[Linux-cluster] GFS2 vs EXT3+HA-LVM

Corey Kovacs corey.kovacs at gmail.com
Tue Sep 29 20:04:38 UTC 2009


Rafael,

Thanks for the reply.  So far the set up is behaving as promised for me
although I've not tried to create any new volumes since the last time I
reboted so I'll mark that one for day after tomorrow when I am back at work.
Could very well be that I have it all wrong with respect to locking_type=1.
Actually reading the docs a bit closer indicates that you are right. I'll
check still

Thanks


-Corey





On Tue, Sep 29, 2009 at 8:21 PM, Rafael Micó Miranda
<rmicmirregs at gmail.com>wrote:

> Hi Corey,
>
> El dom, 27-09-2009 a las 01:48 +0100, Corey Kovacs escribió:
> > clvmd is still used, basically it just makes sure the lvm changes are
> > propagated to all nodes. The change is in the /etc/lvm/lvm.conf where
> > locking_type=1 instead of 3 as is for GFS1/2. If I go this route,
> > there will be no use of GFS at all on this cluster. locking_type=1
> > along with the volume_list config options are used to ensure that no
> > two nodes have the same VG mounted.
> >
> > Of course this method is new to me so my understanding of how lvm2
> > works with locking_type set to one works in conjunction with clvmd
> > running could be incorrect.
> >
> > As always, comments are appreciated.
> >
> > Corey
> >
>
> >
> >
> > --
> > Linux-cluster mailing list
> > Linux-cluster at redhat.com
> > https://www.redhat.com/mailman/listinfo/linux-cluster
>
> First, sorry for being late. I marked it as a "to read" topic, but i did
> not read it until now.
>
> >From your interest in EXT3+HA-LVM configuration, I understand you need a
> high-availability solution for your service, but you don't need
> concurrent access to the filesystem.
>
> I found the same problems as you on GFS2 performance, being far away
> from the results made by EXT3. I have also tested XFS filesystems in
> this situations with even better performance (and now in RHEL 5.4 XFS
> filesystem is introduced as an Technological Preview, so we can expect
> it to be ready for mission critical usage in 5.5 or so).
>
> I studied the HA-LVM solution but i found it "ugly" in terms of
> administration. Then i chose the CLVM and tried to find a way to
> guarantee access to volumes only by one node in the cluster, avoiding
> administrator mistakes and mountings of non-clustered filesystems in
> more than one node at the same time.
>
> There was an "undesired behaviour" in the LVM "exclusive" flag, which
> Brem submitted to the bugzilla (thanks again). If fixed, I hope a
> RGMANAGER resource script I submitted could be into the project to
> implement this LVM "exclusive" usage.
>
> If you don't need the access to storage in a high availability solution
> (handled by a cluster software) i encourage you to check this LVM
> "exclusive" option by hand, without integrating it into RGMANAGER. For
> testing purposes it should be ok. I will also recommend you to try XFS
> filesystem on top of it. I can give you some instructions if you need.
>
> If you need the access to storage in a high availability solution, you
> should try the LVM resources included in RGMANAGER. Also try with XFS on
> top of it.
>
> About the "locking_type = 1" into CLVM issue: i did not even think that
> it would be possible to use it. I would expect CLVM not propagatingRafael
> changes if set to 1. Have you done any tests about this? Is the
> configuration working as you expected?
>
> Cheers,
>
> Rafael
>
> --
> Rafael Micó Miranda
>
> --
> Linux-cluster mailing list
> Linux-cluster at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-cluster
>
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