Hard disks are non-volatile storage devices which digitally store encoded data inside of sealed cases to keep out dust particles.  Dust can affect the readability or even a loss of stored data.  Inside the sealed case, the rapidly rotating disks with magnetic surface are read by a magnetic head.  Each hard disk drive has a specific interface, e.g. PATA (IDE), SATA, SAS, SCSI (often on servers), FC with which it connects to a host adapter.  Capacities of HDDs are indicated in terabytes, gigabytes, or for older HDDs, in megabytes.  End-of life hard disk drives often have removable media.

Defective drives may need either of the following parts to be replaced:  Platter, spindle, head, actuator, actuator arm, actuator axis, power connector, jumper block, IDE connector.

Telios Tech can rapidly and correctly diagnose the root cause of our customers’ HDD problems, recommend a solution and either repair the defects in a cost-effective manner or offer the customers replacement HDDs at competitive prices.
 
Name Explanation
Units
Formatted size
 Total size of formatted disk drive
Megabyte(MB)
Platter Physical disk with magnetic surfaces on either side.  Multiple platters are stacked to create the disk assembly
Track Thin, concentric circular strip on the magnetic disk (platter) surface where data is written
Cylinders Total number of tracks that can be accessed without moving the read/write heads on a platter
Sector
Division of a hard drive platter into a number of slices
Block Intersection of a track and sector on a specific hard drive platter.  The smallest amount of data that can be transferred Typically 512 bytes
Head Each head reads data from and writes data to the magnetic surface of a specific platter
Encoding Method Translation method used to store data for reliable retrieval  
Search time Average access time of magnetic heads Millisecond (ms)
Interface Communication type used: PATA/IDE, SATA, SCSI, SAS, Fibre Channel
Cache
 Total size of buffer Killobite(KB)
RPM Rotational speed of drive motor Revolutions per minute
Form factor
 Physical data for reliable retrieval and width inch
 
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