Seagate ST157N - 1.3 Access Time Definition and Timing

ST138N
Guaranteed Sectors: 31,059 62,933 107,100
Sectors per Cylinder: 51 103 175
Sectors per Track: 13 26 44
Diagnostic R/W Cylinders: 1 1 1
Bytes per Sector: 1,024 512
256
ST157N
Guaranteed Sectors: 47,047 94,860 161,219
Sectors per Cylinder: n 155
263
Sectors per Track: 13
26
44
Diagnostic R/W Cylinders: 1 1 1
Bytes per Sector: 1,024 512
256
1.3 Access Time Definition and Timing
Access time ts a true statistical average of at least 5000 measurements
of the time It takes to execute the seek speclfted below less overhead.
Overhead ts measured by Issuing a no motion seek from the highest
Logical Block Address (LBA). Seek times are measured by monitoring
the Busy line on the SCSI bus. All measurements assume a block size
of 512 bytes and an ambient temperature of 25° c.
Track-to-track access time Is an average of all possible single track
seekS tn both directions.
Average access time ts measured by executing seek commands from
one random LBA to another.
Maximum (fUll-stroke) access time ts half the time needed to seek from
LBA o to the maximum LBA and back to LBA o.
2 ST125N/138N/157N Product Manual, Rev. C