Re: [squid-users] Large Files and Reverse proxy

> Goal maximise byte hit rate to alleviate bandwidth issue across a limited
> connection (till it is upgraded, or the systems relocated).
>
> I have squid configured as a reverse proxy, and that I now have some free
> bandwidth shows it is doing something useful - much thanks!
>
> However revisiting my bandwidth statistics surprised me, that I'm still
> shipping a lot more duplicated content over our connection than I
> expected,
> to the Squid proxy. The biggest offender being a WMV file (it was the
> biggest
> offender first thing this week when I realised I hadn't set the maximum
> size
> of objects high enough to get it cached! It is still the biggest
> offender).
>
> For various reasons we have a number of multimedia files on this end of
> the
> connection, all large, and all with no explicit expiry information (which
> I
> can adjust if it helps).

That will help. Enormously. The longer it can be explicitly known
cacheable the better (RRC states only up to a year though).

>
> What I am hoping is that I can persuade Squid to do a "TCP_REFRESH_HIT"
> and
> burn 350 odd bytes instead of 8 MB when serving our most popular WMV file
> across this connection, or other media files it has cached.
>
> Squid has 420MB of RAM and 17GB of cache (now all populated).
>
> Tuesday, before the cache was full, it was behaving as I expected, since I
> explicitly tested the top WMV file after spotting the object size mistake.
> And now it intermittently does what I want it to. I assume this is simply
> that the cache is full, and that it choosing to drop this object from
> cache.
>
> I see advice to try "heap LFUDA" as the cache policy for maximizing byte
> hit
> rate - which I will try.
>
> However are there other likely "gotchas" with handling larger files?

Some people find it more efficient to store them on disk rather than in
memory. If your squid is already 64-bit or handling it nicely then no
problem.

>
> Are there other levers to twiddle to persuade Squid to hang onto larger
> files?
>
> I'm seeing HITS or REFRESHES about 50% of the time, the other 50% are
> straight
> TCP_MISS for my worst WMV. Bandwidth figures suggest similar results for
> other files.
>

Amos
Received on Fri Aug 29 2008 - 02:40:24 MDT