Requests suddenly slow / fine after restart

[Bjoern Metzdorf]

Hello everybody,

we are running 2 varnish proxies with version 1.1.2 on debian etch 
amd64. They are balanced with LVS.

The commandline is as follows:

/usr/sbin/varnishd -P /var/run/varnishd.pid -a :80 -f 
/etc/varnish/default.vcl -T 127.0.0.1:6082 -t 120 -w 1,3000,120 -s 
file,/var/lib/varnish/proxy1/varnish_storage.bin,100G

The proxies cache 2 domains, which only serve static files (no cookies 
in use). there are no special expire options set in varnish config. the 
backend servers (lighttpd) set them.

Recently we had some problems with slow requests. Some static graphic 
files suddenly took several seconds to load instead of the usual 
milliseconds. After a restart of varnish everything was fine again and 
the very same graphic was fast again.

Since then we restart the varnish processes every morning. But 2 days 
ago we again had the "slow delivery" problem.

I have not seen any obvious reasons for that, but I have not yet looked 
deeper into this issue.

Perhaps somebody experienced similar things and found a solution?

Thank you

Regards,
Bjoern