upgrading a 2.2.12 murder to 2.3.14

[David Mayo]

Andrew Morgan wrote:

> On Thu, 16 Jul 2009, 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.
>>
>> 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?
> 
> Whatever you do, don't upgrade any of your frontends while you have older 
> backends.  The 2.3 code uses new IMAP calls that don't exist in 2.2. 
> Quoting myself from a couple years ago:
> 
>    I proceeded assuming I could have a v2.3.10 frontend with older v2.2.13
>    backends.  However, I was unable to get the APPEND command to work.
>    With telemetry logging enabled, I discovered that a 2.3 frontend issues
>    the IMAP command "Localappend" to a backend.  However, my v2.2.13
>    backend does not recognize "Localappend" as a valid command (and it is
>    not present in the source code).

We are in a very similar position to the Edinburgh guys except we have a 
single IMAP server running 2.2.12. Our plan was to set up our new 2.3.13 
back-end, use a 2.3.13 front-end, add the existing back-end to the new 
Murder, then transfer our mail using xfer.

Would it be more sensible to use a 2.2 front-end, move our mail to the 
new back-end and upgrade the front-end to 2.3? Presumably there is no 
"compatibility mode" for 2.3 that would make it issue only 
2.2-compatible commands? I'm surprised it can't work this out for itself.

Regards,


Dave.

David Mayo
Networks/Systems Administrator
University of Bath Computing Services, UK