hardware and OS requirements

[Kevin Darcy]

Dan Fulbright wrote:

> Can anyone point me in the right direction to find some discussion about
> hardware and OS requirements for variuos BIND setups?  I am going to be
> setting up a DNS server for about 10,000 to 20,000 domains, and would like
> some idea of what kind of machine(s) I would need.  My instinct is to use
> Linux, but I would be open to others (mainly BSD-based).  I need to know
> things like, how much RAM and hard drive space, and, if I use Linux, what
> file system types, etc.

I think this has been discussed on bind-users intermittently; did you try an
archive search? I'm not sure where else you'd look for that kind of
information.

I can tell you, though, that "number of domains" is not the only factor you
need to consider here. For RAM, a much better parameter to consider is the
total number of records. I've heard rules of thumb like "100 bytes per
record" and so forth. There is a little bit of overhead associated with each
zone, but unless all of your zones are tiny, the bulk of the storage will be
taken up with the records themselves.

Another very important metric is your query volume. This is going to impact
your CPU and your network capacity.

Disk space is generally of secondary importance to a DNS server. Even if you
have millions of DNS records, that's not likely to take up more than a
gigabyte or two of storage. Disk *performance* only really comes into play
when named is starting up or reloading, and it shouldn't be necessary to do
that very often (you didn't say what method you were using to maintain your
DNS data, but if you use Dynamic Update, then it's never necessary to reload
whole zones, and even if you're munging zone files, it should never be
necessary to load more than one zone at any given time). In any case, the
multithreaded nature of BIND 9 should help with your reload woes, since it
allows the nameserver to answer queries even while it is reloading. Of
course, you could also achieve parallelism by simply implementing multiple
DNS servers...


- Kevin