File descriptors

Todd canadaboy at
Tue Feb 24 18:14:27 UTC 2009

Good day,

We ran into an issue this morning with some caching DNS servers.  One
of the zones we heavily rely on was having DNS issues, which appears
to have been causing very slow responses to us.  The servers in
question handle about 500queries/second.

These particular servers are configured with "recursive-clients 5000",
which we thought would be sufficient.  However, before we even reached
5000, the server started boinking because of "socket: too many open
file descriptors" errors in syslog.

So, the question is, do we need a 1:1 mapping of fle descriptors to
max queries, + overhead for named?  From reading, I see that a socket
uses a file descriptor, so my assumption is yes, but I wanted to check
with Those Who Are Wiser Than I before I write a change ticket to get
these things fixed.

If I do need to allow more file descriptors, what is the best method
to ensure that the named process has an appropriate number?

Thank you very much for your help,


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