Cache memory
The amount of internal hard drive memory. This memory is an intermediate link between the high-speed computer RAM and the relatively slow mechanics responsible for reading and writing information on disk platters. In particular, the buffer is used to store the most frequently requested data from the disk — thus, the access time to them is reduced.
Technically, the size of the buffer affects the speed of the hard drive — the larger the buffer, the faster the drive. However, this influence is rather insignificant, and at the level of human perception, a significant difference in performance is noticeable only when the buffer size of the two drives differs many times — for example,
8 MB and
64 MB.
Average search time
The time it takes for the hard disk mechanics to find random requested data to read. For each specific case, the search time is different, as it depends on the location of the data on the surface of the disk and the position of the read head, therefore, the average value is indicated in the characteristics of hard drives. The lower the average seek time, the faster the disk works, all other things being equal.
Power source (external)
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USB port. Powering an external hard drive directly through the USB connector used to connect to a computer. The advantage of such disks is that they do not require a separate power supply — thus, they can be used even with laptops in the absence of an electrical outlet. However, it is worth considering that the power of the current supplied through the USB connector may sometimes not be enough to start the disc — especially if the connection is made through a USB hub at the same time as several other devices.
— Thunderbolt. Powered directly through the Thunderbolt connector — the same one used for the main connection. For more information about the connector itself, see “Connection Interfaces”, otherwise this option is completely similar to the USB power supply described above (adjusted for the fact that Thunderbolt does not use hubs).
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Power supply. Power supply of an external drive from a separate unit connected to a standard 220V network. Such drives may have a connection interface other than USB, are free from problems associated with insufficient power supply, but their mobility is limited by the availability of electrical outlets.
