Re: [squid-users] fourth cache off??

From: Jon Kay <jkay@dont-contact.us>
Date: Thu, 20 Dec 2001 13:26:20 -0600

> The Swell entry did a lot better on hit time than previous cacheoffs,
> and I'm guessing that the underlying cause was largely the RAM disk.
> It makes sense, since this workload has a median file size that is
> smaller than its mean file size.

...which, of course, is true in spades for real cache workloads.
Your point?

> b) Is this approach scalable? The three entries with better hit times
> had throughputs roughly 4-20 times as high. So, if your system can
> only hold 4GB of memory, the RAM disk approach has less than a
> factor of 2 from its current numbers before one would expect some
> degradation.

That's a silly comparison. You configure a given system to do best
with the load it's given. One would almost think you were bringing
this up to highlight iMimic's better throughput :-). Permit me to
remind you of Squid's superior latency improvement/$ :-).

> c) Is the comparison fair? Since polygraph/polymix is a disk-bound
   workload . . .

Of course it's fair. He had to pay the cost of the RAM in his entry.

> d) Finally, there's the issue of whether stable storage is important
> for a proxy or not. If a large fraction of the content is stored on
> a RAM disk, a reboot or power loss is a significant concern. My
> conclusion is that if you can do without the RAM disk, it's
> probably better to build a cache that uses stable storage for files
> and uses memory only as a hot object cache.

It's a CACHE. When the power goes out, your hit rate suffers for
awhile and then you come back. If your cache is located in
Afghanistan, then I recommend going with the stable storage.

-- 
Jon Kay        pushcache.com                      jkay@pushcache.com
http://www.pushcache.com/                             (512) 420-9025
Squid consulting				  'push done right.'
Received on Thu Dec 20 2001 - 12:27:50 MST

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