Computer systems- module 23) Flashcards
What is meant by ‘non-volatile’?
Data remains after power switched off.
What is ‘Cloud computing’?
Term for processing data on computer systems belonging to someone else, + accessing them through Internet.
What do storage companies use?
Ranks of data servers in stacks either large traditional magnetic hard drives or increasingly as capacity expands solid state drives.
What are the advantages of cloud storage?
Access any with internet connection.
For businesses offices across world can access same files.
Disaster recovery easier- assuming storage provider not affected by whatever hit system.
Costs generally lower per mB + storage capacity more flexible than local storage.
What are the disadvantages of cloud storage?
Need reliable internet connection- especially if handling large files.
Relying on someone else to keep files safe.
Moving from 1 provider to another can be difficult.
Can be data ownership issues if provider sold to another company.
What is an example of data ownership issues if provider is sold to another company?
When Facebook bought Instagram, all Instagram content transferred ‘license to use’ content to Facebook- without users’ express content.
What are the advantages of local storage?
Have control over your data.
No internet connection required- have direct access.
Saving data faster than cloud storage.
External drives cheap + have considerable capacity for non-specialist to use to extend data storage.
What are the disadvantages of local storage?
Capacity limited by drive space + budget.
Not always convenient to access.
Possibility of theft.
Data recovery in event of disaster down to user.
What is an embedded system?
1 in which computer system plays part in much bigger device. Computer element nearly invisible but essential. Unlike non-embedded systems, embedded systems generally designed to perform single task rather than be general purpose computers.
What is the operation of solid state drives?
SSDs use grid of electrical cells to quickly send + receive data. These grids are separated into sections called ‘pages’ + these pages are where data stored. Pages are clumped together to form blocks.
SSDs can only write to blank pages when isn’t enough space left to store data required. As result SSDs perform less and less well over time.
What are the advantages of SSD’s?
Only drives available that are faster than hard drives are magnetic.
Start up faster since no moving parts.
Some are waterproof.
Ideal for portable USB devices.
What are the disadvantages of SSDs?
Very expensive compared to other forms of storage.
Limited write cycles- wear out much faster than anything else.
Write speeds can be slow.
What is the operation of Optical (CD/DVD)?
Single track of data spiralling from centre to edge of disk. Made up of bumps on 1 side which show up as microscopic pits on the other. Drive motor moves laser + lens system to exactly focus on area to be read/written. Bumps (or pits) reflect laser differently from flat ‘lands’ in between, + electronics in drive interpret this to read the data.
What are the advantages of Optical?
Portable.
On some formats data can be archived as cannot be overwritten (DVD-R/CD-R).
Inexpensive.
What are the disadvantages of Optical?
Require special drives to write to them.
Relatively small capacity.
Easily damaged.
Some compatibility issues across drives.
