What is the Hard Disk Drive?
The primary computer storage medium, which is made of one or more aluminum or glass platters, and coated with a ferromagnetic material. Most hard disks use fixed platters that are permanently sealed in the drive. Hard disks provide fast retrieval because they rotate constantly at high speed, from 4,200 to 15,000 RPM.
ATA, SATA and SCSI Hard Drives.
Most desktop hard disks are IDE (ATAPI/EIDE), whereas SCSI drives are traditionally found on servers and high-performance workstations. The SCSI advantage, over IDE, is that seven to 15 devices can be attached to the same controller board, which uses only one slot in the PC. A serial version of the ATA (IDE) interface, (SATA) provides a point-to-point channel between motherboard and drive rather than the Parallel ATA (PATA) master-slave architecture that supports two drives on the same cable. Serial ATA (SATA) transfers data in a half-duplex channel at 1.5 Gbps (150 MBps) in one direction. With SATA II, introduced in 2003, speed was increased to 3 Gbps (300 MBps).
When was the hard drive made?
IBM introduced the RAMAC hard disk in the mid 1950s. Its platters held only a few hundred thousand bytes and were a foot in diameter. In the 1980s, desktop hard disks started at 5MB using 5.25" platters. Today's disks start at 20GB and use 3.5" or 2.5" platters (the latter in notebooks).
How the data is stored?
Data is stored on the surface of a platter in sectors and tracks. Tracks are concentric circles, and sectors are pie-shaped wedges on a track.
The process of low-level formatting a drive establishes the tracks and sectors on the platter. The starting and ending points of each sector are written onto the platter. This process prepares the drive to hold blocks of bytes. High-level formatting then writes the file-storage structures, like the file-allocation table, into the sectors. This process prepares the drive to hold files.
What hard drives makes and models do we recover data from?
We restore a variety of hard drives from 40MB to over 2TB, such as:
Maxtor | Western Digital | Quantum | IBM | Samsung
Seagate | Hitachi | Fujitsu | Toshiba
SATA | ATA | IDE | SCSI |USB | Laptop