Re: New cache relationship - spouse?

From: Craig Bishop <>
Date: Mon, 18 Nov 1996 17:12:23 +1100

Ong Beng Hui wrote:
> > Do people think this would be good thing to see? I foresee that as
> > caches increase in popularity, we will start running into the same barriers
> > with a single machine being asked to handle too much load (much as is
> > happening right now with web servers) and thus the need to start load sharing
> > (and coherently managing that) will become necessary. The sibling relationship
> > is a good start, but we (at Connect) believe spouse-ing may be the next step.
> Prehaps, "proxy-only" options under "cache_host" tag will
> help for a time being.

That option is currently being used between those two caches. The problem
is that, if for whatever reason a object gets duplicated on the two caches,
it can be there forever.

Once a really popular object is stored on both caches it will never get
deleted. We have already seen instance where we have 25% overlap on objects
which is not very efficient. The less overlap the better we can serve

Stewart Forster wrote:
> The protocol would then be.
> 1) If the source has the newest object, get that and cache it. (as usual)
> 2) If a spouse has a newer object than me (and the source is not newer than
> my spouse's copy), get the spouse's copy and remove my copy of the object
> from the swap.
> 3) If my copy is newer than everyone else's, simply return it. (as usual)

I would suggest we could even simplify that by just asking any spouses
whether they have a "FRESH" copy of the object. If so get it from the
spouse and remove the local copy. If not do a IMS GET.

Cheers, Craig

Craig Bishop - Technical Manager
Received on Sun Nov 17 1996 - 22:13:53 MST

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