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Service Hints & Tips

Document ID: GSMH-39PEDA

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TP 355,360,750,755 - HDD data transfer rate

Applicable to: World-Wide

Service Information:
What are the transfer rates of the ThinkPad 750's 170MB and 340MB harddisks.

2.5 inch 170 million bytes Drive Specifications:

Formatted Capacity 171.9 MBytes
Bytes/Sector 512
Sectors/Track 48(ID)/72(OD)
Cylinders 1575
Number of heads 4
Number of disks 2
Average Seek (ms) 15 ms
Data transfer rate 16.2(ID)/24.0(OD) MBits/sec
Average Latency 7.9 ms
Sector Interleave 1:1
Bus Interface ATA
Buffer 32 KBytes

2.5 inch 340 million bytes Drive Specifications:

Formatted Capacity 344 MBytes
Bytes/Sector 512
Sectors/Track 60(ID)/90(OD)
Cylinders 2263 (User Available)
Number of heads 4
Number of disks 2
Average Seek (ms) 14 ms
Data transfer rate 20(ID)/32(OD) MBits/sec
Average Latency 7.9 ms
Sector Interleave 1:1
Bus Interface ATA
Buffer 32 KBytes


ID = inside diameter (close to the center of the drive)
OD = outside diameter (close to the edge of the drive)

The further away from the center the tracks are, the longer they are.

t = 2 * PI * r

with t = track length
r = distance from center of the disk

In these disk drives we have more sectors per track on the outside than on the inside and consequently more data can be stored per track. Given that the rotational speed of the drive is constant, more date can be transferred from/to the drive when the disk head is positioned at the edge of the disk surface (OD) than near the center of the drive (ID).

	Search Keywords
	Hint Category	Hard Drives
	Date Created	04-09-96
	Last Updated	10-11-98
	Revision Date	10-11-99
	Brand	IBM ThinkPad
	Product Family	ThinkPad 355, ThinkPad 360, ThinkPad 750, ThinkPad 755C/CS
	Machine Type	9545
	Model	Various
	TypeModel
	Retain Tip (if applicable)	N/A
	Reverse Doclinks and Admin Purposes