Squid and first-level subdirectories & second-level subdirectories on ext3/4

Ralf Hildebrandt Ralf.Hildebrandt at charite.de
Fri Aug 13 10:00:55 UTC 2010

Squid, a proxy, is by its nature, storing large amounts of relatively
small files in it's cache.

As config optins it's offering:

#       'Level-1' is the number of first-level subdirectories which
#       will be created under the 'Directory'.  The default is 16.
#       'Level-2' is the number of second-level subdirectories which
#       will be created under each first-level directory.  The default
#       is 256.

Meaning one has

/squid-cache/(16 dirs)/(256 dirs)/(the small files)

so the total number of small files in the cache is (hopefully) evenly
distributed to 16*256 directories.

But is that optimal for an ext3/4 filesystem? What is the point of
using 16 for the first level and 256 for the second?

Wouldn't 64*64 (which equals 16*256) be better when it comes to
finding the files on disk?

Ralf Hildebrandt
  Geschäftsbereich IT | Abteilung Netzwerk
  Charité - Universitätsmedizin Berlin
  Campus Benjamin Franklin
  Hindenburgdamm 30 | D-12203 Berlin
  Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
  ralf.hildebrandt at charite.de | http://www.charite.de

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