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Addressing data in the storage

The hard disk drive stores the information in fixed portions, which are called sectors. The sector is the smallest portion of the data that has a unique address and location on a magnetic disk. The exchange of information with the HDD presupposes the address indication as a command parameter. Linear addressing used in hard drives was given the name LBA. On receiving a command the hard drive transmits LBA address to the physical address of the sector, i.e. the number of the cylinder, the head and the sector (CHS).

Before ATA/ATAPI-6 version appeared, the 28-bit number was used for addressing of sectors that limited the maximum capacity of the hard drive to 128 Gb. In new versions of the standard the commands with 48-bit LBA value appeared that has increased the maximum possible capacity of the hard drive to 128 PiB for standard sector size (512 bytes).