On 2009, Aug 18, at 13:32, Ski Kacoroski wrote:
> At $work we purchased a new mail server (Scalix) and need to migrate
> from our old mail server (CommunigatePro). We have 2500 accounts with
> the largest account about 4.2GB/53000 messages. Our problem is that
> in
> testing several of the imap migration programs available (mailutil,
> imapsync, MoveIMAPMail) we are looking at roughly 30 days to complete
> the migration which just is not going to work. One idea we have for
> doing this in a weekend is to have 30 processes running in parallel,
> but
> I am wondering what other people do to migrate to a new mail server
> in a
> large organization.
What I've done in the past when migrating a bit more that that, even,
was simply: rsync.
Granted, I was using mail servers that made that a reasonable thing to
do: MessagingDirect to Sendmail in one instance and merely from one
system to another using the the server from whence both of those came:
Cyrus. What made it easy to do with those is that they use individual
files on a per message basis and all shared the same storage format.
The largest of my copies/moves used a multi-stage directory hashing,
and I did find it much faster to kick off an rsync on each top-level
hash directory rather than doing it on the top-most enclosing
directory. [I.e., a dozen rsync processes rather than just one.] In
particular, doing it that way allowed me to copy everything several
times over the days leading up to the big conversion, then when time
shut down the services and do a final update copy/delete.
If the structure of your mail server allows you to do that, your total
down-time can be really minimal.
Unfortunately, though, you are moving from/to different products that
do not share storage formats on the disk, so rsync is likely out of
the question for you.
A quick check on Scalix's site (to see if their storage format was
obvious) shows that they actually recommend using the imapsync tool,
but the biggest problem with that is that the password for the user
needs to be known since I don't know if there is a mechanism by which
either server would allow you to authenticate as some administrative
account that would then be able to access and manipulate users folder
hierarchies.
A big thing to consider is whether you will be planning on one big
light-switch cut-over keeping the service name the same to refer to
the server regardless which server application you're running or
whether you have the option of doing a transition mechanism by which
you could set up something like one of:
new server on new/temporary name to allow users to check it out and
move their own mail with a change of names (and where incoming mail is
delivered) "later", or
new server into production with the old one available for access to
the older mail allowing them to move their own e-mail in some way
just using a different name for the new server
With any of those, you might consider something like making a web-
enabled way of invoking Scalix's recommended imapsync to assist the
users with moving their e-mail. Using an imapsync mechanism, since it
just does the fetch and imap put, can be done at any time since the
imap server will be maintaining the proper mailbox structure and
conflicts really are not a concern.
Those might even trigger thoughts of a few other ways, depending on
your needs for your users, but that's what comes to mind off the top
of my head.
-philip
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