Seagate 6450, 6451 manual Physical dimensions, Seek time, Multisegmented cache buffer

Medalist Pro 6450/6451 Product Manual, Rev. B 7

1.4 Physical dimensions

The mounting dimensions are shown in Figure 6 on page 23.

Height, max	1.027 inch (26.09 mm)
Width, max	4.025 inches (102.2 mm)
Depth, max	5.787 inches (146.99 mm)
Weight	1.5 lb (0.68 Kg)

1.5 Seek time

Seek value is the interval between the time the actuator begins to move and the time the head has settled over the target track. Seek time is a true statistical average of at least 10,000 measurements of seek time. All measurements are taken under nominal conditions of temperature and voltage with the drive mounted horizontally. The specifications in the table below are defined as follows:

∙Track-to-track seek time is the average of all possible single-track seeks in both directions.

∙Average seek time is measured by executing seeks in both directions between random cylinders.

∙Full-stroke seek time is half the time needed to seek from track 0 to the maximum track and back to track 0.

Track-to-track	Average/typical	Full-stroke	Average
seek time (typ)	seek time	seek time (typ)	latency
2.0 msec seek	9.5 msec read	20.0 msec seek	5.58 msec
2.5 msec read	10.0 msec write	22.0 msec read
3.5 msec write		23.5 msec write

Note. Host overhead varies between systems and cannot be specified. Drive internal overhead is measured by issuing a no-motion seek. Overhead is typically less than 0.5 msec.

1.6 Multisegmented cache buffer

The Medalist Pro ST36450A and ST36451A drives are available with a 512-Kbyte, multisegmented cache buffer that improves performance by reducing access times.

Read look-ahead.The drive uses the read segments to store additional logical sectors, after the last requested sector, into a buffer before the computer requests the additional sectors. The cache buffer stores data