HP Surestore DLT 80 Tape Drive - Manual (Page 55)

Tape Cartridge Densities and Compression
Density
5-2
Density
Note A tape cartridge can only contain data at one density.
Density, as used on the drive’s front panel, means a combination of native
capacity (the capacity of the tape cartridge without using data
compression) and whether data compression is on or off. The actual
capacity using compression depends on the type of data being stored.
When you load a tape cartridge, the lights on the left side of the front panel
show one of the following:
• For a new tape cartridge, the lights show the default density of the tape.
Compression will be set on if it is available for that cartridge type.
• For a tape cartridge containing data, the lights show the density at
which the data was written and whether it is compressed.
If the drive starts writing data to a blank tape cartridge, it will write at the
default density with compression on. If it appends data to a tape cartridge
that already contains data, the drive will write at the same density as the
existing data.
Changing the Density and Compression for Writing
Caution If you load a tape cartridge that already contains data and then write with
a new density, all the existing data on the tape will be lost. A new density
can only be used when writing from Beginning of Tape (BOT).
• For the DLTtape IV tape cartridges you will usually use with an
HP SureStore DLT 40, you can only choose to have compression on or
off.
• With the HP SureStore DLT 70 and 80, you can choose to write at
20.0 GB density if you wish, so that the tape can be read by an
HP SureStore DLT 40.
• On type III tape cartridges, HP SureStore DLT drives allow you to write
data at a different density from the default. You might want to write at
a different density so that the tape cartridge can be read by a lower
capacity drive.
The possibilities are shown in the tables on the next page. The default
settings when you load a new tape cartridge are shown shaded.
dlt.book Page 2 Monday, February 12, 2001 5:42 PM