IBM TS22 Series, Manual

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To improve system performance, the drive uses a technique that is called speed matching to dynamically adjust its native (uncompressed) data rate to the slower
data rate of a server.
With speed matching, the drive operates at different speeds when it is reading or writing the Ultrium 7 or later cartridge format. Native data rates are shown in the
table.
Table 1. Performance parameters for full height drives
Ultrium Generation Media
Generation 9 media Generation 8 media Generation 7 media
Speed matching data rates (MB/sec) 408 365.0 306.0
385 341.0 287.52
366 318.0 268.56
347 306.4 250.66
325 273.0 231.86
305 249.5 213.06
284 226.0 194.26
263 203.0 175.46
244 180.0 157.67
223 157.5 138.52
203 135.0 120.11
177 112.0 101.46
Table 2. Performance parameters for half height drives
Ultrium Generation Media
Generation 9 media Generation 8 media Generation 7 media
Speed matching data rates (MB/sec) 284 306.4 306.0
263 273.0 287.52
244 249.5 268.56
223 226.0 250.66
203 203.0 231.86
177 180.0 213.06
- 157.5 194.26
- 135.0 175.46
- 112.0 157.67
- - 138.52
- - 120.11
- - 101.46
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 optimized by channel calibration.
System performance is further optimized by a feature that is 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
Capacity scaling enables faster random access to data.
The SET CAPACITY SCSI command enables a customer to capacity scale a data cartridge to enable faster random access. As an example, a customer can capacity
scale a data cartridge to 20% of its normal length that improves the average access time by almost a factor of 5. However, it also reduces the native capacity of the
tape to 1.2 TB.
Encryption
The LTO tape drive supports host Application Managed Encryption (AME), with T10 encryption methods.
Data encryption is supported by LTO Ultrium 4 and later data cartridges only.
The encryption-enabled drive contains the necessary hardware and firmware to encrypt and decrypt host tape application data. Encryption policy and encryption
keys are provided by the host application. A drive digital certificate is installed at manufacturing time. Each drive receives a unique serial number and certificate.
The T10 Application can validate each drive instance by checking the drive's digital certificate.
IBM TS22xx Tape Drives 85