Factors Affecting Hard Disk Performance

If a hard disk develops a defect or a read/write head encounters an obstacle, such as a dust or smoke particle, the head bounces on the disk surface, preventing the computer from reading or writing data to one more sectors of the disk. Hard disks can absorb minor jostling without suffering damage, but a major jolt such as one caused by dropping the computer while the drive is running could cause a head crash to occur. Head crashes are one of the causes of bad sectors areas of the disk that have become damaged and that can no longer reliably hold data. If you see an on-screen message indicating that a disk has bad sector, try to copy the data off the disk and don’t use it to store new data. A storage device’s most important performance characteristic is the speed at which it retrieves desired data. The amount of time it takes for the device to begin reading data is its access time. For disk drives, the access time includes the seek time, the time it takes the read/write head to locate the data before reading begins. Positioning performance refers to how quickly the drive positions the read/write head to begin transferring data and is measured by seek time.