HDD - Cylinder-Head-Sector (CHS) - Cluster - Block

Sector

• the most common physical sector size is 512 bytes
• in CHS addressing the sector numbers always start at 1 (there is no sector 0)

Track

• are the thin concentric circular strips of sectors
• strictly speaking a track is a given Cylinder-Head combination

Cylinder

• is a division of data in a disk drive, as used in the:
  • Cylinder-Head-Sector (CHS) Addressing Mode of a Fixed Block Architecture disk
  • Cylinder-Head-Record (CHR) Addressing Mode of a CKD disk
• the concept is concentric, hollow, cylindrical slices through the physical disks (platters)

Header

• a device that reads and writes data in a hard drive

Cluster

• usually a cluster is a group of sectors

Block

• usually a block is a group of clusters