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Mixed Media Management
• Since a T9840C tape drive cannot correct nor rebuild a low-density data
On subsequent mounts, the T9840C drive first sees the tape-resident FIB, identifies
the tape cartridge as low-density, and reads the low-density MIR into drive memory.
At dismount, the T9840C updates the tape-resident FIB with cumulative data,
including newer statistical data from the MIR, if the cartridge had been loaded into a
T9840A/B drive since the last mount in a T9840C drive.
T9840A/B Tape Drives
When a high-density data cartridge is loaded into a T9840A/B drive with appropriate
level firmware, the drive looks for a low-density MIR at the default location but finds
a Format Identity Burst (FIB), which identifies the cartridge as formatted in a high-
density. Because the T9840A/B drive cannot read nor write higher-density data,
subsequent normal read/write attempts will fail unless the cartridge is being
reclaimed.
A T9840A/B drive cannot update statistical data, such as the mount/dismount count
in the FIB. Therefore, cumulative statistical data will not include mounts into a
T9840A/B drive as long as the tape cartridge is in high-density format.
The tape cartridge could be deliberately over-written in low-density data format from
the beginning-of-tape point, or reformatted to low-density data format by the offline
Drive Operation, Make Data Tape submenu. Either case over-writes the FIB with a
low-density MIR, and erases the high-density MIR. Such a reformatted data cartridge
is no longer identifiable as a high-density data cartridge, but does include the
statistical data read from the FIB.
When a low-density data cartridge with a tape-resident FIB (created by a T9840C or
T9840D drive) is loaded into a T9840A/B drive with appropriate level firmware, the
MIR is read into drive memory and an invalid flag is written to the tape-resident
MIR. During the unload routine, the T9840A/B drive compares statistical data in the
tape-resident MIR with statistical data in the tape-resident FIB, and uses the latest
data to calculate the statistical data update into the new tape-resident MIR.
Notes:
• The T9840A/B drive shows Ready H on the operator panel when a cartridge
• If the last load was into a T9840A/B drive, the tape-resident MIR will contain
• To recognize a high-density data cartridge written by a T9840C or T9840D
28 T9840 URM
cartridge invalid MIR, the only options for increasing performance are:
• Migrate the data to a high-density format cartridge, using a copy utility
with a second T9840C drive.
• Rebuild the MIR with a T9840A/B tape drive.
• Operate with degraded performance.
written by a T9840C or T9840D drive is loaded.
the latest statistical data; whereas, if the last load was into a T9840C or T9840D
drive, the tape-resident FIB contains the latest data.
drive, and to properly handle a low-density data cartridge that has been
previously loaded into a T9840C or T9840D drive, T9840A/B drives must have
the appropriate drive firmware level, see
on page
24.
"Mixed Media Management"
December 2012
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