A beginner question about Murder

Michel Sébastien Sebastien.Michel at atosorigin.com
Mon Sep 20 04:23:54 EDT 2010

>> So we use about ten common Intel based servers for BEs (sized to
>> support loss of 2/3 servers) and store data on NAS. Users are active
>> and filer is about tens of thousand nfsop/s at the busy hour.
>> About 10% to 20% of the users connect at least one time a day, globally
>> 4 million connections per day.

> These are quite massive figures -- I'm thoroughly impressed. I am
> assuming that your back-ends experience 50,000-100,000 concurrent IMAP
> connections during certain parts of the day. This means that each BE
> takes 5,000-10,000 parallel connections. Can an ordinary Intel server
> handle such loads? What's the CPU and RAM of each?

We don't have to handle such load. Most of end-users connect on pop3d (we provide a pop3 optimizer to reduce I/O, see http://www.mail-archive.com/cyrus-devel@lists.andrew.cmu.edu/msg01194.html) , others connect on the webmail (our webmail uses disconnected imapd sessions and is optimized thanks to Cyrus statuscache db).

> Also, how many NAS servers/appliances are being used? I would have
> thought that something like NFS would be too slow for such heavy IO
> loads, but evidently I'm wrong.

One huge is enough and cheaper than a SAN. Also we have very experienced system admins to tune the filer !

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