Index cache management

How the index cache is managed in IBM Storage Archive Library Edition.

If a cartridge is modified outside the file system, the index might become out of sync with the cache. This might occur when IBM Storage Archive LE is either unmounting the library or the user removes the cartridge from the library and reinserts it. If it occurs, directory listings in the file system become out of date. When IBM Storage Archive LE starts, it retrieves the inventory from the changer and removes cache files for any cartridges that are no longer present. If disk caching is enabled, the cache is read into memory when IBM Storage Archive LE starts. The disk cache for a cartridge is written whenever the cartridge is unloaded from a drive.

IBM Storage Archive LE always loads a cartridge when a file is opened or any metadata update or read/write request is received. When IBM Storage Archive LE loads a cartridge, it always verifies that the volume matches the contents of the cache (volume Universal Unique Identifier and medium auxiliary memory or MAM parameters). If the data in the cache is outdated, IBM Storage Archive LE reads the latest MAM/labels/index from the cartridge and immediately starts to use it. When that occurs, the directory listings become updated again.

Attention: The index cache is enabled by default, but can be disabled by specifying the -o no_library_cache option. To optimize performance, however, the index cache must be enabled. If any of the cartridges in the library can be modified outside the file system, the index cache must be disabled to keep it up to date.