3.7 Utilities

Compression is also discussed on the networks page.

Popular packages, such as WinZip , can be used to compress data; BUT in an examination do NOT assume the examiner knows what WinZip is - explain what it does.

This definition does not take into account subtleties like "trojan horses" but it will do for your exam. Find more info at Symantec's AV Center.

On this page [ system utilities | defragmentation | data compression | virus checkers ]

System utilities include those which do basic file maintenance operations:

• copy
• delete
• rename
• create folders (directories)

 and some which are typically provided as part of the system software: 

•  system back-ups
•  media formatting
•  disc maintainance (eg defrag)
•  archiving
•  disk compression
•  defragmentation
•  virus checkers

Some of these will be considered briefly here and some are considered on other pages.

System Backups
This topic is discussed in the section on errors.  Backing up data will be a routinely scheduled operation in every business whose activities depend upon data held in their computer systems.  For many organizations their data is everything; banks, for example, deal as much or even more with data as they do with money.    

Media Formatting
You can refer to the the memories page for details of how discs are structured using sectors and tracks. Formatting a disc involves marking the surface so that these can be detected by the operating system. All types of media need to be prepared in some way for use on a computer system and each operating system will typically use a different media format.

Archiving
In organisations with very large amounts of data which is rarely accessed but still needs to be kept (legal firms keeping details of past cases, insurance companies keeping old contracts, oil companies keeping exploration data on different countries) the data will be archived.  The weather case study of 2001 is a case in point.  Vast quantities of data are gathered and stored for use with medium and long-range forecasting models.  Often such data is stored in an automated retrieval system.  For example, cassette tapes can be used with programmable machines used to fetch data for a particular week.

Defragmentation
When files are first stored on a newly formatted disc, they are stored in continuous blocks (a block is a given sector in a given track on a given surface).

If the green file is removed and another file added which, say occupies 3 blocks; the operating system uses the first two available block previously occupied by the green file (blocks 3 and 4) and then links to the rest of the file in the block 7.

The red file is now fragmented .  If this process continues with the addition and deletion of many files then a single large file can be split up over different parts (even different surfaces) of a disk.  This increases the time taken to access and load the file into memory.

• save space on backing store
• save time when transmitting data (eg over the internet)

Compression is also used with media files such as graphics, music and video files.  In this case, unlike with text, some quality is sacrificed in the compression process.  Again, in the exam, talk about compressing music files rather than assume everyone already knows what an mp3 is.  This is not because the examiner doesn't know but because you have not demonstrated that YOU know!

• a computer program which
• has the ability to replicate itself and
• has a "payload" - ie does something on the target system

This topic completes the common core.

Back to top

related: [ Core home | previous: errors ]

Questions or problems related to this web site should be addressed to Richard Jones who asserts his right to be identified as the author and owner of these materials - unless otherwise indicated. Please feel free to use the material presented here and to create links to it for non-commercial purposes; an acknowledgement of the source is required by the Creative Commons licence. Use of materials from this site is conditional upon your having read the additional terms of use on the about page and the Creative Commons Licence. View privacy policy.