On 15/12/10 14:38, Michael Hendrie wrote:
Hello List,
I have server running 3 instances of squid-3.0.STABLE19 using a
configuration similar to that documented at
http://wiki.squid-cache.org/MultipleInstances. Each instance has all
other instance configured as siblings using the "proxy-only" directive
to allow sharing of cache without duplicating objects. This setup is
working very well and has increased server performance by over 50%.
I'm now trying to get an accurate indication of byte savings I'm
achieving with this configuration however I'm not sure that the
calculations I'm using are giving the correct results. Because each
instance maintains a separate cache_dir this seems to be a little
difficult to calculate. When instance 1 records a request as a MISS it
may in fact be a HIT (from an entire system point of view) if the object
is retrieved from the cache of instance 2 or 3.
Using a combination of "squidclient mgr:counters" and SNMP, I grab
counter values from each instance, tally and use the following formula
to calculate the byte hit ratio:
(mgr:counters:client_http.hit_kbytes_out +
snmp:cacheClientHTTPHitKb.sibling_addresses) /
(mgr:counters:client_http.kbytes_out -
snmp:cacheClientHTTPHitKb.sibling_addresses) * 100 = % cache byte hit ratio
Using this formula, I always seem to get inconsistencies between what
squid reports and what my benchmarking tool reports (web-polygraph). In
the few cases I've checked so far, squid is always reporting a 4-5% less
byte hit than what web-polygraph reports.
That sounds about the size of header overheads to me.
Give 3.2 workers a try out now and see if that is usable. The stats
calculations are fixed there for multiple workers.
Amos
--
Please be using
Current Stable Squid 2.7.STABLE9 or 3.1.9
Beta testers wanted for 3.2.0.3
