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• If a T9840C or T9840A/B written data cartridge has an invalid MIR, its
T9840C tape Drive Loaded With a T9840D Data Cartridge
The T9840C drive will not be able to read the MIR written by a T9840D drive.
Because it was written by a T9840D there will be no T9840A/B MIR. The T9840C
drive will read the Format Identity Burst (FIB) written by the T9840D tape drive.
Since the T9840D written data cannot be read by the T9840C tape drive, the only
available drive actions are: 1) unload the data cartridge or 2) reclaim the data
cartridge.
If the data cartridge is reclaimed, the T9840C drive will include the statistical
information from the T9840D FIB when it writes the T9840C MIR and FIB.
T9840C Tape Drive Loaded With a T9840A/B Data Cartridge
When a data cartridge is loaded into a T9840C, the drive first looks for a MIR at the
high-density MIR designated location, and will not find a MIR if the data cartridge is
in low-density data format. The high-density MIR location will be blank if it is the
first time the low-density data cartridge is loaded into a T9840C drive. This causes
the drive to look at the low-density MIR designated location, where it finds a MIR
and reads it into drive memory (invalid flag is not set).
The T9840C drive uses the memory-resident MIR for user data pointers for read-only
functions. During the first mount session, the drive captures statistical counters from
the MIR into a memory area called the Format Identity Burst (FIB), and continues to
build it with drive activity.
During the unload routine, the T9840C drive writes the FIB to the high-density MIR
designated tape location. The tape-resident, low density MIR remains intact and
valid.
Notes:
• The T9840C drive identifies the tape cartridge as low-density data format,
• The T9840C tape drive cannot cause nor correct an invalid MIR on a low-
• If a low-density data cartridge MIR is invalid, it is not read into the T9840C
December 2012
contents cannot be read into the T9840D drive's memory and the user data
pointer information will be unavailable. This causes a performance
degradation.
Note – The T9840C drive identifies the tape cartridge as high-
density data format, and Ready H (high-density) appears in the
T9840C operator panel display.
Note – The FIB is written in a special format which can also be
read by T9840A/B drives with the appropriate drive firmware
level.
which results in the display of Ready L (low-density) on the T9840C operator
panel.
density data cartridge. A low-density MIR can only become invalid during a
mount on a T9840A/B tape drive.
drive memory, and not available for user data pointer information. Therefore,
T9840C performance for a low-density data cartridge with an invalid MIR is
degraded.
Mixed Media Management
Overview 27
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