IBM System Storage TS3500, Введение и руководство по планированию

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(EFMT1) records 512 tracks on 8 channels. Enterprise format 2 (EFMT2)
records 896 tracks on 16 channels. Enterprise format 3 (EFMT3) records
1152 tracks on 16 channels. Enterprise format 4 (EFMT4) records 2560
tracks on 32 channels. These logical formats can be divided into multiple
sub-format options, such as segmentation and capacity scaling. For more
information about capacity scaling and segmentation, refer to “Capacity
scaling and segmentation” on page 176. For a complete matrix of read and
write compatability by cartridge and format type, refer to “Mixing media
in drives” on page 37.
Speed matching
When operating in a host environment where the net host data rate is less
than the maximum drive native data rate, 3592 tape drives automatically
perform dynamic speed matching to minimize backhitches. Dynamic speed
matching adjusts the native data rate of the drive as closely as possible to
the net host data rate (after data compressibility has been factored out). A
reduction in backhitches improves system performance.
HRTD The HRTD directory structure, located in 3592 tape drives, allows the drive
to have fast and consistent nominal and average access times for locate
operations.
Channel calibration and on-the-fly adaptive equalization
To gain optimum performance, channel calibration allows the drive to
automatically customize each read and write data channel. The
customization compensates for variations in the recording channel transfer
function, for media characteristics, and for read and write head
characteristics. Initial calibration settings are calculated and stored at the
time of manufacture. For optimum error rate performance, TS1120 and
later tape drives also use on-the-fly adaptive equalization hardware on an
ongoing basis to adjust the read equalization response.
Recursive accumulating backhitchless flush
The TS1120 and later tape drives use an algorithm known as recursive
accumulating backhitchless flush (or non-volatile caching) to increase
effective data rate performance from host servers that force explicit
synchronize operations during write operations.
Backhitchless backspace
Backhitchless backspacing enables some backspace operations to be
virtualized without physical backhitching. If you write and overwrite
multiple trailer labels, this firmware feature provides major performance
improvements. For more information, refer to the appendix about WORM
behavior in the
IBM System Storage 3592 Tape Drive SCSI Reference .
Capacity scaling
If you want to exchange capacity for improved access times, 3592 tape
drives support multiple format options, such as scaling and segmentation
modes. These tape drives can sense and report the scaling state of current
medium by using the SCSI Mode Sense command and specifying Mode
Page X'23'. Capacity scaling is only offered on the JA, JB, and JC media
types. For the exact Mode Select commands and settings necessary to
invoke scaling, refer to the
IBM System Storage TS3500 Tape Library SCSI
Reference .
WORM
The 3592 tape drives support write-once-read-many (WORM) behaviors
and format attributes. Four WORM cartridge types are supported: JW (full
length), JR (short length), JX Extended WORM cartridge (for TS1120,
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IBM System Storage TS3500 Tape Library with ALMS: Introduction and Planning Guide