iXOS-JUKEMAN stores the recently read directories in a memory pool for fast
access. The default size of this memory pool is 4 MB, and can be changed with
the parameter mpsize (see "Server parameters" on page 125). An
additional permanent directory cache can also be set up. It is stored as a file
on hard disk and is specifically recommended for larger installations.
The directory cache is not a relational database, but an performance-optimized
list which is protected by the journal against data corruption even in the case
of a power failure.
The cache is filled dynamically when clients access the server and request
non-cached directories and files. Internally the caching occurs under the
following conditions:
1. If a directory is accessed and it is not found in the cache, then it is
filled into the directory cache.
2. If a new disk is inserted into a drive, iXOS-JUKEMAN checks to see if the
root directory is in cache. If it is not, the parameter autodc (see
section "Server parameters" on page 125) determines what happens next. If set
to 0, no caching is performed. If set to 1, caching is performed only if a
permanent hard disk directory cache is configured. When set to 2, JUKEMAN will
cache the entire directory structure.
When setting the size of the directory cache, keep the following in mind:
1. Each file requires 25 bytes plus the length of the file name.
2. Each directory requires 100 bytes plus the length of the directory name.
3. Administration of the cache consumes approximately 15% of the space, so you
have to add about one sixth of the totals of items 1 and 2 to the sum.
4. If a disk contains extensions in Rock Ridge format, you must allow for the
additional space occupied by the rock ridge name.