IBM F50 RS/6000 7025 - Manual (Page 62)

Operating in Harsh Environments
The 4-mm tape drive is ideally suited to streaming operations, as opposed to tape
movement operations involving multiple stop/starts and random searches. When the
tape is used for frequent stop and start operations, streaming movement is beneficial
and should be used whenever possible. This can be accomplished by ensuring that
any save or restore operation is the only active operation performed by a device
connected to this SCSI I/O controller.
Any tape that has been used outside the ranges specified in the previous table for an
extended period of time (50 passes in 40 hours of nonstop operation) should not be
used as an archival tape. Exposure to the environment will deteriorate the magnetic
and physical strength of the tape. Do not store important data on a tape that has
been used outside the specified ranges; transfer the data to a new tape for reliable
archiving.
4-mm Data Cartridge Erasure
Most bulk eraser devices do not have the capability to erase 4-mm data cartridges.
To properly erase an 4-mm data cartridge with a bulk eraser device, the erasure
rating must be at least 2000 oersted.
The 4-mm tape drive erases residual data before writing new data on the data tape.
Tape Cartridge Data Capacity
The 4-mm tape cartridge capacity is defined as the amount of data that can be
stored on the cartridge. The following variables affect the amount of data that can be
stored on a tape cartridge:
Size of the data file
Number of file marks per file
Compatibility mode (2GB or 4GB)
Media rewrites.
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