Data Dictionary - S

S

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  • SATA
  • SCSI
  • SCA
  • SD Card
  • Sector
  • Seek Time
  • Spindle
  • Striping


SATA

Serial ATA. Latest version of ATA that uses 7 wires interface.(instead of the traditional 40 wires parallel IDE/ATA interfaces).

SCSI
small computer system interface. Mainly used in Servers and Macintoshes to connect high performance hard disks.

  • SCSI-1 - An 8-bit (narrow) SCSI bus (25 pins connector) that transfer up to 4 MBps.
  • SCSI-2 - A narrow SCSI (8-bit) that use 50 pins connector.
  • Wide SCSI - A 16-bit SCSI.
  • Fast SCSI - A faster narrow SCSI that transfer up to 10 MBps.
  • Fast Wide SCSI - A 16-bit SCSI that transfer up to 20 MBps.
  • Ultra SCSI - A narrow SCSI that transfer up to 20 MBps.
  • Ultra Wide SCSI - A 16-bit SCSI that transfer up to 40 MBps.
  • Ultra2 SCSI - A narrow SCSI that transfer up to 40 MBps.
  • Wide Ultra2 SCSI: A 16-bit SCSI that transfer up to 80 MBps.

SCA
Single Connector Attachment. The SCA interface was designed for using hot swappable hard disks. SCA interface hard drives connect to a SCSI backplane that provides power, configuration settings, and SCSI termination to the drives.

SD card
Secure Digital Memory card. A type of flash memory card for data storage devices commonly used in portable devices measuring 32mm x 24mm x 2.1mm. New ultra-small generations include miniSD card (21.5mm x 20mm x 1.4mm) and microSD Card (15mm x 11mm x 1mm) which have the same features.

Sector
A smaller unit found in each track of a cylinder disk with magnetic marking and an ID number. Sectors have a sector header and an error correction code (ECC).

Seek Time
The seek time of a hard disk is the amount of time needed by the read/write heads to move from one track to another destinated track.

Switching between tracks requires the actuator to move the r/w head arms physically. The amount of time needed to travel between two tracks depends on the distance.

  • Average Seek Time - an average seek time from one random track or cylinder to any other track. (Typically 8 to 12 ms)
  • Track-to-Track Seek Time - the time needed to seek between adjacent tracks. (Typically 3 ms or less)
  • Full Stroke Seek Time - the time needed to seek from the innermost track to the outermost track. (Typically 20 ms)

Spindle
the axle on which a disk turns.

Striping
storing of data by distributing them into multiple disks in a certain pattern, so as to achieve certain advantages such as speed, volume space or redundancy depending on the striping method.

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