Interface of hard disk

PATA (parallel advance technology attachment)

  • 40 pins data cable connector.
  • Maximum four hard disk can be connected.
  • Single cable can connected two devices.
  • RPM 5400 to 7200 (platter rotation speed).
  • Data transfer speed = 140 to 150 mbps.


  • Older PATA adapters will limit transfer rates according to the slower attached device (debatable)
  • Only ONE device on the PATA cable is able to read/write at one time
  • Limited standard for cable length (up to 18inches/46cm)


  • Low costs
  • Large capacity

SATA (serial advance technology attachment)

  • 7 pin data cable connector.
  • Maximum 4 hard disk device can be connected.
  • Single cable can connect single device.
  • RPM speed up to 100000.
  • Data transfer speed= 150 to 160 mbps.


  • Slower transfer rates compared to SCSI
  • Not supported in older systems without the use of additional components


  • Low costs
  • Large capacity
  • Faster transfer rates compared to ATA (difference is marginal at times though)
  • Smaller cables for better heat dissipation

SCSI (small computer system interface)

  • 50 to 68 pin data cable connector.
  • It needs a SCSI card
  • Connect the hard disk device in chain method.
  • RPM speed up to 15000
  • Data transfer rate speed= 320 mbps


  • Costs
  • Not widely supported
  • Many, many different kinds of SCSI interfaces
  • SCSI drives have a higher RPM, creating more noise and heat


  • Faster
  • Wide range of applications
  • Better scalability and flexibility in Arrays (RAID)
  • Backward compatible with older SCSI devices
  • Better for storing and moving large amounts of data
  • Tailor made for 24/7 operations
  • Reliability
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