5 skew, 1 cylinder to cylinder skew, 2 track to track skew – IBM C2B 2.25 Brick On Sled carrier 128-pin HPC User Manual
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USER RESPONSIBLE F O R V E R I F Y I N G VERSION A N D COMPLETENESS
O E M F U N C T I O N A L SPECIFICATION ULTRASTAR X P (DFHC) SSA M O D E L S 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.
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.
Notch #
User bytes / logical
block
1
2
3
4
5
6
7
8
9
10
256
42
42
42
40
38
36
36
36
36
32
512
28
28
27
26
25
24
24
23
22
21
520
26
26
26
26
24
24
23
22
22
21
522
26
26
26
25
24
24
23
22
22
20
524
26
26
26
25
24
24
23
22
22
20
528
26
26
26
25
24
24
23
22
22
20
600
24
24
24
23
22
22
21
20
20
20
688
22
22
22
21
20
20
20
20
18
18
744
21
21
21
20
20
20
18
18
17
17
Note: Contact an IBM Customer Representative for values at other formatted block lengths.
Source filename=PERFORM
IBM Corporation
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