SCSI (Small Computer System Interface) is the multipurpose interface for connection of peripherals. It contains the full-function controls and is not oriented to any concrete type of devices. Basically, it is used in expensive server solutions. SCSI is especially effective in the implementation of RAID technology. The main advantage of SCSI is that at the very interface creation the ample opportunities have already been included in its specification, e.g. batch execution of commands, out-of-processor (DMA) data transfer, parity check, an automatic speeds selection, etc. that allowed to orient equipment, drivers, and operating systems to them from the very beginning. As for the ATA standard, at the moment of its birth, it was a rather primitive interface aimed at maximum simplicity and cheapness. However, the hardware implementation of ATA has undergone a number of serious changes, while in SCSI basically the transfer rate and the channel width were increased. Modern ATA standard concedes SCSI in the number of devices connected to one and the same cable and in maximum speed of data transfer via the interface only. Other ATA key parameters are not worse than corresponding SCSI ones.