Re: Finding the Bottleneck
Memory memory memory! True, memory is not currently a limiting factor,
but it likely could be if he were running BIND locally. As for making
sure that the server is not authoratative for other domains, that will
help keep other DNS demands to a minimum.
The mail server will chew up a load of memory (or can anyhow.. his
doesn't seem too bad). A highly-utilized DNS server will also chew up a
load of memory. You do not want the DNS server to swap, so you need to
have enough memory to be sure it can cache enough information.
As for speed, if you have a machine on a LAN set up as a caching-only
DNS server (that's what I was trying to say before), I'm thinking I'll
take the LAN latency hit over having the MTA competing for resources
with the DNS server.
Other than that, yea, some kind of RAID solution would be cool for him.
I'd also look at making sure /var/log is on a seperate drive from
/var/spool/mail. I saw an email that indicated that /swap was seperate
from /var/spool, but nothing about where the log files were located. Not
synching after evey write will help obviously, but I recall seeing quite
a benefit from seperate drive for /var/log and /var/spool.
Russell Coker wrote:
> On Friday 08 June 2001 05:47, Rich Puhek wrote:
> > In addition to checking the disk usage, memory, and the other
> > suggestions that have come up on the list, have you looked at DNS?
> > Quite often you'll find that DNS lookups are severely limiting the
> > performance of something like a mailing list. Make sure that the mail
> > server itself isn't running a DNS server. Make sure you've got one or
> Why not? When DNS speed is important I ALWAYS install a local DNS.
> Requests to 127.0.0.1 have to be faster than any other requests...
> > two DNS servers in close proximity to the mail server. Make sure that
> > the DNS server process isn't swapping on the DNS servers (for the kind
> The output of "top" that he recently posted suggests that nothing is
> > with 128 MB of RAM as your DNS server. Also, if possible, I like to
> > have the DNS server I'm querying kept free from being the authoratative
> > server for any domains (not always practical in a real life situation,
> > I know).
> How does that help?
> If DNS caching is the issue then probably the only place to look for a
> solution is djb-dnscache.
> http://www.coker.com.au/bonnie++/ Bonnie++ hard drive benchmark
> http://www.coker.com.au/postal/ Postal SMTP/POP benchmark
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