MEASURING DRIVE PERFORMANCE
1. AVERAGE ACCESS TIME
•In storage devices, average acces time (or seek
time) is thetime required for a read/write head to
move to a spot on the storage medium.
•For storage devices, access time is measured in
miliseconds (ms), or thousandths of a second. In
memory, access time is measured in nanoseconds
(ns), or one-bilionths of a second.
•Diskete drives ofer an average access time of 100
ms. Hard drives are faster, usualy between 6 – 12
2. FILE COMPRESSION
•File compression technologyshrinks files so they take
up less disk space.
•Using a compression utility, you can shrink multiple
files into a single archive file.
•Utilities such as Windows’ DriveSpace enable you to
compress the entire contents of yourhard disk.
3. DATA-TRANSFER RATE
•Data-transfer rate (or throughput) measures the time
required for data to travel from one device to another.
•If a device transfers 45,000 bytes per second, its data-
transfer rate is 45 KBps.
•Hard disks ofer the fastest data-transfer rates of any
4. DRIVE-INTERFACE STANDARDS
•Al PCs use a disk controler as an interface between
a disk drive and the CPU. The two most common
interface standards are EIDE and SCSI.
•EIDE has evolved over the years and has several
variants, al of which have diferent names.
•SCSI is a faster, more flexible drive-interface
standard found in high-performance computers.