HDD

Form factor(measures width in inches):

-3.5"

-2.5"

-1.8"

Connection methods:

SATA(card)

PATA(Pins)

"SCSI"-Small computer system interface aka scuzzy

-lots of types

-used mainly for networks

-SCSI-2: 50-pin, molex power

-SCSI-3: 68 PIN. molex power, also has 12 pin aux connector

-SCSI-3 variant: 80 pin

PATA/IDE interface

-40 position connector; 39 pin interface

-Wide thin ribbon cable

IDE drive jumper option

-Maser

-Slave

-Cable select

-You need to know the original jumper setting or imaging will not be successful

SATA-Serial Advanced Technology Attachment

SAS-Serial Attached SCSI

-They look identical

Max Speed ranking

1. SAS

2. SATA

3. SCSI

4. IDE/PATA

Parts of a hard drive

Platter: The name of the disks that hold the data. Round and flat. Magnetic or ceramic. Made of substrate materials and magnetic media coating. Platter one is the top most platter. Platters have two sides with the top side of platter 1 being side 0.

Track: Laser engraved dots on platters. Measured in areal density. Forms multiple concentric circles. All platters have the same number of tracks on a hard drive. Modern hard drive can reach up to 10,000 tracks. Numbering starts at 0 at the outside of the platter.

Sector: The space in between the tracks. 512

Cylinder: A group of tracks in a hard drive that can be accessed at the same time by the read/write head. Cylinder number is referenced more than the track number. Number of cylinders is equal to the number of tracks on a single platter.

The capacity of a disk can be calculated by multiplying cylinders by heads by sectors by sector size.

More platters = a higher risk of failure so it is preferred to try to increase area density of tracks rather than adding more platters.

Sectors

Extra data in sectors:

-ID Info

-Synchronization fields

-Error correcting code(ECC)

Bad Sectors

-Areas of a platter that are damaged. Can be caused by: excessive read/writes

certain viruses

Sudden voltage surges

Identifying bad sectors is called defect mapping

Modern hard drive have reserved sectors that can only be used when a sector fails. This processes is know as Spare Sectoring.

Bad sectors are hard to find with an operating system once they have been identified. The reserve pool is also hidden. PC-3000 is used to find those bad sectors.

File fragmentation: When files are stored across multiple sectors.