Different Types of Hard Disk Drive

It is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surface.  

Types of HDD :

1. IDE : Integrated Drive Electronics. IDE drives are also known as PATA drives( Parallel advance technology attachment )
2. SATA : Serial advance technology attachment 
3. SCSI : Small Computer System Interface. SCSI is pronounced as scuzzy.
4. SAS : Serial Attached SCSI

DE / PATA (Integrated Drive Electronics Drive / Parallel Advance Technology Attachment Drive)

• IDE/PATA Drives have usually 40 pins.
• IDE/PATA Drives offer 133 MB/sec transfer rate.
• It sends 8 bit data at a time. 
• PATA Cables are used to connect PATA HDD. Two drives can be connected in a single pata cable. One as master and other as slave. The configuration of master and slave is done by different combination of jumpers in the hdd.

SATA (Serial Advance Technology Attachment Drive)

• SATA Drives have usually 7 pins, 4 pins in pair of two for sending and receiving data and rest 3 pins are grounded.
• SATA Drives offers generally 300MB/sec transfer rate.
• It sends data bit by bit.
• SATA Cables are used to connect SATA HDD. Only one drive can be connected in a single sata cable.

SCSI (Small Computer System Interface Drive)

• SCSI Drives have usually 50 to 68 pins.
• SCSI Drive offers generally 640MB/sec transfer rate.
• This drives are hot swappable. 
• SCSI cables are used to connect SCSI HDD. Maximum of 16 drives can be connected in a single scsi cable. Each hdd have a 8 bytes hexadecimal code known as WWN (worldwide name) for its identification in the cable.

SAS(Serial Attached SCSI Drive) 

• SAS Drives generally offers 805 MB/sec transfer rate. 
• This drives are hot swappable. 
• SAS Cables are used to connect SAS Drives. Maximum of 128 drives can be connected in a single sas cable.