[Mimedefang] Looking for more ramdisk benefits

Chris Myers chris at by-design.net
Fri Feb 6 09:52:10 EST 2004


----- Original Message ----- 
From: "Juergen Georgi" <georgi at belwue.de>
To: <mimedefang at lists.roaringpenguin.com>
Sent: Friday, February 06, 2004 8:42 AM
Subject: Re: [Mimedefang] Looking for more ramdisk benefits


> > I moved /var/spool/MIMEDefang to a ramdisk and got a 20% improvement in
> > scan time (It's a slow old disk in the box)
> > Before I spend ages experimenting, has anybody found any worthwhile
> > improvement by moving other stuff to ramdisk, [...]
>
> Bayes db lookups hit the disk on every message. I'm thinking about
> moving bayes_path entirely to a tmpfs. Of course there must be
> a mechanism to save the precious bayes data across reboots - maybe
> with one or two snapshot backups per day to persistant storage.
>
> Has anyone done this before?

Yes, I have done this and it's incredibly helpful on a higher-volume system.

You should at least write scripts that do roughly:

1) At system boot:
- Mount the tmpfs
- Copy the backup bayes database to the tmpfs

2) At system shutdown:
- Copy the bayes database to the backup location
- Dismount the tmpfs

If you lose a few days (or, often, a few weeks!) of Bayes database it's not
a problem.  Losing a few months, or all of it, would generally be considered
"bad".

Do make sure you have enough RAM to keep everything from swapping and
paging.  The moment a system starts swapping and paging, performance will
drop in the the toilet.  I probably wouldn't even consider this trick with
less than 512MB of RAM (and preferably 1GB).

Chris Myers
Networks By Design




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