The cache memory keeps the data accessing the disk more often to improve overall performance. It is therefore important to have as much as possible ...! The cache size varies from 8 to 32MB per disk drive.
The different speeds of rotation
The speed of rotation of the disk determines the access time is the time that the playhead will need to go to the location of the data. The different speeds are:
5400 rpm (now reserved for laptops, some can provide excellent performance)
7200 rpm (the speed the most prevalent. It is also well integrated into the hard drives for laptops in hard disks for computers fixed)
10 000 rpm (already more scarce it is very popular with gamers who take one or two for the rise in RAID0)
15 000 rpm (restricted servers these drives offer performance out of the ordinary with access time neared 3ms)
The concept is simple: to make multiple hard drives a single virtual hard disk, by multiplying the number of hard drives transfer rates. This solution offers exceptional performance, provided that it takes two (or more) identical hard disk drives.
To connect your hard drive, I refer you to another article where you find everything you need.
There are three types of disks: 5 inches to 3.5 inches and 2.5 inches
Note that 5 inches are no longer manufactured.
The hard disk in the future
The future of hard disk is ... SSD! At least for laptops. This disc is made of flash memory as a USB drive but with more memory, making it completely silent. Access times are extremely limited: 0.1m. Power consumption is much lower than most hard drives. But the number of entries is limited (between 100 000 and 300 000), the exorbitant price and storage capacity still very low.