The CacheDirLength directive sets the number
of characters for each subdirectory name in the cache hierarchy. It can
be used in conjunction with CacheDirLevels to
determine the approximate structure of your cache hierarchy.
A high value for CacheDirLength combined
with a low value for CacheDirLevels will result in
a relatively flat hierarchy, with a large number of subdirectories at each
level.
The result of CacheDirLevels* CacheDirLength
must not be higher than 20.