Skew; Cylinder To Cylinder Skew; Track To Track Skew - IBM C1B 1.12 Brick On Sled Carrier 128-pin HPC Specification Sheet

O E M FUNCTIONAL SPECIFICATION ULTRASTAR XP (DFHC) SSA MODELS 1.12/2.25 GB - 1.0" H I G H
The full benefit of out of order transfers in only achieved if OOTI is also set. Read data is transferred on the
interface in the same order as it was read from the media.

3.5 Skew

3.5.1 Cylinder to Cylinder Skew

Cylinder skew is the sum of the sectors required for physically moving the heads (csms), which is a function
of the formatted block length and recording density (notch #), and reassign allowance sectors (ras = 3) used
to maintain optimum performance over the normal life of the drive.
Note: The values in the Mode Page 3 'Cylinder Skew Factor' are notch specific non-synchronized spindle
mode values. The value for notch 1 is returned when the Active Notch is set to 0.
User bytes / logical 1
block
256 42
512 28
520 26
522 26
524 26
528 26
600 24
688 22
744 21
Note: Contact an IBM Customer Representative for values at other formatted block lengths.
Table 8. Optimal Cylinder Skew for several block lengths
In order to increase the likelihood that equivalent LBA's on two or more devices are located at the same
relative physical position when the devices are used in a synchronized spindle mode, cylinder skew is calcu-
lated differently. The cylinder skew calculations do not take into account known defective sites. To prohibit
revolutions from being missed on cylinder crossings by drives formatted while in a synchronized spindle
mode, an extra allowance for 6 defects is added that is not added when optimally formatted in a non-
synchronized mode.

3.5.2 Track to Track Skew

Note: The values in the SCSI Mode Page 3 'Track Skew Factor' are notch specific values. The value for
notch 1 is returned when the Active Notch is set to 0.
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USER RESPONSIBLE F O R VERIFYING VERSION A N D COMPLETENESS
2 3 4
42 42 40
28 27 26
26 26 26
26 26 25
26 26 25
26 26 25
24 24 23
22 22 21
21 21 20
IBM Corporation
Notch #
5 6 7
38 36 36
25 24 24
24 24 23
24 24 23
24 24 23
24 24 23
22 22 21
20 20 20
20 20 18
8 9 10
36 36 32
23 22 21
22 22 21
22 22 20
22 22 20
22 22 20
20 20 20
20 18 18
18 17 17
Source filename=PERFORM