Storage Flashcards
Secondary storage non volatile- what does this mean
It means that data wont be lost in this type of storage if the system suddenly gets switched off
Give three uses of secondary storage-
Store a document for future use
Store an application, ready to be loaded to the ram when the user opens the application
virtual memory
Define virtual memory-
It is a storage space in a computer
which stores programs and instructions until they are needed or being used
Define a motherboard
It is a circuit in the computer with connectors through which other components connect.
What are internal and external storage devices
Internal storage devices are storage devices that are directly connected to a computers motherboard.
External storage devices are storage devices that connect to the the device via interfaces such as ports or adapters on the computers exterior
What are storage devices
Storage devices are used to store data and software which are used in a computer systems.
What is a hard disk drive?
A hard disk drive contains hard disk media and they can provide connection to a devices motherboard either directly or by a wireless adapter such as WIFI or wired connection such as a USB cable
What is a solid state drive
a solid state drive commonly referred to as a flash drive contains flash media. Other wise it is identical to a hard disk drive
Describe how connection can be provided to these drives via wireless adapters such as wifi-
A type of secondary storage known as network attached storage, which contains multiple Hard disk drives and solid state drives, is directly connected to a router via a SATA/IDE cable. A device can wirelessly communicate with that router and access the data and software stored on the NAS so that it can be used by the computer system.
Define optical drives
Optical disk drives contain optical disk media.
define backwards compatibility with an example
The ability to be used with older technology without needing to be specifically adapted. For example a blue ray drive adapted to read blue ray disks can jolly well read DVDs and CDs
define backwards compatibility with an example
The ability to be used with older technology without needing to be specifically adapted. For example a blue ray drive adapted to read blue ray disks can jolly well read DVDs and CDs
Describe hard disk media
Hard disks are made up of many concentric platters. These platters make up a cylinder which spins on a central spindle. It also has an/multiple actuators depending on the type of hard disk which read and write heads are mounted on.
What affects the amount of time taken by the read and write heads to access the data on the disk
the speed at which the disks spin around the spindle
the speed at which the read and write heads are moved across the tracks by the actuator arm.
How do the read and write heads read and write data on the platters
when reading, the R/W heads are able to convert the magnetic field into electric charge and when writing converts the electric charge into a magnetic field.
What is seek time and what is it typically measured in?
Seek time refers to the amount of time taken by the read and write head to locate the area on the disk in which the data to be read is stored.
4 -15 miliseconds
What are spin speeds measured in and their typical values
5400 to 7200 revolutions per minute
Optical media
Describe CDs, DVDs and Blue Ray Disks
Hint: You keep on forgetting one crucial detail about Blue ray disks.
CD disks- Can store up to 700MB worth of data.
Data is written on the CD disks via laser which writes data on the plastic layer of the disk beneath other layers of aluminum and acrylic.
DVD disks- These disks use a red light laser which has a shorter wavelength than the laser used by CDs to write data on the disks and therefore can store more data.
Single sided single layered DVD disks can store up to 4.7 GB and double layered double sided disks can store up to 20 GB worth of data.
Blue ray disks use violet light lasers to write data on the disk which have an even shorter length and can store data at a much higher density than DVDs. 25 GB on single side and 50 GB on double side.
It uses sophisticated scratch protection coating which makes it less susceptible to damages like CDS or DVDS.
What makes flash media more energy efficient and portable than HD media?
Unlike HD media, Flash media doesn’t contain moving parts
What was magnetic tape initially used for and what is it used for now?
It was initially used for recording sounds but can now record data
define data access speed
how quickly data can be read from or written to media
define bits
a single unit of information which holds two value- 1 or 0.
Arrange all the media we just discussed in a table in terms of data access speed, maximum storage capacity, uses, cost per gb, portability.
Arrange all the media we just discussed in a table in terms of data access speed, maximum storage capacity, uses, cost per gb, portability.
How does each type of media interpret 1s and 0s
Hard disks can change the the magnetic charge of a platter to positive or negative depending on the value being a 1 or 0.
optical media uses tiny bumps on the surface of the disk to represent 1s and 0s.
Magnetic tapes can change the magnetic charge on the tape to positive or negative depending on the value being 1 or 0.
Flash media uses different levels of electric charge held in tiny individual cells to represent 1s and 0s.
Read and write heads
the part of the disk drive that passes across the platters on a very thin layer of gas above the platters
seek time
the time it takes to locate the area on the disk where the data to be read is stored
capacity
the amount of data that can be stored on data
