Curious distribution of objects per directory, HASH is buggy or non uniform ???

From: Pedro Ribeiro <pribeiro@dont-contact.us>
Date: Sat, 30 May 1998 18:51:54 +0100

While analyzing the use of the cache disk of my proxy
(squid1.2beta21+patch1+patch2) running in a Alpha433au under Digital Unix
4.0d and i'v noticed something very strange:

issuing the command:

du -k -s cache/*

the results were surprising:

869047 cache/00
919019 cache/01
322627 cache/02
260 cache/03
260 cache/04
260 cache/05
260 cache/06
260 cache/07
260 cache/08
260 cache/09
260 cache/0A
260 cache/0B
260 cache/0C
260 cache/0D
260 cache/0E
260 cache/0F
260 cache/10
260 cache/11
260 cache/12
260 cache/13
260 cache/14
260 cache/15
260 cache/16
260 cache/17
260 cache/18
260 cache/19
260 cache/1A
260 cache/1B
260 cache/1C
260 cache/1D
260 cache/1E
260 cache/1F

the same results are obtained for the second level dirs. i.e. only the three
first dirs are used, i think that this could impact very negativly in the
squid performance ...

I'm i missing something ?, the hash function used should have a uniform
distribution no ??

the cache disk (mounted in /usr/local/squid/cache ) is half full, it's a
4Gig HD.

i'm using 32dirs for the first level and 256 for the second ( in
squid.conf ).

!!!!! i would like if other people can see if the same behaviour are
appening to their caches. !!!!

Best Regards.

[]---------------------------------------------------------------[]
  Pedro Ribeiro
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Received on Sat May 30 1998 - 10:56:16 MDT

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