Hi,
we use a modified "traditional" murder, i.e. without murder daemon, to host 
more than 2 million mailboxes (dozen million entries in mboxlist with folders)

We started to host 200.000 mailboxes on the "traditional" murder, configured 
with berkeley as cyrusdb backend due to lot of corruptions with default 
skiplist format (cyrus 2.3.9).
However we had a lot of locks and contentions with berkeleydb, so we migrated 
later to cyrus 2.3.13 on a skiplist backend. Unfortunately the more we hosted 
mailboxes the more we had production issues. Indeed database resync is not 
incremental and servers restart were increasingly longer. Moreover we had 
instability with skiplist backend around 7.8 million entries and failed to 
reach 8 million entries.

Finally we chose to develop a customized mysql backend. Front-ends and 
back-ends are all connected to the same DB but SQL results are rewritten with 
plugins to make them happy (return mailbox type 1 for proxy en mailbox type 0 
for backend). Now there is no more latency or issue and mysql allows us to host 
more several dozens million of entries.

So, we are totally murderless. FEs are scalable thanks to mysql replication and 
BEs are almost high available (our mysql failover is read-only and don't permit 
acl or folder management, but it is acceptable for us).
We developed our owns mysql backend and we can share the source code if someone 
is interested (perhaps need some clean-up and code rewrite to adapt to the 
"official" sql backend)

Sébastien

-----Message d'origine-----
De : info-cyrus-bounces+sebastien.michel=atosorigin....@lists.andrew.cmu.edu 
[mailto:info-cyrus-bounces+sebastien.michel=atosorigin....@lists.andrew.cmu.edu]
 De la part de Wesley Craig
Envoyé : jeudi 9 septembre 2010 20:16
À : Andrew Morgan
Cc : Shuvam Misra; info-cyrus@lists.andrew.cmu.edu
Objet : Re: A beginner question about Murder

On 08 Sep 2010, at 16:41, Andrew Morgan wrote:
> Unfortunately, I've never setup a "unified" Murder, so I don't fully
> understand what the advantages and disadvantages of it compared to a
> "traditional" Murder.  Maybe someone else can jump in here with their
> experiences.

The main advantage is that BEs can proxy for other BEs, no FEs are required.  
In m observation, the FEs are typically CPU bound, while the BEs are typically 
IO bound.  Since the BEs have an excess of CPU, it makes some sense to combine 
the two roles.

Other than the bugs one finds in new code, unified is logically superior to 
"traditional" and in the long run traditional should be retired.

In the future, I'd like to add "unified" replication, masterless murder, and 
auto failover. In my ideal minimum system, there are two machines, replicating 
to each other, providing high availability, proxying, etc.

:wes
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