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Re: Finding the Bottleneck

On Thursday 07 June 2001 20:14, Jason Lim wrote:
> I agree with you... it seems more and more likely that the Disks are
> the limiting factor here.
> I guess the next big thing to do would be to run some form of Raid
> (software or hardware) for the mail queue.
> Does anyone know of a cheap but adequate raid hardware solution? The
> one's I've seen seem to cost quite a bit. I know that the common cheap
> ATA100 Raid cards available now (using the Highpoint HPT370) don't work
> properly on Linux beacuse of the bad driver support. Anyone know of an
> alternative?

For RAID hardware there are three criteria you desire, reliability, low 
price, and speed.  You can have at most two of them.

There are a number of cheap hardware RAID solutions out there which would 
be quite OK for home use, but not for a server of the type you are 
considering.  If you had several redundant servers with the same data 
then one of the cheap hardware RAID solutions might do well though.

> Actually... do you think setting up a seperate box (connected via NFS)
> PURELY for mail queue processing would help at all? Or would the
> bottleneck then be shifted to NFS?

If the NFS server has the same disk system then you will only make things 
worse.  Anything you could do to give the NFS server better IO 
performance could more productively be done to the main server.
Also many of the common Unix mail server programs are specifically 
designed to have the queue on a local file system with standard Unix 
semantics (Inode numbers etc).  Qmail is one mail server that I have 
found to not work with it's queue on NFS, I haven't seriously tried any 
others.  I've CC'd Brian May because he does a lot more NFS stuff with 
Debian than most people and he may be able to advise you.

I suggest just getting 4 IDE disks and putting everything on a software 
RAID-10 apart from /boot (which must be RAID-1 for the boot loader to 
work).  It'll get the most bang for the buck!

http://www.coker.com.au/bonnie++/     Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/       Postal SMTP/POP benchmark
http://www.coker.com.au/projects.html Projects I am working on
http://www.coker.com.au/~russell/     My home page

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