Re: [squid-users] accelerator farm: optimizing the sibbling_hit

mån 2003-03-03 klockan 15.57 skrev Ard van Breemen:
> Hi,
> I am busy optimizing an accelerator farm using 2.4.4.
> It currently contains the following *easy* patches:
> - remove updates into client_db, this makes sure that when you
> have a major site, your accelerator won't run out of memory.
> This means commenting out the few calls to clientdbUpdate

Which already is done in the form of the "client_db off" directive in
squid.conf..

> - Allow refreshes to be done by peers.
> This means removing a test in neighbors.c, function
> peerAllowedToUse, test: request->flags.refresh

You also get the same or at least similar effect by setting
"prefer_direct off" IIRC, but this probably only applies to parents.

To allow refreshes via siblings you must also change Squid to not use
"only-if-cached" when requesting the object from the sibling, or else
the request will be rejected by the sibling.

> I am now thinking of the next ICP improvement, because having the
> same aging criteria on all accelerators will give the following
> problems: it will expire on all servers at exactly the same time.

I would probably solve this by adding some expiry fuzzyness on the web
server, and also by changing Squid to allow multiple cache revalidations
of the same object to be collapsed into one.

-- 
Henrik Nordstrom <hno@squid-cache.org>
MARA Systems AB, Sweden