Re: The Mythical 30% Hit Rate

We can hold at 30% by-byte on ours (5 boxes, 4 of which are 24x4Gb disk, 1.5Gb
RAM Sun 450's). They're not talking to each other at the moment - ICP was too
high a load, digests weren't _quite_ stable, and we only gained an extra 3%
or so anyway - and we're acting as upstream for the likes of Dancer and Tom
;) - we're a national provider, so most of the traffic is done by
downstream ISP's who are already cacheing and using peering points in
preference.

Oh, around 25-30Gb/day throughput on each cache - averaging
150-ish-K hits/hr, peaking at 260K hits/hr. Personally, I think they've
got slightly too much disk in them, but that remains to be proven.

We had them at 40% for a while last year, but they're fairly sensitive to
environmental changes - peering usage is up, dynamic pages are up, traffic
mix has changed a bit since then...

KevinL

>>> Dancer wrote
> tom minchin wrote:
> >
> > On Sat, Nov 20, 1999 at 06:56:37PM +0800, Miguel A.L. Paraz wrote:
> > > Hi all,
> > >
> > > I'm curious about the oft-quoted 30% optimal hit rate "by experience".
> > > Is this on requests or on bytes? I got a server that's doing 30% on requ
ests,
> > > and 15% on bytes, on 9 GB of cache_dir.
> > >
> > > I'm wondering if adding 9 GB more disk will increase the byte hit rate.
> > > One reason it might not, is because this cache handles requests of
> > > downstream caches and not end-user requests.
> > >
> >
> > On our cluster, we get ~30% bytes and ~34% requests on 45gig, I suspect the
re's
> > a sweet spot as it's pretty close to what we get on the 20gig cluster membe
rs.
> >
> > If you do service downstream caches, then you don't get good statistics as
> > the downstream gets the client hits.
> >
> > tom@interact.net.au
>
> We get ~62% by hits and ~45% by bytes across 7 servers on one of our
> deployments. This is with a percentage of the ~1,400 connected customers
> having a deployed proxy of their own (each customer supports around a
> thousand users).
>
> Our customers are a niche market, though, and tend to have similar
> browsing habits.
>
> D
>
>

--------------- qnevhf@obsu.arg.nh ---------------
Kevin Littlejohn,
Technical Architect, Connect.com.au
Don't let the Govt censor our access to the 'net -
http://www.efa.org.au/Campaigns/stop.html
Received on Mon Nov 22 1999 - 17:13:50 MST