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• If a T9840A/B drive has down level drive firmware, a high-density data
Exceptional MIR Processing
There are instances when the MIR process departs from the normal.
• Write Protect
When the tape cartridge is write protected, neither the MIR nor FIB is rewritten
and statistical information for that mount is not captured. If the tape cartridge is
in a library that logically write protects the tape cartridge, the MIR is updated as
normal on each dismount.
• Major Error/Power Off
If a tape cartridge is mounted and the drive SNO's (should not occur error) or
loses power, the drive memory-resident MIR is not written to the tape media.
Instead after IPL (initial program load), the drive will read the existing MIR on
tape. Special data is saved in EEPROM that will allow the existing MIR to be
updated and rewritten to the media with the valid flag set. Therefore, the MIR will
contain all positioning information up to the last mount and this tape will operate
with mixed performance until EOD is found. T9840A/B/C drives must have the
appropriate drive firmware level to update the MIR after a SNO or power loss (see
"Mixed Media Management" on page
Invalid MIR Correction
Once a tape cartridge has an invalid MIR, some action is required to correct it. An
invalid MIR can be corrected in several ways using the drive model that created the
cartridge (for example: a T9840A/B formatted cartridge in a T9840A/B drive or a
T9840C formatted cartridge in a T9840C drive).
1. Reading to the end of existing data (EOD) creates a complete and valid MIR. This
is done at normal read speeds and could take up to 45 minutes, for a full 9840 tape
cartridge.
2. Appending to the tape cartridge will also create a valid MIR, although a slow
speed read must first be done to the end of existing user data.
3. The Drive Operation Menu (offline) "Rebuild MIR" utility will sequentially read
from block ID 0 to the EOD. The MIR will be complete and valid when the tape
cartridge is unloaded (see
4. The Drive Operation Menu (offline) "Make Data Tape" utility will reformat the
tape cartridge with a valid MIR. However, all previous data will be lost (see
"Reformat a Cartridge" on page
The memory-resident MIR is always rebuilt to the last block read, on-the-fly, during
normal read/write functions. When the partially rebuilt memory-resident MIR is
written to the tape during the download process, the invalid flag is reset because the
MIR is now partially valid. This can result in seemingly conflicting performance from
a single tape.
Notes:
December 2012
cartridge would be considered as a blank tape cartridge. A low-density data
cartridge would lose statistical data stored in the FIB during a previous mount
into a T9840C drive.
24).
"Build the MIR" on page
67).
Mixed Media Management
68).
Overview 29
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