High read IOPS with file backend (re-visited)

[Bryan Stillwell]

Last month I reported an issue I was seeing where varnish was
producing a lot more read IOPS than I was expecting:

https://www.varnish-cache.org/lists/pipermail/varnish-misc/2013-August/023275.html

There were big jumps in read IOPS around the time objects started
expiring and also when the cache filled up, but they were pretty high
before those jumps as well.  I was wondering if anyone has an idea of
what might be causing so many more reads compared to what nginx needs
(for example nginx needed just 200 read IOPS with a full cache, but
varnish needed 5,700 read IOPS to handle 337 requests/sec)?

Thanks,
Bryan