An Acronym for Logical Block Addressing

LBA is a addressing scheme for HardDisk sectors that uses a single number starting at 0. It supersedes the classic CHS addressing.

LBA addresses can be 28 bit or 48 bit wide.

With the common 512 byte sector size, 28 bits are somewhat limiting:

512 byte sectors = 2⁹ Bytes

2²⁸ * 2⁹ Bytes = 2³⁷ Bytes = 137,438,953,472 Bytes

That is 128GiB:

1 GiB = 2³⁰ Bytes

2³⁷ Bytes / 2³⁰ = 2⁷ GiB = 128 GiB

Disk manufacturers actually use GB, btw:

1 GB = 10⁹ Bytes

2³⁷ Bytes / 10⁹ = 137.43 GB

This is the reason for older OperatingSystems or controllers without 48 bit LBA support failing to detect a large contemporary disk correctly.

48 bit LBA offers much larger disks:

2⁴⁸ * 2⁹ Bytes / 2³⁰ = 2²⁷ GiB = 134,217,728 GiB = 128 EB

Part of CategoryHardware