recursive-clients, what value ?

[Kevin Pickard]

Mikael <pub.nospam at grizzli.org> wrote in message news:<caknas$1500$1 at sf1.isc.org>...
> Hello,
> 
> I'm working on bind 9.2 on linux mandrake and I had lots of logs 
> containing :
> 
> Jun 14 09:23:30 hostname named[1045]: client: client 127.0.0.1#34559: no 
> more recursive clients: quota reached
> Jun 14 09:25:22 hostname named[1045]: client: client 127.0.0.1#34565: no 
> more recursive clients: quota reached
> 
> I read that increasing "recursive-clients" could help. I'm going to set 
> it to 2000 but is there a way to know what would be a good value ?
> Is there a way to monitor in real time the number of simultaneous clients ?
> 
> Thanks in advance,
> 
> Mikael

Determining a good value for the "recursive-clients" option depends on
your environment.  From the logs you included, it looks like you're
just barely peaking over the default 1000 simultaneous recursive
queries every now and then, (because you only had two entries, and
they were a couple mins apart).  I'd guess that, unless you expect
significantly more recursive queries in the future, that bumping
"recursive-clients" to 1100 should probably suffice.  If you find that
you're still generating "quota reached" logs like above, bump it up a
little more until the messages subside.

Setting it at 2000, as you mentioned, is probably more than you need
-- theoretically a doubling of your current simultaneous recursive
query capacity.

Lastly, keep in mind that, as the Bv9ARM mentions, "each recursing
client uses a fair bit of memory, on the order of 20 kilobytes".  Your
amount of physical memory ultimately dictates how high this value can
go.  We have many servers in production which have this value set
above 3000, but they have the RAM to back it up.

Best Regards,

ksp