Storage Device Notes
In general, mass storage technologies are grouped into three broad categories:
- Magnetic Media (Hard Disks and Tapes)
- Non-volatile memory (flash)
- Optical media
Various HDD Forms
Length of the drive
- 3.5"
- 2.5"
- 1.8"
Different types of drives (will mostly be seeing SATA)
"SCSI" - Small Computer System Interface
- AKA Scuzzy
- Lots of different form factors
- Pin based
Some of them use "molex" power
- 40 position connector; 39 pin interface
- IDE Drive jumper options - Master, Slave, Cable select (Note original jumper setting prior to image)
- Standard power connector
- "IDE" - Integrated Drive Electronics (aka PATA)
SATA - Serial Advanced Technology Attachment
SAS - Serial Attached SCSI
They look the same!
Disk Platter - round flat magnetic or ceramic discs in a hard drive that holds the actual data
Made of two materials
- Substrate material
- Magnetic media coating
Disk platter organization
- Each platter has two sides
- A hard drive can have multiple platters
Concentric circles where all the information is stored
- Modern disks contain 10k+ tracks
- Each platter within a hard drive will have the same amount of tracks
A group of tracks in a hard drive that can be accesses at the time time by the read/write head
- Typically we refer to cylinder and not the track number
Number of cylinders (tracks), heads (sides) and sectors (aka CHS) uniquely identify the physical geometry of the storage units on a disk
CHS also yields disk capacity:
- Capacity = Cylinders x Heads x Sectotrs x sector_size
Logical Block Addresses (LBA)
- Odd heads because one is only accessible from one side (top or the bottom)
Why more than one platter?
- More storage!
As more platters are added to the fixed HDD space, the gaps between each disk decreases
- More susceptible to vibrations and platter surface imperfections
The trend has been to decrease the number of platters by increasing the area density on each