upgrading a 2.2.12 murder to 2.3.14

[Dave McMurtrie]

Gavin Gray wrote:
> We are planning towards upgrading our existing murder. The murder has  
> four front ends, three backends and separate mupdate and lmtp servers.  
> We want to move from version 2.2.12 to 2.3.14 so that we can make use  
> of delayed expunge an possible replication.
> 
> We have several thousand users currently having 4 TB of mail.
> 
> Any comments on the following would be welcome:
> 
> 1. We plan to gradually migrate users from the existing backend  
> machines to new backend servers running 2.3.14 that have been  
> integrated into our murder. We plan to do this using xfer. Although  
> this is very time consuming we are under the impression that cyrus  
> recommends using imap itself to do migrations rather than trying   
> underlying filesystem copies of some kind.
> 

That sounds fine.

> 2. We should end up then with our existing murder but with three  
> backends running 2.3.14. We then plan to upgrade the other machines in  
> the murder to 2.3.14 in the following order: frontends then lmtp and  
> finally the mupdate server. Does this make sense?
>

I can't think of anything that would make the order matter, so this also 
is fine.


> 3. As part of our preparation for this work we have been experimenting  
> with cyrus replication. The replication protocol seems pretty solid,  
> however we have some concerns about how to make use of it in our  
> upgrade. We are considering having a replicant machine for each of the  
> new backends. But this makes the migration even slower. In our tests,  
> if we migrate users via xfer to a machine that is doing rolling  
> replication, the replication takes around three times as long to  
> complete as the xfer. Does anyone have any experience of migrating to  
> a replicating environment?

Perhaps consider treating the migration and replication as two separate 
things.  It's not that you have to for technical reasons, but it will 
probably make your life less complicated.  Nothing stops you from 
enabling replication once you're all done with the upgrade.

Thanks,

Dave
-- 
Dave McMurtrie, SPE
Email Systems Team Leader
Carnegie Mellon University,
Computing Services