Topic 6: The Need For Regular And Systematic Backup Flashcards
What are viruses
Places where you are likely to get viruses
A virus is a program that copies itself automatically and usually carries with it some payload which causes damage
- banners/adverts
- downloads from sites
- e-mail e.g external email or internal email
- optical/magnetic media
Trojans
Worms
- A program that performs a legitimate task but also carries with it undesirable function u may install this as a download file from the Internet as a useful file
- a worm is a program that keeps replicating itself automatically and taking up more and more disk space the purpose of this is to slow down the system
How to prevent viruses
- install virus checking software
- don’t open emails/file attachments from unknown sources
- have a clear acceptable use policy for all staff
- do not allow programs e.g games, video or movies TV downloaded onto the organisations system
- if possible on voice users from being able to use their own removable media
Backup procedures
Where to keep backup copies
- Those actions a person or organisation can take to ensure that regular backup copies are taken
- keep backup copies offsite but ca be inconvenient
- make one person responsible for takin of backups
- backup copies in a fireproof safe>protect them from theft &the damage caused by a small fire (only fireproof for a limited of time)
Methods of keeping backup copies of site
-use removable storage media e.g. Removable magnetic hard drives, pen/flash drives, Zip drives and memory cards
On-line backup services
Advantages
Good because he paid for the service according to the amount of data stored using this
A:-back up data is stored on server of the provider so back up is not kept on the site with original data
-to prevent security problems all data is encrypted before being sent over Internet&only person who owns data can access it
D:-you need to trust organisation with data
Two ways of scheduling back up
- can be taken automatically by scheduling a time for the backup start when being taken they slow down the computer so it’s better to be taken when computers are switched off
- backups can be taken manually
Three different types of backup:
- Full backup: involves making a copy of all the files on the system
- incremental backup:backs up the files which have changed since the last full backup but only back up the data which has changed since the latest backup (much smaller and faster back up)
- differential backup: backs up all the changes made since the last full backup
The strategy used for the backup and recovery of data depends on
- what: what needs to be backed up
- when: (how often backups are taken)
- how: depends amount of storage capacity needed
- storage
Choice of backup device/media depends on
- storage capacity
- portability of device(weight and size)
- access time(time it takes for device to access a specific piece of data)
- transfer rate(how long it takes for data to be written to or read from)
Name of backups, cost, storage capacity, speed
- floppy disk:cheap,1.44mb,slow,not all com have drive to read them -flash/pen drive
- CD-RW: free as comes with ,upto 700mb, moderat
- DVD-RW: free as usually built in, upto 4.7GB, m
- hard drive(fixed): free as built in, storage capacity=160- 250gb &increasing all the time, fast
- hard drive(external or remove able): moderate, up to 500GB and growing, fast
- magnetic tape drive: expensive, up to 8tb,fast
- Internet backup: cheap, unlimited storage, slow
Examples of optical media
Problems
- CD-R
- CD-RW
- DVD-RW
- transfer rate is low which means bCkups take longer
What viruses can do
- display annoying messages on the screen
- delete programs or data
- use up resources, making your computer run more slowly
