Hitachi 7K250 Specifications - Page 33
Throughput
UPC - 000004558972
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4.4.5 Throughput 4.4.5.1 Simple sequential access The following table illustrates simple sequential access for the three-disk enclosure. Table 12: Simple Sequential Access performance Operation Sequential Read (Zone 0) Sequential Read (Zone 29) Typical (sec) 0.3 0.61 Max (sec) 0.32 0.64 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. where T = A + B + C + 16,777,216/D + 512/E (READ) 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. 4.4.5.2 Random access The following table illustrates simple sequential access for three-disk enclosure. Table 13: Random Access performance Table 14: Random Access Performance Operation Random Read Typical (sec) 55.5 Max (sec) 58.1 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) (READ) where T = Calculated time (sec) A = Command process time (Command overhead) (sec) Deskstar 7K250 Hard Disk Drive Specification 19