4.4.5 Throughput
4.4.5.1 Simple sequential access
The following figure illustrates the case of the three-disk enclosure.
0.640.61Sequential Read (Zone 26)
0.340.32Sequential Read (Zone 0)
Max (sec)Typical (sec)Operation
Figure 13. Simple Sequential Access performance
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.
Note: It is assumed that a host system responds instantaneously and host data transfer is faster than
sustained data rate.
T = A + B + C + 16,777,216/D + 512/E (READ)
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)
4.4.5.2 Random access
The following figure illustrates the case of the three-disk enclosure.
59.056.3Random Read
Max (sec)Typical (sec)Operation
Figure 14. Random Access Performance
The above table gives the time required to execute a total of 1000h read commands which access a
single random LBA.
T = 4096 (A + B + C + 512/D + 512/E) (READ)
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)
E = Buffer-host transfer rate (byte/s)
4.4.6 Operating modes
4.4.6.1 Operating mode descriptions
Deskstar 180GXP hard disk drive specifications
16
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