Storing and Retrieving Flashcards
What is Storing and Retrieving?
It is the two step process by which data or information can be saved and reloaded
What is the role of Storing and Retrieving?
Allow other processes to take place
Allow a temporary halt in system
Back up and Recovery
To assist the transfer of data/information
What is virtual RAM?
Once primary storage is full, data that has processed is saved to the secondary storage. This secondary storage acts as an extension of the RAM and is known as virtual RAM.
Although this is much slower than normal RAM
What are types of commonly used backups?
Full back ups and partial backups
Difference between Random and sequential access in Hardware?
Random access is the ability to go access any item from any location, whereas sequential access is where a file must be accessed through linear sequence and sort through all prior files
Is any storage device completely permanent?
No, there are only degrees of permanence, when comparing things like a hard disk to a CD ROM.
What is RAID?
Redundant Array of Independent disks is a data virtualisation technology meaning it stores data in two or more disks operating in parallel to increase performance and/or reliability
What is Raid 0?
Uses the process of striping to split data into chunks and store equally across a minimum of two drivers.
Provides greater performance but little redundancy as if one drive fails all data is lost
Useful for non-critical data
How have the optical disks changed over the first 3 generations ?
The first generation was mainly just used for storing music and computer software, read with infrared lasers (CDs).
The second generation was used to store greater amounts of data, mainly DVDs and was read with a visible normally red laser which had a smaller beam.
The third Generation was designed for high deffiniton, mainly BluRay, and was uses blue lasers which can focus the beam width more.
The smaller the beam width the more data could be stored and accessed .
What is Flash Memory ?
A non-volatile, electronically erasable and reprogrammable, so it is non-volatile. Similar to RAM and ROM.
Recently beginning to replace hard disks
How is information stored and retrieved from hard disks?
The hard disk consist of several platters stacked on top of each other which spin. The information is stored on the surface of the platters in sectors and tracks, which are read and written to by the head which floats above the surface of platter and uses magnetisation to access data.
What are magnetic tapes used for and why?
They are often used fro backups, as they do not have to be accessed regularly, and it is cheaper and provides lots of space
What software is used for Storing and Retrieving ?
Hardware to software interface File management software DBMS File formats for different data types Internet Browser Encryption/password protection Security of stored data
How do users interact with the process of storing information.
Interacts with application to initiate save, which then continues on through the software to the device drivers and then across to the buffer and firmware, which will save data.
What are the two types of locking when multiple users are accessing databases and how do they function?
Pessimistic locking - the first user to start editing locks the record, and no one else can edit it until the record is saved.
Optimistic locking - assumes conflict rarely occurs, and anyone can make changes to record. But if two users are working off same original data and one saves theirs first, the other must decide whether to keep the changed records and discard their own, or replace the other users with theirs.
How does two key encryption work?
There is a public key which can be given to anyone to encrypt data, there is also a private key which is known only to certain people and allows the data to be decrypted.
Social and Ethical Issues of Storing and Retrieving?
Security of stored data
Unauthorised retrieval of data
Advances in technology
Non computer tools?
Paper based storage systems
Microfiche
Libraries
