IBM System Storage TS2230, Руководство по установке, эксплуатации и обслуживанию

Страница: 28 / 141

Table 1-2. Performance Parameters
Ultrium Generation Media
Generation 3 Media Generation 2 Media Generation 1 Media
Speed matching data
rates (MB/sec) 80.0 35.0 20.0
76.1 33.7 19.2
72.3 32.3 18.5
68.4 31.0 17.7
64.6 29.6 16.9
60.7 28.3 16.2
56.8 26.9 15.4
53.0 25.6 14.6
59.2 24.2 13.8
45.3 22.9 13.1
41.5 21.5 12.3
37.6 20.2 11.5
33.8 18.8 10.8
30.0 17.5 10.0
If the server's net (compressed) data rate is between two of the preceding native
data rates, the drive calculates the appropriate data rate at which to operate. Speed
matching dramatically reduces backhitch, the condition that occurs when a tape
stops, reverses, and restarts motion. A backhitch is usually the result of a mismatch
between the data rates of the server and the drive.
Channel Calibration
System performance is further optimized by a feature called channel calibration , in
which the drive automatically customizes each read/write data channel to
compensate for variations in such things as the recording channel's transfer
function, the media, and characteristics of the drive head.
Data cartridge capacity scaling
The SET CAPACITY SCSI command enables a customer to capacity scale a data
cartridge to enable faster random access. As an example, a customer could capacity
scale a data cartridge to 20% of its normal length which improves the average
access time by almost a factor of 5; however, it also reduces the native capacity of
the tape to 80 GB.
Inhibit firmware down-leveling
The drive provides the capability to prevent loading and installing drive microcode
via a Field Microcode Replace (FMR tape) if the firmware level contained in the
FMR tape is older than the code level already installed. This option is controlled
by the host application. No checking will be performed if the firmware level is
loaded via the host interface or the library interface.
1-4
TS2230 Tape Drive Setup, Operator and Service manual