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Re: performance tuning - relay

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  • Daniel V. Reinhardt
    ... What ... rather ... on ... I would have thought ... mailboxen as ... building ... primarily a disk ... Smart ... 128MB of read/write cache and ... a
    Message 1 of 10 , Jun 28, 2010
      ----- Original Message ----
      > From: Daniel V. Reinhardt <cryptodan@...>
      > To: postfix-users@...
      > Sent: Mon, June 28, 2010 3:32:04 AM
      > Subject: Re: performance tuning - relay

      ----- Original Message ----
      > From: Stan Hoeppner <
      > ymailto="mailto:stan@..."
      > href="mailto:stan@...">stan@...>
      > To:
      > href="mailto:postfix-users@...">postfix-users@...
      > 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.

      > piqued my curiosity is why the queue on server2 starting growing,
      > and
      > large at that, _after_ you got the Postfix bottleneck
      > straightened out
      > 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
      > up as you
      > demonstrated in a previous message. Email service
      > is
      primarily a disk
      > bound application. IIRC, with the DL385G4
      > you would have the
      > 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
      > 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
      > are known
      > for great speed will lots of small files, at least as far
      > as
      > 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
      > 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.

      > 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.




      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
      > ymailto="mailto:cryptodan@..."
      > href="mailto:cryptodan@...">cryptodan@... 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.

      > Reinhardt
      Website: www.cryptodan.com
      > ymailto="mailto:cryptodan@..."
      > href="mailto:cryptodan@...">cryptodan@...


      Please disregard my reply to this message thread. I was going to reply to another thread, but had this one highlighted. Sorry for butting in.

      Daniel Reinhardt
      Website: www.cryptodan.com
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