Disk Basics

Hard Disk Drive

  • cylinder
    • the tracks of disk platters that has same diameter
    • a 3d structure looks like a cylinder without top and bottom
  • sector
    • the sectors of disk patters
    • looks like a cut cake
  • head
    • basic read/write device

Solid-State Drive



Creating some logical regions on a drive to manage it.

The partition information is stored in a partition table.

MBR (Master Boot Record)

MBR - Wikipedia

The traditional partition table that can be applied to most PCs that use BIOS.

  • supports 32bit and 64bit systems
  • supports limited number of (primary) partitions
  • cannot (officially) support drives larger than 2T due to the way it addresses space

See the tables in wikipedia for the details about structures.

MBR Partitions

  • Primary partitions
    • at most 4
  • Extended partitions
    • uses “space” of a primary partition
  • Logical partitions
    • created in extended partitions
    • does not count as a primary partition, can have more than 4

GPT (GUID Partition Table)

GPT - Wikipedia

A partition table for UEFI devices (instead of BIOS)

  • supports drives larger than 2T
  • limited backward compatibility (for MBR)

Read the table in wikipedia about “Operating-system support”