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Re: [lvm-devel] Suppress locking initialisation failure messages when --ignorelockingfailure is used



On Mon, Feb 08 2010 at 10:31am -0500,
Milan Broz <mbroz redhat com> wrote:

> On 02/08/2010 04:09 PM, Mike Snitzer wrote:
> >>> Shouldn't rc.sysinit's "vgchange -a y --ignorelockingfailure" come
> >>> _after_ root's rw remount?
> >>
> >> Exactly. It should also start volume monitoring etc.
> >>
> >> Note that monitoring need rw access (at least for status log to syslog,
> >> but also if it triggers some change, it will require real lock - to perform
> >> repair, snapshot resize or other action; metadata backups etc).
> > 
> > The monitoring gets started, by the "lvm2-monitor" service, after
> > rc.sysinit.  So we should be fine there.
> 
> I was just not sure if "vgchange -a y" here tries to start monitoring or not.
> If so, what happens? (lvm2-monitor init rc skript then will just restart it?)
> Is it what we want?

Gah, good point!  Though with current rc.sysinit, because of read-only 
root, I believe monitoring will fail to start because of locking
failure.  But I can't clearly recall; will need to trace it.

Changing rc.sysinit's "vgchange -a y" to be after the root's remount rw
would effectively eliminate the need for the "lvm2-monitor" initscript
(for startup).  This could be a good thing.

But any removal of lvm2-monitor is secondary; as there is potentially
some value in having a script to start/stop monitoring.  Until it is
removed/disabled, at a minimum, we expose ourselves to redundant polling
at boot (e.g. snapshot-merge completion polling).  That is, IFF we move
rc.sysinit's "vgchange -a y" to be after remount rw.

I'm still not seeing a reason why LVM volumes are getting activated
before root's remount rw.  I think we should change that.  Then we're
left having to decide on LVM monitoring (disable that service?).

Mike


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