ICT - Storage Devices and Media

Term 2 - Week 1

A Storage Media

A hardware device that can store data examples:

• Magnetic tape

• CD

• Pen Drive

• Hard Drive

• SSD

A storage device

A hardware device that reads/writes data and stores it in the storage media. Example:

* CD ROM

The three main types of storages

• Magnetic

• Optical

• Solid state

Data transfer rate

The time is takes a storage device to put data (write) to the storage media

Data access rate/time

The time it takes storage device to get data (read) on a storage device

Latency

The time it takes the storage device to a read/write on a storage media simultaneously. The programs like MS Word is an example of this

Magnetic HDD

Cost: Medium

Capacity: High

Durability: Medium

Reliability: Medium

Portability: Medium

Speed: Medium

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SSD

Cost: High

Capacity: Medium

Durability: High

Reliability: High

Portability: High

Speed: High

Optical Media

Cost: Very Low

Capacity: Very Low

Durability: Medium

Reliability: Low

Portability: Very High

Speed: Slow

MAGNETIC TAPE DRIVES definition

• Coated plastic in a magnetic layer (iron oxide)

• Data is written to the tape using a read/write head in a serial sequence and is read in serial order

MAGNETIC TAPE DRIVES uses

• Batch processing applications like bills

• Backup for a large amount of data

• Archiving large amounts of data

MAGNETIC TAPE DRIVES + & -

Advantage

• Inexpensive

• Don’t damage easily

• Huge data capacity

• Data transfer rate fast

Disadvantage

• Data access time is slow

• More than one tape is needed to update the master

• They are affected by magnetic fields

HARD DISK DRIVES (HDD) definition

• Platter is made up of glass or aluminium and coated in iron oxide.

• An actuator triggers the arm to move the head to read/write data on the platter

• Data on the platter is stored in tracks, tracks are grouped on sectors

HARD DISK DRIVES (HDD) uses

• Store operating system

• Store application software

• Used in real-time systems like robots

• Used in file servers

HARD DISK DRIVES (HDD) + & -

Advantage

• Fast data transfer rate and fast access time to data

• Large memory capacity

Disadvantage

• Can be easily damaged from incorrect shutdown

• Many moving parts can affect reliability

• Read/write can be noisy because of the moving parts

OPTICAL MEDIA (CD & DVD) definition

• CD & DVD are Optical Media that are read/written from Optical Storage Media

• Uses a red laser light to burn data onto the surface of the disk

• DVD uses dual-layering.

• A disc that is “RW” means you can erase and then reuse the rewritable disc by burning data into it again.

• A disk that is only R means we can burn data to it only once. For example CD-R, DVD-RW

• A disk that has only ROM to it means we cannot write any data onto it. We can only read the data on it. Example: DVD-ROM

OPTICAL MEDIA (CD & DVD) uses

CD-R & DVD-R

• Used when recording at home music or films

• Stores data for later use

CD-RW & DVD-RW

• Used to record television program (can be done over and over again)

• Used in CCTV system

• Used for backup

OPTICAL MEDIA (CD & DVD) + & -

Advantage

• Cheaper medium than RW

• Behaves like ROM

• Can be written more than once

• Can use different file formats

• More useful than R optical drives

Disadvantage

• Can only be recorded once

• Not all devices can read –R

• It is expensive

• Possible to accidentally override data on the media.

OPTICAL MEDIA (Blu-ray Disk) definition

• Uses a Blu-ray optical storage device to read/write data to disc that uses a blue laser to burn data to disc.

• Stores up to 5 times more data than a normal DVD

• Comes with an automatic encryption which helps to prevent data

• Data transfer is 36Mbps compare to DVD which is 10Mbps

• A dual layer Blu-ray can store up to 50GB (20hrs) of HD movie

OPTICAL MEDIA (Blu-ray Disk) uses

• Home video consoles

• Storing and playing back high definition movies

• Used for storage or backup of hard disk drives

• Camcorders use it to record and store movies

OPTICAL MEDIA (Blu-ray Disk) +& -

Advantage

• Very large storage capacity

• Very fast data transfer

• Greater data access speed than most optical devices

• Comes with automatic secure encryption which helps prevent privacy and copyright infringement

Disadvantage

• Relatively expensive technology and disc

• Encryption problems

• Introduction of HD DVD players has reduce the demand for Blu-ray

Solid State Drive (SSD) do not use?

• Actuators

• No magnetic or moving parts, removing latency

•Flash memory or flash drives are most used type of SSD

•NAND is a type of flash memory that reduces erase and write times lower than hard drive, and requires less chip area per cell, which allows for more storage density and lower cost

How is data stored on SSD drives?

• Data is stored by controlling the movements of electrons within  NAND chips. The positive charge on the control gate attracts the electrons from the channel into the floating gate, where they become trapped by the oxide layer that surrounds the floating gate

• Data will be used whether or not the flash device has power, making the SSD non-volatile and rewritable

• SSD must be used once a year

HDD vs SSD

__**HDD**__

Speed: slower

Lifespan: longer

Cost: cheaper

Mechanics:

Durability: fragile

Best for: storing extra data ex. movies, photos, documents

__**SSD**__

Speed: slower

Lifespan: longer

Cost: cheaper

Mechanics:

Durability: fragile

Best for: storing extra data ex. movies, photos, documents

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Solid State Drive (SSD) uses

Can be used to perform the same functions as HDD including running applications and operating systems. They store files also. Mostly used in modern laptops and smart devices like phones and tablets

Solid State Drive (SSD) +

• More reliable

• Have much faster speed

• Low power consumption

• Cooler than HDD

• Faster data access rate

• Faster data transfer rate

Solid State Drive (SSD) -

Most SSD can accept write up to 20GB per day over a 3 year period (SSD Endurance). It means, services that need more write capacity like servers and cloud storage are not recommended to use SSD

Pen Drive (USB Flash Drive, Memory Stick)1.

Connect to the computer through USB port.

Used for smaller backups and transfer of files. Note: All solid state devices are flash drives

Can be used as a security device to prevent software piracy (Dongle)

Pen Drive (USB Flash Drive, Memory Stick)2.

• Very compact and portable

• Very robust (strong)

• Does not require additional software to work on devices

• They are not effected by magnetic field

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Pen Drive (USB Flash Drive, Memory Stick)3.

• Cannot write protect the files on the drive

• Easy to lose

• Incorrect removal from a computer can cause a read/write error which can corrupt data on the drive

**Memory Cards +**

• SD cards – very small with high capacity. Mostly used in portable devices like phones and digital video recorders. Example MicroSD

• XD cards - design for digital cameras. Some are just card readers used with MicroSD

• CFast cards – used with high ends digital cameras. Does not need battery to access files

• Memory cards are used to store smart devices