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T10000 Cartridges
Cleaning cartridge which cleans all four T10000 drive models (CL media
■
identifier)
Media Information Region
The T10000 tape drives use information recorded on each tape cartridge to reduce
access times and manage the useful life of the cartridge. This information is recorded
in the cartridge's radio frequency identification (RFID) chip and at the beginning of
tape in an area known as the media information region (MIR). The information stored
in the RFID is a proper subset of the information stored in the MIR. The media
information falls into two categories: statistical counters and data pointers.
Statistical Counters
Statistical counters reflect use of the cartridge and includes read and write activity,
error activity, cumulative mounts, and other information about its use.
Data pointers
The data pointer information is a directory (map) used to locate the customer (logical)
data on the physical tape media. Because customer data is compressed and written in
drive controlled blocks on the tape, a map is needed to efficiently locate the data after
it is written. This map provides an index between customer data and the physical
block on the tape media. After data is written, the drive accesses this map to optimize
access to the customer data.
To locate or space to customer data, the logical object that identifies the block is
translated to the physical location on the tape media, and the drive determines the
quickest method to read the block. If the block is some physical distance from the
current location, a calculation results in a high-speed locate to the block location and is
followed by a normal speed read.
The existence of the media information is usually transparent to the customer unless it
has a problem. This can occur if the information update fails during a dismount. The
impact of invalid media information occurs in several areas. Because it enables high
speed positioning, invalid media information forces all operations to a slow speed
mode. This has no impact on a sequential read from the beginning of the tape.
However, any operation using locate defaults to a sequential slow-speed read to the
requested block, which can result in longer processing time.
The following sections describe how media information is processed and some
potential implications of problems with the information.
Normal Processing
Every time a tape cartridge is loaded, the media information is read from the tape
media and saved in drive-resident memory. After being loaded in drive memory, a
read-invalid state is written in the tape-resident RFID. The tape-resident media
information is marked open, read-invalid because it does not reflect results of activity
in the current mount session. All subsequent media information accesses during the
current mount session are saved in the drive-resident information. If no writes are
performed to the cartridge, the RFID remains in the read-invalid state meaning the
1-14 StorageTek T10000 Tape Drive Operator's Guide
Invalid media information might be suspected if you
Note:
observe poor performance on a specific tape cartridge.
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