On 27 September 2001, Craig Sanders <castaz.net.au> wrote:
> On Thu, Sep 27, 2001 at 11:37:46AM +0300, Liviu Daia wrote:
> > On 26 September 2001, Alexander <mlambrosa.it> wrote: [...]
> > > Title: the best mode to deliver 1.000.000 email messages
> > > (recipient are ALL different and email are ALL different) in few
> > > hours during a single delivery session.
> > >
> > > You suppose to have a SMP Linux server (i.e. dual P-III 800 Mhz,
> > > 512 MB Ram, SCSI Raid 5, kernel 2.4.9 and RaiserFS) and a good
> > > internet connection (4 Mbit/sec full bandwidth) and a fast DNS
> > > server near me.
[...]
> > Wietse already explained how to setup Postfix for best
> > performance. Here's an additional checklist, mainly for the rest of
> > the system:
> >
> > - if possible, use OpenBSD or FreeBSD with softupdates rather than
> > Linux;
>
> alternatively, configure and use linux properly rather than believe
> propaganda.

    Better yet, try both (take your time to tune them), then choose.

> > - if you insist on using Linux, use a 2.2.x kernel, not a 2.4.x one,
> > and turn OFF the swap; buy more RAM if you feel you're running out
> > of it;
>
> 2.4.x kernels are perfectly adequate, indeed much better than 2.2.x
> kernels.

    Not in my experience. Of course, YMMV.

> and there's no need to turn off the swap.

    If you run into swap, performance would suck no matter what. For
some reasons, Linux 2.4.x seems to exacerbate this problem (again, in my
experience; standard disclaimer apply).

> adding RAM is always a good idea.
>
> > - use RAID 0+1, not 5, and (if you have that choice) mirror the
> > stripes instead of striping the mirrors;
>
> my testing a few months ago proved that RAID5 is significantly faster
> than RAID0+1 for the kind of disk loads you see on mail servers.

    That's because:

> the tests were performed using the exact same hardware, and same
> software, on the same machine - dual P3-866 with 512MB RAM, hardware
> raid card with 32MB non-volatile cache, and 6 x 18GB IBM drives.

    How many of the RAID cards out there have 32+ Mb of non-volatile
cache, and how much do they cost?

[...]
> > - use ext2; Xfs and Jfs are not yet ready for prime time, and
> > everything else is slower than ext2 for mail handling;
>
> ext2 would be one of the worst choices for a mail server's filesystem.

    Not according to some tests I've seen recently. If you're
manipulating many small files, ext2 performs consistently better than
Reiserfs (OTOH, ext2 loses big time for large files --- but that's not
really relevant here).

> xfs is reliable and ready for prime-time in my experience.
[...]

    On Linux? How nice.

    Regards,

    Liviu Daia

-- 
Dr. Liviu Daia               e-mail:   Liviu.Daiaimar.ro
Institute of Mathematics     web page: http://www.imar.ro/~daia
of the Romanian Academy      PGP key:  http://www.imar.ro/~daia/daia.asc
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