1. Utility Software
compression; defragmentation; backing up; encryption Revision YouTube clip:

2. Starter - Guess the catchphrase
Defragment
Format
Backup
Data compression

3. Lesson Objectives To understand the need for Utility Software
To be able to describe the purpose of
Encryption Software
Defragmentation
Data Compression
To understand the role and methods of backup
Full
Incremental

4. What is Utility Software?
Modern operating systems include a range of programs that perform a collection of useful functions:
Keep your system secure
Keep your secondary storage drives organised
Maintain the system
These programs are called utilities.
We will now take a look at some of these.

5. Encryption Software
Encryption utilities use algorithms to scramble data to change it from plain text to cipher text.
Cipher text can only be read if it is decrypted using a private key.
You can encrypt your entire hard disk, or particular files or folders.
Question: Why might the school encrypt certain folders stored on its server?

6. Hard Disk Defragmentation (1)
Data is stored on hard disks wherever there is available space, meaning it can become scattered across different sections of the disk.

7. Hard Disk Defragmentation (2)
Defragmentation utilities reorganise files on a hard disk to put fragments of files back together and collect free space.
Over time, these ‘building blocks’ get fragmented over the hard disk. This means that reading a file takes longer as the hard drive needs to be searched in multiple places instead of one area.
Defragmentation therefore reduces the movement of the read/write head of the hard drive on the surface of the disk, speeding up file access.
The result is that it speeds up access to files stored on your hard drive.

8. Popular compression software includes 7zip, WinRar, PeaZip and WinZip
Compression utilities reduce the size of a file so that it takes up less disk space and is quicker to download over the internet.
Compressed files need to be decompressed or extracted before they can be used.
There are two compression methods: lossy and lossless.
Popular compression software includes 7zip, WinRar, PeaZip and WinZip

9. Lossy and Lossless Compression
Compression reduces the size of the file by performing an algorithm on the original data. There are two types of compression:
Lossless - The original file can be re-created as no data is lost
Lossy - Some of the original data is lost and the original file can not be re-created
We will look at compression in more detail next lesson.

10. Backup Utilities
Backup utilities take a copy of your files to protect against data loss.
Reasons:
You may accidently delete files
You may be hacked
Your system may get a virus
There are two types of backup:
Full Backup - Every file is copied and back up
Incremental Backup – only files that have changed since the last backup are copied.

11. Backup Types – Full Backup
A copy of all data and software on the hard disk drive / server is copied to a backup medium (e.g. an external hard disk drive / DVD-R) and the medium is kept at a different location
Take a long time to complete (usually overnight)
Recovery takes a long time as it restores all data and programs

12. Backup Types – Incremental Backup
A full backup is made initially
Each night only the files which have been changed since the last incremental back-up are copied
Much faster to complete that full back-ups
Takes much longer at restoring than a Full Back up as the full back up would need restoring first and then every incremental back-up since the last full back up.
Incremental backup only backs up new files it recognizes since the last backup.