IBM Enterprise Server S80, Руководство пользователя

Страница: 53 / 282

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 deteriorates 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:
v
Size of the data file
v
Number of file marks per file
v
Compatibility mode (2GB or 4GB)
v
Media rewrites.
Chapter 2. Using the System
35