PPT Slide
Disk performance parameters
- Seek time
- time to move disk arm to a track
- S = m x n + s (m is a constant per disk, number of tracks transversed, s startup time)
- Rotational delay
- waiting time for a given sector align with the head
- disks: =~ 3,600 rpm, average = 8.3 msec
- diskettes= 300-600 rpm, average = 100 and 200 msec
- Access time = seek + rotational delay
- Transfer time
- time to spin record by the head (to read or write)
- T = b/ rN (b is number of bytes to be transferred, r rotation speed rpm/sec, N number of bytes on a track)