Hard Disk by Marshall Brain
There are currently 3 connections for a hard disk. IDE (or ATA) SCSI and
Serial ATA. The most common is the IDE interface. This provides an 80 pin
connection to most standard motherboards and you can't normally go wrong
buying an IDE drive for your machine. SCSI connections often require extra
hardware unless its built into your motherboard. SCSI hard disks are often
faster but more expensive than there IDE counterparts. The final type is
the newest type. Serial ATA does away with parallel data transfer which
has its problem of large wires and electrical interference. The Serial ATA
standard is more reliable and uses smaller un-obtrusive wires. Smaller
wires also means better air flow for your case.
How does data Store?
On a harddisk, data is stored in the magnetic coating of the disk. The so
called head, held by an actor arm, is used to write and read data. This
disk rotates with a constant turn time, measured in revolutions per minute
(rpm). Data is organized on a disk in cylinders, tracks and sectors.
Cylinders are concentric tracks on the surface of the disk. A track is
divided into sectors. A harddisk has a head on each side of a disk.
Nowadays, the actuator arm is moved by a servo-motor (not a step-motor
which needs more time while swinging in after moving over the desired
track). All harddisks have reserved sectors, which are used automatically
by the drive logic if there is a defect in the media.
A file system is the way in which your computer stores data on the hard
disk. The most common file systems are FAT16 for older computers, FAT32
and NTFS. FAT stands for File Allocation Table. NTFS stands for NT File
System. Both have advantages and disadvantages. FAT16 was a very limited
file system in the way that it would store data very in-efficiently, every
file would take up a minimum of 32Kb in space as this was the minimum
cluster size in a FAT16 system. Also it was only capable of using hard
disks upto 2Gb in size. FAT32 solved this problem by reducing the cluster
size to 4kb which saved a lot of wasted space and also allowed disk sizes
up to 2 Terra bytes. NTFS is believed to be a far greater file systems
than any of the FAT's. The cluster sizes can be altered to anything as low
as 512bytes which means almost no wasted space on the hard disk. The
maximum disk size is a unbelievable 18.5 x 10นบ bytes, which is very big
!!!. NTFS also has added security for file loss.
Speed of Drive
The speed of a drive is measured in milliseconds so 10ms is faster than
12ms the RPM (revs per minute) is also important for speed. The higher
number of RPM's the better, also any cache if possible, all of this
improves the speed of the drive under some circumstances your hard drive
does get some serious hammering so its very important to pick the right