Throughput; Table 11.Simple Sequential Access Performance; Table 12.Random Access Performance - Hitachi T7K250 - Deskstar - Hard Drive Specifications

4.5.5 Throughput

4.5.5.1 Simple sequential access
The following table illustrates simple sequential access for the three-disk enclosure.
Table 11: Simple Sequential Access performance
Operation
Sequential Read (Zone 0)
Sequential Read (Zone 29)
The above table gives the time required to read a total of 8000h consecutive blocks (16,777,216 bytes) accessed by
128 read commands. Typical and Max values are given by 105% and 110% of T respectively throughout following
performance description.
T = A + B + C + 16,777,216/D + 512/E
where
T = Calculated time (sec)
A = Command process time (Command overhead) (sec)
B = Average seek time (sec)
C = Average latency (sec)
D = Sustained disk-buffer transfer rate (byte/sec)
E = Buffer-host transfer rate (byte/sec)
Note: It is assumed that a host system responds instantaneously and host data transfer is faster than sustained data
rate.
4.5.5.2 Random access
The following table illustrates simple sequential access for three-disk enclosure
Table 12: Random Access Performance
Operation
Random Read
The above table gives the time required to execute a total of 1000h read commands which access a single random
LBA. Typical and Max values are given by 105% and 110% of T respectively throughout following performance
description.
T = 4096(A + B + C+ 512/D + 512/E)
where
T = Calculated time (sec)
A = Command process time (Command overhead) (sec)
B = Average seek time (sec)
C = Latency
D = Average sustained disk-buffer transfer rate (byte/s)
Typical (sec)
0.28
0.55
Typical (sec) Max (sec)
54.6 57.2
Deskstar T7K250 Hard Disk Drive Specification
Max (sec)
0.29
0.58
(READ)
19
(READ)