Recommend how to move 31GB of mail to a new server

[Alain Williams]

On Sun, Jun 24, 2007 at 10:50:28AM +0200, Ulrich Spoerlein wrote:
> On Sat, 23.06.2007 at 22:34:33 -0300, Patrick Boutilier wrote:
> > Daniel O'Connor wrote:
> > > On Sunday 24 June 2007 07:37, Gary Mills wrote:
> > >> For only 30 gigabytes, you might be better off just copying the files
> > >> over, with IMAP down.  It could only take a few hours.  You can copy
> > >> a sample from the live system to get an idea of the timing.
> > > 
> > > You could rsync the mail spool while it is live, take it down and then 
> > > rsync again.
> > > 
> > > That should save considerable time as I would imagine the vast majority 
> > > of email would be unchanged between the first & second copy.
> > 
> > But unfortunately rsync will still have to scan each file to determine 
> > what has changed, and that can chew up a lot of time.
> 
> Better than to speculate is to measure.
> Time the rsync of the mailboxes to your new server. *Don't* shutdown
> cyrus, but rsync right again. Measure the second run, too. This will
> roughly be your expected downtime. I would be surprised if it is more
> than 5-10 minutes.
> 
> You could also do: rsync (long time), rsync (short time), shutdown
> cyrus, rsync (even shorter time).

I did this a couple of years ago with some 250GB mail. Machines physically close,
so good connectivity, but 250GB still takes forever. I ran rsync over a few nights,
just killing it at 8am. This got us close to where we wanted to be, then on a Saturday
I took everything down and ran a final rsync that, IIRC, took about 1/2 hour; switched
cyrus/mail/... on the new server on and voila - migration completed.

-- 
Alain Williams
Linux Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer.
+44 (0) 787 668 0256  http://www.phcomp.co.uk/
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