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Subject: RE: Some questions on postfix, SUMMARY
From: Brad Knowles (blkskynet.be)
Date: Fri Mar 03 2000 - 16:58:36 CST

At 2:30 PM -0500 2000/3/3, Karimov, Rashid (NBC, CNBC) wrote:

> As long as format of the message is not OS and/or HW
> specific(byte order for example),it wouldn't be a problem ?
> Say, if a message file is generated on Windoze NT box, and then copied
> into maildrop box on Unix, will it be delivered ?

        You seem to be permanently stuck on this concept of generating a
queue file somewhere, and then trying to quickly push it off
somewhere else. Why is this?

        If you want something that is 100% totally independant of OS, and
is likely to make the absolutely maximum highest throughput possible
with postfix, then use SMTP. You've already been told this, several
times. You've even been told that Wietse would give you a program
that should implement the minimal SMTP protocol as quickly as
possible, and this could should be fairly portable to any OS you like.

        Connect over a Unix socket, or via a TCP socket, whatever you
want. Make sure that you turn off all checking (you should ensure
valid e-mail addresses, etc... out of the database) on this postfix
server, but have it forward all it's outbound mail through a farm of
postfix servers that will actually do the real queueing, do all the
lookups, etc.... The first postfix server winds up essentially being
an application specific Layer 4 switch, and balances the load across
the outgoing farm of servers.

        What is hard to understand about this concept?

> We are using Veritas to stripe/mirror over a bunch of spindles.
> I understand that I/O subsystem must be fast.
>
> Extent-based file system (VFS as opposed to UFS), would not buy
> as much, as it is whole buncha of smaller files, not a few large
> ones.

        But VxFS does have the advantage that it is a journaled
filesystem and has a commit log. It may not be quite as fast in this
role as *BSD with softupdates, but it should be quite quick.

> Using memory-based FS (such as /tmp on Sol 2.6 for example), is
> blazing fast, but has its drawbacks (if the system dies before
> the generated messages are copied into more persistent storage).

        You could use a memory-based filesystem for the first level
postfix server (the files won't live long on it anyway), or you could
use a solid-state disk. I've found units on the 'net that store up
to 18GB, with battery back-up, etc....

        I still think you may want to take a look at the paper I
presented at SANE '98, entitled "Sendmail Performance Tuning for
Large Systems". Most of the concepts should also be applicable to
Postfix (or are already implemented in postfix), and in fact Wietse
was a large influence on the paper as it was presented.

        See <http://www.shub-internet.org/brad/papers/sendmail-tuning/>. 

-- 
  These are my opinions and should not be taken as official Skynet policy
=========================================================================
Brad Knowles, <blkskynet.be>       Sys. Arch., Mail/News/FTP/Proxy Admin

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