file descriptor exceeds limit

Matus UHLAR - fantomas uhlar at
Thu Jun 18 11:00:52 UTC 2015

On 17.06.15 22:39, Shawn Zhou wrote:
>BIND on my resolvers reaches the max open file limit and I am getting lots

>After I increased the max-socks (-s 8192) to 8192, I no longer saw the file
> limit error from the log anymore; however, I am still many SERVFAILs.

no other errors?

>Our resolvers were doing about 15k queries per seconds when this was
> happening and those were legit traffic.  I am aware that I am setting
> recursive clients to a very high number.  Those resolvers are running on
> 12-cores cpu and 24G RAM hardware.  cpu utilization was at about 20% and
> plenty of RAM left.

>I am wondering if I've reached the limit of BIND for the amount of
> recursive queries it can serve.  Any other tunings I should try?

maybe changing number of recursive-clients, max-clients-per-query.

Does EDNS work for you? EDNS problems often result to increased number of
TCP queries which slows down resolution ...

> By the way, the resolvers are running RHEL 6.x.

precise BIND version would help a bit more... seems RH6.6 contains 9.8.2 but
that may be different for older RH6 versions.

Matus UHLAR - fantomas, uhlar at ;
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