Cyrus and scale-out

Sebastian Hagedorn Hagedorn at
Fri Jun 10 11:18:12 EDT 2016


our systems guys keep telling us that we are doing things in an 
old-fashioned way and should get with the program.

We are currently using a single Cyrus server with roughly 13 TB of storage 
provided by a SAN. We used to have a Red Hat High Availability cluster, but 
we traded that in for a VMWare HA setup earlier this year. So far we have 
scaled up. We have added processors, RAM and storage to that single 
(virtual) machine whenever necessary.

According to our systems people, we should scale out instead, the way 
Exchange 2013 and Dovecot Pro apparently do. The idea, as I understand it, 
is to have multiple backends that all provide access to the same mailboxes. 
It should be possible to add and remove backends completely transparently. 
Dovecot Pro seems to realize that by storing all mails in local caches 
backed by shared object storage (e.g. Ceph), in conjunction with Dovecot 

Now I'm trying to understand if anything like that is on the roadmap for 
Cyrus. I see that Cyrus 3.0 (experimentally) supports object storage, but 
only for archive partitions. Are there plans for Cyrus 3.1 or later to add 
support for regular mail partitions as well?

Personally I'm stil happy with our setup, but I'm told that future storage 
hardware won't easily support what we're doing anymore. I'm aware that both 
clustering and replication are already possible with Cyrus, but my 
understanding is that you can't trivially and automatically switch to a 
replicated backend if one goes down. You also need to replicate all 
messages to each new backend you introduce, which isn't quite what our 
systems people would like to have.

    .:.Sebastian Hagedorn - Weyertal 121 (Gebäude 133), Zimmer 2.02.:.
                 .:.Regionales Rechenzentrum (RRZK).:.
   .:.Universität zu Köln / Cologne University - ✆ +49-221-470-89578.:.
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