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Re: Mail server

Russell Coker wrote:
> On Mon, 24 Feb 2003 18:34, Colin Ellis wrote:
> > Email doesn't really need much processing, but does take 
> > surprisingly large amounts of disk space.
> Obviously such things differ depending on exactly who is 
> using the service and what they are doing.
> But my experience is that with modern disks a mail server 
> will run out of seek 
> performance before it runs out of space.
> [...]
> If a message delivery takes 10 disk writes (actually it 
> probably takes more 
> once you count writing to two files in the queue then writing 
> it to the spool 
> and deleting the queue files with lots of fsync() along the 
> way) then such a 
> machine can only deliver 13 messages per second.
> I have been considering modifying the Qmail and maildrop code 
> to not use 
> fsync() etc to allow more users per server (yes I know about 
> the reliability 
> issues, but there are lots of more important things to worry about).

Well, qmail is an I/O hog. We have a (small) list-server at a customer which
was set up with qmail (w/ el-cheapo 20 GB IDE HDDs). Could only send at ~512
kbit. Then replaced qmail with postfix, now it saturates the customer's T1
without problems...

>From my experience, you should use a hardware raid controller w/ (at least)
10000 UPM SCSI disks, and postfix+courier imap. CPU power should be no
problem, it's seek I/O that matters.

Just my 0.02 Euros

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