full socket buffers

sthaug at nethelp.no sthaug at nethelp.no
Sat Dec 18 21:53:42 UTC 2010

> > We're also running 4.1.1p1, on FreeBSD 7.3-STABLE. Server hardware is
> > Dell PE 1850, with two SCSI disks in a RAID-1 configuration. We have
> > around 100k leases on two servers in a failover pair, with most of the
> > pools on 24 hour leasetime. We don't see the problem you're seeing.
> We're running the dhcpd service on two IBM x3550 servers in failover,
> both have two 74GB 15k disks in RAID-1 so very similar to yours.

How many DISCOVERs and REQUESTs do you handle per second? Do you have
battery backed cache for your RAID-1 config? Have you tried gstat, and
looked at the %busy column?

An additional point which might be relevant - we run our failover
configuration with a "delayed-ack 28" setting. This cuts down on the
failover traffic (including disk I/O). Yes, we know there have been
some warnings about delayed-ack - however it has never given us any
problems. Note that it needs to be explicitly compiled in.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no

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