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© December 2004, ADIC 3
• 4 = Sets scsi_verbose flag.
• 8 = Sets select_debug flag (in libsched select_drive function).
• 15 = ALL: 1+2+4+8
• Enhanced Cache—There are enhancements to the AMASS feature Enhanced Cache Control. The
core of AMASS is a cache in which data is held prior to migrating to/from media. The cache is broke
up into cache blocks whose size is configurable. Without the Enhanced Cache Control feature
turned on, AMASS reuses cache blocks which are the oldest on the cache.
With Enhanced Cache Control the cache blocks are allocated to cache block lists. Each of these
lists can then be weighted to control from where cache blocks are acquired. The cache block lists
are then associated with AMASS volume groups. AMASS volume groups allow users to group data
in a AMASS directory with a set of volumes in the tape/optical library. When associating a volume
group to a cache block list, the user can do so for read or writes. So once a file is written to cache,
it is then migrated to tape, and could be made to persist in cache by having the file's volume group
be associated with a highly weighted cache block list.
• Eight cache block priority levels are maintained within the AMASS files system.
• Cache block reallocation priorities are established on a volume group basis. No additional
controls are provided for individual directories or files.
• For each volume group, two cache list priorities (one through eight) are assigned. One list is
assigned for reads and the other list is assigned for writes.
• For a particular volume group, the priority can be changed dynamically for the read/write
priority, but the new priority takes effect for cache blocks accessed or modified after the change.
• Each cache list has an additional weighting factor that is used to compute a score for the cache
block list. The score for a particular list is the weighting factor multiplied by the access time of
the oldest cache block on the list.
• A special weighting factor can be assigned specifying that all other cache lists should be
searched before this list is searched. This stops the oldest cache block age from being used to
create a score for a given cache list.
• The weighting factor can be changed dynamically and the new settings immediately take effect.
• If the weighting factor is assigned to multiple cache lists, an implied priority is established based
on the cache list number (in other words, search the cache list with the lower priority level first).
• The special weight factor for list 1 CANNOT be set to zero. Initially, all of the cache blocks
available to the system live in the first list and setting the weight factor on this list causes
undesired effects. Setting the weight to zero is interpreted by the system as ìonly use this list if
no other cache blocks in the system are available.î The moment a file has been written to media
and the cache blocks are put back on the free list, the blocks will be re-used immediately, even
if there are thousands of unused cache blocks available on list one (with a weight of zero).
• A cache block is reallocated from the list with the highest score for all eight cache priority lists.
• All cache blocks exist on one list. Cache block reallocation occurs on a first-in-first-out basis.
• medialist—Users with large volumes can limit the medialist output to show only drive status.
Usage: ./medialist [-v] [-j jukebox_number] [-D] [-V] [-T] [-M] [-x] [-j];
where:
• -D Shows Drive information only.
• -v Shows barcode information (Valid only for SCSI attached libraries).
• -V Shows volume information only.
• -T Shows Transport information only (not valid for network attached library).
• -M Shows Mailbox information only (not valid for network attached library).