IBM DARA-206000 Hard Drive Specifications - Page 21

3.3.1 Command Processing Command overhead time is defined as the total time from when the command is received by the drive to the start of motion of the actuator. 3.3.2 Average Seek Time (Including Settling) Command Type Typical Read 12 msec Write 14 msec (except DARA-225000) 13 msec (DARA-225000) Figure 6. Mechanical Positioning Performance Max 16 msec 17 msec 'Typical' and 'Max' are given throughout the performance specification by; Typical Max Average of the drive population tested at nominal environmental and voltage conditions. Maximum value measured on any one drive over the full range of the environmental and voltage conditions. (See section on Environment and D.C. Power Requirements.) The seek time is measured from the start of motion of the actuator to the start of a reliable read or write operation. Reliable read or write implies that error correction/recovery is not employed to correct for arrival problems. The Average Seek Time is measured as the weighted average of all possible seek combinations. Weighted Average = max ∑ ( max + 1 − n) (Tn.in + Tn.out) n= 1 ( max + 1) ( max) Where: max = Maximum seek length n = Seek length (1 to max) Tn.in = Inward measured seek time for an n track seek Tn.out = Outward measured seek time for an n track seek 3.3.3 Single Track Seek Time Function Read Write Figure 7. Single Track Seek Time Typical 2.5 msec 3.0 msec Max 4.0 msec 4.5 msec The single track seek time includes settling time but does not include command overhead. Single track seek is measured as the average of one (1) single track seek from every track in both directions (inward and outward). Drive Characteristics 11