online moving mailbox to a different partition

[Bron Gondwana]

On Mon, Oct 31, 2011 at 01:58:01PM -0700, Andrew Morgan wrote:
> On Mon, 31 Oct 2011, Martin Kraus wrote:
> 
> > hi. I have several hundred gigs of mail messages on a partition and I'd 
> > like to move it to a different partition but copying takes a very long 
> > time and I don't want to have such a long downtime. I was wondering if 
> > the renamemailbox command moves a whole mailbox to a different cyrus 
> > partition online including the whole mailbox hierarchy?
> 
> If I remember correctly, Cyrus will lock the mailbox while it moves it.  I 
> try to do mailbox moves during low usage times, but I don't bother 
> scheduling an outage for it.  I've never had any users complain.

Honestly, replication is much nicer than anything else for this!  I
wonder if we could use the replication engine to do partition moves
locally.  Basically, it does three passes - so the final moment in
which the lock is required is very short - there is very little data
to transfer, and all the files required are hot in cache.

For a rename within a single filesystem there's less clear value in
the idea - you're bargaining on the links taking a long enough time
to justify the multiple rewrites of the cyrus.index rather than
just copying the files over.

Bron.