Data Addressing in Storage Devices
The hard disk drive stores the information in fixed portions, which are called sectors. The sector is the smallest part of the data that has a unique address and location on a magnetic disk. The exchange of information with the HDD presupposes the address indicated as a command parameter. Linear addressing used in hard drives was given the name LBA. On receiving a command, the hard disk transmits LBA address to the physical address of the sector, i.e. the number of the cylinder, the head and the sector (CHS).
Before the ATA/ATAPI-6 version appeared, the 28-bit number was used for addressing sectors that limited the maximum capacity of the hard disk to 128 Gb. In new versions of the standard, the commands with a 48-bit LBA value appeared that had increased the maximum possible capacity of the hard drive to 128 PiB for standard sector size (512 bytes).