Supporting large caches (> 4GB) in BIND?

Shumon Huque shuque at isc.upenn.edu
Mon Feb 15 17:29:56 UTC 2010


On Mon, Feb 15, 2010 at 05:46:25PM +0100, sthaug at nethelp.no wrote:
> > I've recompiled the nameserver as a 64-bit program and confirmed
> > that they can now exceed 2GB. But I'd like to be able support
> > much larger cache sizes. We have some CS researchers on campus
> > that are making heavy use of our recursive resolvers. I'd like
> > to support their research but I need to significantly increase
> > our cache size to do so, and at the same time not allow the 
> > nameserver to eat up all of the system RAM (we currently have 
> > 16GB per server).
> 
> Have you *measured* the hit rate of your current BIND resolvers
> with different cache sizes? How many queries per second are you
> trying to support?

We do about 3,000 queries/second typically. I haven't measured query
-rates vs cache sizes. We've had max-cache-size set to 3GB for a long
time, but the process never exceeded 2GB until recent crashes prompted 
recompilation as 64-bit.

> I'm not ruling out the need for cache sizes much larger than 2 GB,
> but I *would* be somewhat surprised if you see a large improvement
> (law of diminishing returns etc).

May be. Although as long as it doesn't impact performance negatively,
I'm willing to let the cache grow. The researchers in question are
querying tens of millions of domain names, and then periodically obtain
dumps of our cache for data analysis.

--Shumon.



More information about the bind-users mailing list