[Mailman-Users] Hardware Requirements

[Nigel Metheringham]

On Thu, 2002-07-11 at 16:59, J C Lawrence wrote:
[I have reordered the quotes here - sorry if I have broken the meaning]
> Journalling actually is a loss in this sort of scenario due to the extra
> tracking and buffer copy overhead.  The nice thing about ReiserFS and
> XFS in particular is that the other optimisations they make more than
> make up for that cost.

But full data journalling on an MTA type system can gain you performance
by having the disk head basically moving linearly as the journal
writes.  On a fast turnround system by the time it comes to writing out
the actual file contents and directory entries and stuff, the file is no
longer pertinant (ie already been processed/delivered etc) and so the
write is optomised out....

> MTAs are limited by physical disk IO.  They do lots of reads and writes
> (which can be cached), and more importantly, do lots of calls to sync()
> and close() which explicitly flush those caches down to metal.
... for various definitions of metal - ie a flushed journal for ext3,
and probably some form of NVRAM for a decent hardware RAID controller.


> >> c) go SCSI with /var/spool/MTA, /var/log, and /var/www on different
> >> spindles.
> 
> > Yes, definitely. Also, for a system that will have this many files on
> > it, consider using a journaling filesystem rather than ext2. I have
> > had superb success with Reiserfs, but there are also IBM's JFS, SGI's
> > XFS, and the ext2-compatible ext3. Reiserfs has significant
> > performance improvement over ext2 and ext3, especially on small files,
> > and it might be a good choice for this system.

SCSI or even better a *good* hardware RAID controller.  Filesystems are
a religious issue but I still keep hearing more mentions of resiserfs
going completely tits-up for my liking.  Great ideas but there still
seem to be some problems there.....

	Nigel.
-- 
[ Nigel Metheringham           Nigel.Metheringham at InTechnology.co.uk ]
[ - Comments in this message are my own and not ITO opinion/policy - ]