Different types of Computer Hard Disk Drive and its Connectors

A hard disk drive also called hard drive, hard disk or disk drive is a device used for storing and retrieving digital data or information. A hard disk is a stack of disk known as the platter. A single hard disk usually consists of several platters and each platter requires two read/write heads, one for each side and is attached to a single access arm. Data are recorded electromagnetically in a concentric circle such as the track on a disk.

A hard disk speed can vary from 4500rpm - 7200rpm for Parallel ATA and 10000rpm to 15000rpm for SCSI drive and Serial Attached SCSI (SAS). Hard drive with 10000rpm to 15000rpm is more expensive than lower rpm drives, this kind of HDD are used primarily on servers that are used for transaction processing databases, internet infrastructure such as email, web server that require intensive data processing and operate continuously. HDD that are running 10,000rpm to 15,000rpm has smaller platters to lessen the power requirements and therefore have lower capacity than desktop computer drives.

• Platter :
  A hard disk platter or the disk is a circular disk in which the magnetic data is stored. A hard disk drive can have several platters that are mounted on the same spindle.


• spindle / spindle motor :
  The spindle motor is responsible for turning the hard disk platters and  must provide stable, reliable and consistent turning , to allow the hard disk to function properly.


• Head :
  Responsible for read - write operation of data from and to the platter

• actuator :
  Used to position the head arms to different tracks on the surface of the platter, actuator is used in changing from track to track the only operation on the hard disk that requires active movement. This mechanism of hard disk must works at extreme speed, with precise accuracy for the data to be read and write accurately on the platter.

Different types of Hard disk drive (HDD)

Parallel Advance Technology Attachment (PATA) drives are also known as Integrated Drive Electronics (IDE) developed by Western Digital under the name Integrated Drive Electronics (IDE)

Small Computer System Interface or SCSI for short and can be pronounce as "skuzzy" are high performance storage drives. SCSI drives are commonly found in servers were real time performance or 24/7 operation is required. SCSI drive are much faster than the standard drive Parallel ATA (PATA) with 5400RPM - 7200RPM access time compared to 10000RPM - 15000RPM for SCSI. Revolution Per Minute "RPM" of hard drives is a measurement of how many complete revolutions a computer's hard drive makes in a single minute. Fast rotation speed of the spindle means high data transfer , the higher the RPM, the faster the data will be accessed

Parallel Advance Technology Attachment (PATA) drives are also known as Integrated Drive Electronics (IDE) with 2.5 inch form factor. Due to its smaller size it is commonly used in notebook PCs, external storage, gaming consoles, and portable video players.

Serial ATA was designed to replace the older parallel ATA (PATA). SATA offers several advantages over the older IDE drive such as reduced cable size reducing from 40 pins in IDE to 7 pins in SATA, native hot swapping and has faster data transfer through higher signaling rates.

The Serial Attached SCSI (SAS) is a new generation serial communication protocol for devices designed to allow for much higher speed data transfers and is compatible with SATA. The serial transmission of data requires fewer connections and eliminates the SCSI bus and still uses the very capable SCSI protocol. SAS uses a mechanically identical data and power connector to standard 3.5-inch SATA1/SATA2 HDDs and many server-oriented SAS RAID controllers are also capable of addressing SATA hard drives. SATA drives can be attached to a SAS drive controller and they will work perfectly because they are compatible but not SAS drive connected to a SATA controller this configuration will not work.