[squid-users] Re: Squid 3.2.6 & hot object cache

>Rock and COSS storage types however are far more optimized for speed,
using both disk and RAM storage in ther normal "disk" configuration. <

Amos,

haven't you been a little bit too "generous" in your comments, especially
this referred one ?

I looked at the docs both for COSS and Rock, and the following excerpts made
me a bit skeptical:

1) COSS:
Changes in 3.3 cache_dir
    COSS storage type is lacking stability fixes from 2.6

When I read such a statement, I refuse to use this feature in a production
environment. Even in case, it has a lot of speed advantages. One crash might
wipe out all speed advantages.

2) Rock:
http://wiki.squid-cache.org/Features/RockStore#limitations
2a) Rock store is available since Squid version 3.2.0.13. It has received
some lab and limited deployment testing. It needs more work to perform well
in a variety of environments, but appears to be usable in some of them.
2b)Objects larger than 32,000 bytes cannot be cached when cache_dirs are
shared among workers.
2c)Current implementation uses OS buffers for simplicity.

When reading 2a) I start to be cautious again :-)
2b) tells me, it very much depends upon the mean size/standard deviation of
the cached objects, whether using Rock really has an advantage. Might change
in the future with Rock-large, though.
2c) Makes the theoretical approach to evaluate performance advantages of
Rock almost impossible. Because you always have to consider the filesystem
used, with the respective options, having a huge impact on performance. So
the only serious approach right now to advocate possible performance
advantages would be after quite some benchmarking, using real workloads.
Which certainly are very site specific.
Because of the basic principle of Rock and Rock-large (which are like
filesystems themselves), using raw disk-I/O is possible in the future, at
least, which MIGHT THEN justify a general statement "much more optimized to
speed".

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