Transfer rate is of two kinds: the interface transfer rate and transfer rate media. Transmission speed of the interface – the maximum theoretically achievable data rate of a hard drive from its buffer to the system. Media transfer rate measures how fast data can be moved to the media or with him. The rate of placing on the carrier (ie, write, Write Speed), as a rule, does not equal the speed of obtaining from him (read, Read Speed), and therefore usually separately specified recording speed and reading speed. The higher speed data – the better. Buffer. Another important criterion is the size of the buffer. The buffer (otherwise referred to as cache memory) stores data that are accessed most frequently or data that may be needed user to the next time.
Input / output data from the buffer occurs very quickly, data is transmitted to the system with a maximum interface speed. Thus, the larger the buffer, the greater the volume necessary information is stored in it, the faster the hard drive itself. Hard disk rotational speed. No less important parameter is the rotation speed is the number of spindle revolutions per minute. On this parameter in depend largely on access time and transfer rate. For external hard drives can be found at two speeds: 5400 and 7200 rev / min. Than at higher speeds – the more comfortable and faster to work with the hard drive. Interface.
External hard disk consists of a container for the HDD, which is placed inside the hard drive. Container and connect the hard drive interface, which is called internal. To replace the outdated IDE interface came SATA interface. External HDD drives with IDE interface is almost impossible to find on sale, but they do not, and practical necessity. Thus, most external hard drives have an internal SATA interface. As for the external interface, for the vast majority of external hard drives is USB 2.0.