[cgl_discussion] [Fwd: [ogfs-dev]EVMS 2.0 with cluster support]

Joe DiMartino joe at osdl.org
Wed Apr 2 16:12:13 PST 2003

On Wed, 2003-04-02 at 15:22, Ram Pai wrote:
> On Wed, 2 Apr 2003, Peter Badovinatz wrote:
> > John Cherry wrote:
> > >
> > > EVMS has been released as a clustered volume manager.  It could address
> > > things like cluster wide device naming and could replace the notion of
> > > pools in OpenGFS.  Does anybody on the cgl_discussion list have some
> > > bandwidth to evaluate this?
> We support cluster wide **volume** device naming. What this means is
> that EVMS volumes created on Shared containers will show up as a
> volume device with the same name on all cluster nodes.

Yes, this is adequate for a pool replacement.  OpenGFS assumes that the
mounted device name is the same for each filesystem, and only the volume
level will be mounted.

> And from the discussion with the OpenGFS folks today, I understand
> that this is what they want.

It seems that EVMS has met the requirements as stated so far.

> Pools can be replaced with EVMS volume devices residing on shared container.
> However we do not have an equivalent of a sub-pool.

Sub-pools are simply a partitioning scheme where a logical device can be
broken into smaller logical devices.  It seems that EVMS can simply make
more volumes out of the same space and get the same result.

> We are eager to receive feedback, and requirements that drives our future
> development.
> Thanks,

As we discussed today in the OpenGFS meeting, the next step is to write
some plug-in code and test it.  Ben Cahill is currently removing a
dependency that requires external journals to need the pool driver.  I
don't know how extensive that might be, but it's most likely ioctl calls
to the pool driver.

-- Joe DiMartino <joe at osdl.org>

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