On 1/17/11 7:18 AM, Jaques Cochet wrote:
If postfix alone is running on the server, let's say as a mail router
or backend delivey system, would postfix processes make use of all
cores?
That's a loaded question, since "postfix" is not a process that consumes
CPU.
In one (1) postfix instance, there is exactly one process that is
limited to one thread: the queue manager qmgr(8).
All other processes except master(8) - which doesn't use all that much -
are started as needed, as many times as you configure them to.
Since every single message that is considered for delivery will pass at
least once through the queue manager, that is your real, CPU-bound
performance ceiling.
As has already been explained, disk I/O on the queues will become your
bottleneck a long time before the qmgr gets in trouble - a very long time.
would I be left with cores doing nothing even If I have an
important number of emails to process?
On Mon, Jan 17, 2011 at 7:02 AM, Victor Duchovni
<victor.ducho...@morganstanley.com> wrote:
On Mon, Jan 17, 2011 at 06:55:39AM +0200, Jaques Cochet wrote:
Does increasing the number of cores on the same hardware platform add
performance to a Postfix system or it is better to run several Postfix
systems on different machines?
Yes, but only if the CPU is the bottleneck. Typically this happens when
you use CPU-intensive Anti-Virus or Anti-Spam content filters or milters.
Multiple messages will be scanned in parallel, and additional concurrency
will help, provided the disk or network is not bottleneck.
If the second choice is better, is it
logical to run Postfix on different VMs (using ESX for example),
let's say on something like 12 cores?
VMs will just make your life worse. Only needed if you need different
O/S versions for the various software components, but be prepared for
pain with timing and subtle resource allocation issues.
I will use Postfix for email
scanning (using Mail scanner) and relay and also for mail delivery.
Don't use "Mailscanner". There are other A/V scanners out there that
are not incompatible with Postfix, Mailscanner is not one of them,
unless its architecture has substantially changed recently.
--
Viktor.
--
J.
