, and I mean a lot, of time my services
> > can't start is because the clustered LV are not
> > Activated even when clvm is running and cman_tool
> > services say it is running.
> > just a clvmd restar fix that.
> >
> > so, my question is, can I run the cluster with GFS
> > without clvmd working?
> > I don't have plans to work with lvm (extending for
> > example) the sistem is working and should be in
> the
> > same state (from the filesystem point of view) for
> a
> > long time.
> > so, can I "declusterice" the LV where GFS live?
> >
> > and if I can, what are the steps to do it?
> >
> > 1- vgchange -cn "VG Name"
> > 2- cmand stop
> > 3- lvmconf --disable-cluster
> >
> > I guess I don't need to unmount the LV to do that,
> do
> > I?
> > nore the data in those FS should be lost because
> of
> > that operation (tha change), right?
> >
> >
> > thanks in advance for the help
> >
> > cu
> > roger
> >
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