What hardware to handle this

[Simon Matter]

>
>
> On Mon, 22 Nov 2004, Jim Bartus wrote:
>
>> I'm looking to redo our companys mailserver setup, and I want to move
>> from
>> our current system of POP3 to an IMAP based system.  I've done a fair
>> amount
>> of reading and Cyrus looks like the right answer, so I was hoping you
>> guys
>> could help me out with some final details.
>>
>> I have approx 500 users.  Of which probably only about 300 will be
>> connected
>> at peak times, but they will be consantly connected in the "check for
>> new
>> mail every 5 minutes" sense.  Overall the system will deliver about 25 -
>> 40,000 messages a day.  There will be a seperate SMTP server delivering
>> to
>> this via LMTP, and a seperate webmail server connecting in through IMAP.
>> Quota's will be set around 250MB and the use of sieve filters will be
>> enabled.  All with authenticate against our LDAP server (its not
>> purchased
>> yet, but it'll be novell edirectory).
>>
>> My major question is what kind of hardware will cyrus require to handle
>> that
>> level of load?  Currently we were planning on buying a dual 3.0GHz Xeon
>> system with 2GB of ram running RHEL 3.0.  For storage it'll connect via
>> HBA
>> to our EMC CX500 storage array.  Will that do it?  Does anyone have
>> anything
>> similar setup?
>
> Our setup is very similar to yours.  We have campus mail relays that
> handle all the MTA duties and deliver using LMTP to our Cyrus server.  The
> Cyrus servers is a Dell 2650 with two 2.8GHz cpus and 2GB of RAM.  It is
> attached to an external Dell 220S SCSI storage array, configured as RAID
> 0+1 (RAID 10).  Webmail (Horde/IMP) runs on separate boxes.
>
> We have about 25,000 active users/mailboxes and about 500 peak IMAP
> connections during the daytime.  Another poster mentioned bumping it up to
> 4GB, but I'm not sure that is necessary.  Here is the memory/cpu usage
> right now (about peak time) on our Cyrus server:
>
> Tasks: 545 total,   2 running, 543 sleeping,   0 stopped,   0 zombie
> Cpu(s):   8.6% user,   2.7% system,   0.0% nice,  88.7% idle
> Mem:   2068536k total,  2055052k used,    13484k free,    53252k buffers
> Swap:  2000084k total,    18492k used,  1981592k free,   970056k cached
>
> The system uptime is just over 100 days, so I'd say that it rarely uses
> swap.

I agree on that. On one of our servers we have ~1700 users with ~600
concurrent IMAP users during daytime, the quotas are all 1G and more. It's
a DELL 46xx with dual 2.8GHz Xeons and 8G of ram (it was one of those
double your memory for free offers). Unfortunately the additional memory
seems almost useless in our situation, this is what free reports after 91
days of uptime:

[root at xxx root]# free
             total       used       free     shared    buffers     cached
Mem:       7933920    7742620     191300          0     210200    7036380
-/+ buffers/cache:     496040    7437880
Swap:      9775544     538432    9237112

The real bottleneck in our case is disk IO. We have plenty of U160 disks
connected to the onboard Raid controller giving us ~1Tb in a Raid5
configuration with weak performance.

Simon


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