Cyrus v2.2 and v2.3 interoperability

[Andrew Morgan]

On Tue, 1 Sep 2009, Eli Ben-Shoshan wrote:

> We here at the University of Florida are running a good sized cyrus murder
> setup. We have 10 cyrus v.2.2.12 backends with 9 cyrus v2.2.12 frontends and a
> dedicated mupdate master running v2.2.12.
>
> We are now in the planning phase of moving to the cyrus v2.3 branch. We will be
> installing all v.2.3.7 nodes since that is what is the latest available in RHEL 5.3.
>
> We would like to upgrade just the frontends and mupdate first since we are
> redesigning our backend's storage infrastructure. Later on we plan on upgrading
> the backends to v2.3 with replication.
>
> Can this be done?
> Is it safe to run v2.3 frontends and mupdate while keeping v.2.2 backends?
> Should we leave mupdate at v2.2 and upgrade just the frontends to v2.3?
> Are there specific versions of cyrus to avoid in this situation?
> Has anyone actually done this before?
>
> Any insights are welcomed. Thanks in advance.

Sorry, you must upgrade all of your backends before your frontends.  2.3 
frontends try to issue an IMAP command to the backends that 2.2 doesn't 
understand.

Quoting myself back in 2007:

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).


I'm not aware of any version requirements or problems for the mupdate 
master.  I would probably upgrade in this order: mupdate > backends > 
frontends.

 	Andy