Backup and Recovery
Topic Six
How many of you have ever lost work on a computer?
How often do you back up your work or PC or laptop?
Threats to ICT Systems• Computer/hardware failure• Deliberate damage• Accidental damage• Theft• Hacking• Fire• Terrorist attack• Natural disasters• Viruses• Software bugs• Power cuts
Malpractice and Crime
•Malpractice – improper, careless or unprofessional conduct
•Crime – illegal act, punishable by law, contravention of a law
Viruses
• Main threat from malicious damage• Program that replicates itself and
infects computers.• Usually carries with it a payload that
causes damage– Annoying messages– Delete programs or data– Use up resources and slow down
running
Viruses• On the internet find out the names
and ‘modus operandi’ of three different types of virus.
• Viruses take time and resources to get rid of.
• Trojans – performs a legitimate task but also has an undesirable function
• Worm – keeps replicating itself using more resources up
Viruses
• Spread by– Email (commonly attachments)– Intranet– Shared disks– Banner adverts– Downloads
Preventing Viruses• Install virus checking software• Do not open emails from unknown sources• Do not open file attachments unless from
a known source• Keep software up to date• Have an AUP• Train staff to be aware of problems• Do not allow programs such as games etc• Prevent use of user removable media if
possible
The Importance of Backup• Backup procedures• Copies taken regularly on a routine
basis• Copies kept away from the computer
system• Copies could be kept in a fireproof
safe• Copies preferably kept off site
Online Backup Services
• Advantage is the procedure can be automated
• Backup is off site on a separate server• Data is encrypted before sending to
prevent security problems• Disadvantage is trust and cost• www.datadepositbox.com/democitytv.
asp
Backup Procedures
• Use a different tape/disk each day and rotate them
• Make one person responsible• Keep backups safe• Rehearse recovery procedure
Scheduling Backups
• Backing up uses system resources so system will slow down
• Backups can be manual or automatically scheduled
• Use of ancestral file system (3 generations)
• Full backup and partial (transaction) backup
The Needs of Individuals
• Backup strategy– What– When– How– Storage
What
• Types of backup– Full backup– Incremental backup– Differential backup (cumulative)– Continual backup (mirrored disks)
When
• Dependant upon how much data changes and how often it changes
• Individuals• Organisations
– Systematic– Often in the evening
How
• Wide variety of storage media• Depends upon
– Storage capacity– Portability– Speed of data transfer– Speed of access– Requirement to be connected to
different devices
Backup Media
• Magnetic tape (cheap and removable)
• Magnetic disk (simple)• Optical media (slow transfer
rate)• Pen/flash drives (small storage)• Floppy disks – no more!
Responsibility for Backups
• Why is this needed?• Recovery procedures
– Alternative accommodation– Availability of staff at short notice to
recover backups– Availability of hardware to run backups– Training for staff on recovery procedures– Alternative communication lines
Continuity of Service
• Dual processing• RAID systems• Clustering• Examples of organisations
needing continuity of service?
Homework
• Case Study 1 on page 215 of your text book.
• Please have ready to hand in first lesson after the half term.