What is LBA in hard disks?

Answer 1

Logical Block Addressing (LBA)

Regular addressing of IDE/ATA drives is done by specifying a cylinder, head and sector address where the data that is required resides. Extended CHS addressing adds a translation step that changes the way the geometry appears in order to break the 504 MiB barrier, but the addressing is still done in terms of cylinder, head and sector numbers (they are just translated one or more times before they get to the actual disk itself).

Answer 2

LBA, in relation to computer hard drives, means Logical Block Addressing. LBA replaces older schemes such as CHS (cylinder-head-sector). CHS was not very useful for newer types of hard drives and storage devices other than hard drives. After all, IDE/ATA/SATA drives use varying sectors per track. Those devices did use translation modes to convert whatever scheme they used into cylinder, head, and sector values, but the usefulness of this was limited. Plus the old schemes had size limits that are considered very small by today's standards.

The current 48-bit LBA scheme can address drives as large as 128 PiB.