----- Original Message ----
> From: Stan Hoeppner <s...@hardwarefreak.com>
> To: postfix-users@postfix.org
> Sent: Mon, June 28, 2010 2:23:15 AM
> Subject: Re: performance tuning - relay
>
> Christian Purnomo put forth on 6/27/2010 5:50 PM:
> From your
> questions above, I could see where you're coming from that if
> Server2
> has performance problem then it would make sense to see the
> queue built
> up at Server1. I can confirm server2 is very underload at
> any
> time, the server is overspec'ed for what it is intended to do. I
>
> can also confirm while those thousands of emails queued up at Server1,
>
> Server2 was running smooth with 0.1-0.3 load average.
What
> piqued my curiosity is why the queue on server2 starting growing, and
rather
> large at that, _after_ you got the Postfix bottleneck straightened out
on
> server1.
> We have had server2 for about 4 years now and we have been
> having this
> issues in the last 1 year where one of our new server
> happens to be a
> mailling list which sends out thousands of emails to
> subscribers.
>
> Anyway, Server2 spec is HP DL385G4, 4G RAM, 6 SCSI
> disks RAID 5 and
> reiserfs.
I would have thought this
> hardware would be able to get the mails into the
mailboxen as quickly as
> server1 could push them over, without the queue
building up as you
> demonstrated in a previous message. Email service is
primarily a disk
> bound application. IIRC, with the DL385G4 you would have the
Smart
> Array 6i which is an integrated entry level controller. Even so,
> with
128MB of read/write cache and 6x10k(15?)rpm drives on a SCSI 320 bus,
> even in
a slowish RAID5 configuration, you should easily be able to sync to
> mailboxen
as many messages as server1 could push over either fast or gigabit
> ethernet.
This server should be able to sync a few hundred emails to disk per
> second.
Is the 6i just really horrible at RAID5, or is there something in the
> software
stack slowing things down? Were you peaking the disk subsystem
> when the queue
was building?
> The delivery method on Server2 is
> maildrop - we use some mailfilter rule
> to drop certain emails to certain
> folders. I can understand this is
> adding some overhead for the
> local delivery on Server2 but this is the
> cost I'm happy to take
> on. The queue can build up on Server2 and clear
> up overtime
> without impacting our primary MX (Server1).
I'm not familiar at all with
> maildrop as I've never used it. That said, I
wouldn't think maildrop
> alone would cause such a bottleneck. Some versions of
Reiser are known
> for great speed will lots of small files, at least as far as
delete
> performance. However, most versions of Reiser do not do so well
> with
large files. Reiser is normally a good performer with maildir, but
> doesn't do
so well with mbox, especially once the mbox files get
> large.
Other disk writes? Is maildrop or any other process you're
> running creating
extra log stamps per email processed? I assume you're
> storing the OS, logs,
mail, everything on that RAID5 volume. Is this
> correct?
As you stated, you're not really concerned with queue growth on
> server2. I
went through all this simply because I think you're leaving
> some performance,
maybe quite a bit, on the table WRT server2. I'm
> guessing it's in the
OS/software stack and not the hardware. You may be
> able to get this box
screaming with simple changes (reduce logging to only
> what's necessary), and
maybe one or two more major changes (maildir to mbox
> or vice versa, switching
from Reiser--defunct now anyway--to XFS). Or a
> really big change, dumping
Maildrop/Courier for Dovecot/LDA which is quite a
> bit quicker from everything
I've read. I say read because I've not used
> Courier but I have used Dovecot,
and still do.
Sorry if I've wasted
> your time here. I just thought I'd point out a few
things just in case
> you get the urge to poke around on server2 looking for a
little performance
> boost.
--
Stan
-----------------
Stan,
Actually you do not need to pay for their mail forwarding services. I have a
sever setup to accept email just fine and dandy for a dyndns.org support host,
and I do not pay anything for it. I get mail to my system woa.homeip.net just
fine without paying.
The paid for services you speak of are for people who want to customize their
own dyndns settings.
You can send me an email to crypto...@woa.homeip.net and I will receive it, and
I can send out. I would suggest you get a dyndns.org account, and do some
research on it.
I have been using dyndns.org since about 2001 when I first my DSL Connection.
Daniel Reinhardt
Website: www.cryptodan.com
Email: crypto...@yahoo.com
