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 1. Overview  
 What is preventative maintenance? 
 Why use preventative maintenance? 
 Who uses preventative maintenance? 
 How does preventative maintenance work? 
 What does preventative maintenance cost? 
 2. Preventative maintenance implementation guide 
 What needs to be done? 
 Who does it? 
 Prepare to implement  
 Implementing Preventative maintenance  
 Reviewing the implementation 
 Resources 
 3. Preventative maintenance operations guide  
 What needs to be done?  
 When does it need to be done? 
 Who does it? 
 How is it measured? 
  Resources 
 4. Toolkit  
 Installing a firewall 
 Installing antivirus software 
 Developing fail safes 
 Implementing a backup and restore process 
 Maintaining computers (Apple) 
 Maintaining servers 
 Maintaining switches, hubs and routers 
 Setting up a maintenance schedule 
 Setting up RAID 
 5. Review of Preventative Maintenance 
 Recap of Preventative Maintenance 
 Checklist 
Implementing a backup and restore process
What is a backup and restore process? Why backup? Choosing an appropriate backup system for your school Using the back up system Testing the backup system

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What is a backup and restore process?
Most people understand the importance of backing up critical data. But most of the time back- ups, if done at all, happen in a haphazard way - usually after losing some data.

Particularly where data is stored on the server you need to implement a formal and routine back-up process. Of course, data back-up is of no use unless there is a corresponding process for recovering and restoring the data.

This guide will show you how to implement a data backup-and-restore process that should ensure that you never lose critical data again.
Why backup?
Computers can and do fail and they sometimes fail in ways that render the data stored on them unrecoverable. In addition, there are disasters to consider. If your server room were to be destroyed by fire or flood, you could rebuild the servers - but could you restore the data? Sometimes data simply needs to be restored because a user has accidentally deleted a vital file. How can you be sure the data is available when required?

A system that ensures a minute-by-minute back-up of all data on your network may be prohibitively expensive for your school. On the other hand, backing up data on floppy disks once a year will probably not give you the level of protection you need. The following section will help you choose the right system for your school.
Choosing an appropriate backup system for your school
When choosing a back-up system, consider the following factors first .
  • How dynamic is the data stored on the server? How often does it change and in what ways does it change?
  • How much data needs to be backed up, and at what rate is the amount of data growing?
  • How much time is available to make the back up?
  • If a partial or complete restore of data is required, how quickly must it take place?  As a rule of thumb, restoring data takes twice as long as the original back-up.
  • Do you need to be able to restore all the data in one go or can you do it by individual files?
  • How often does data need to be backed up? Will nightly back- ups suffice or does some critical administration data need more frequent back-up?
  • How many copies of data back-up are required? Multiple copies may require additional back-up systems or may use the same back-up systems more than once – thereby requiring extra back- up time.

Once you have an idea of your backup-and-restore needs, you can proceed to acquire the necessary hardware and software to create and manage your back-ups.
When choosing a back-up technology, consider the following factors:
  • reliability of the hardware and the media
  • cost
  • storage capacity
  • likely frequency of restorations
  • the importance of fitting the entire back-up onto a single piece of media. This last may determine whether the back-ups can be unattended (in the early hours of the morning, for example) or whether staff need to change media during the back-up process.
Using the back up system
Most network operating systems maintain special information for each file on the system. One of these is called the archive bit, which indicates the back-up status of the file. When a user modifies a file, its archive bit is set to ‘on’, indicating that the file should be backed up. When the back-up is accomplished, the archive bit is cleared. Using this archive bit and your back-up software, you can make different types of back-ups: full, incremental and differential.
  • Full back-up
    All selected directories and files are backed up, regardless of their archive bit state. Full back-ups clear the archive bit on all the backed-up files when they are finished.
  • Incremental back-up
    Only the files with their archive bit set are backed up. This backs up all files changed since the last full or incremental back-up. Incremental back-ups clear the archive bit of the files that are backed up.
  • Differential back-up
    This is similar to the incremental back-up in that it backs up only files with their archive bits set. The difference is that differential back-ups leave the archive bit set. Subsequent differential back- ups will back up those files again, plus any new ones that have been modified.

Why are there different types of back-up?
To do a full back-up of your data every night may not be feasible for the following reasons,
  • A full back-up may take too much time.
  • A full back-up may require that staff be present to swap media (when one disk or tape is full and a new blank needs to be inserted in the drive).
  • A full back- up may reduce the lifespan of your back-up media and drives by giving them extra work to do.

On the other hand, doing only incremental back-ups may increase the risk of data loss. So it is best to combine the back-up approaches by using a combination of back-up types. One common way to mix these types is to perform a full back-up of the system once a week and perform only incremental or differential back-ups each day.

You now need to plan a back-up rotation strategy that addresses how back-up media is rotated. Back-up rotations are designed to accomplish the following goals:
  • rebuild the system with the most recent possible data in case of a catastrophic failure
  • restore files from older media that may have been accidentally erased or damaged without anyone noticing the potential loss of data at the time
  • protect against back-up media failure
  • protect the data from an environmental failure, such as a fire, that might destroy the original system and data.

The most common rotation system is called the ‘grandfather-father- son (GFS) system. Usually this uses eight tapes. The system works as follows:
  • Label four of the tapes as ‘Monday’ to ‘Thursday’ and four others as ‘Friday1’ to ‘Friday4’.
  • Every Monday to Thursday, make an incremental or differential backup using one of the labelled tapes and replacing the data stored on the previous week.
  • Each Friday make a full back-up using the tape for whichever Friday in the month you are on (1-4).
  • In addition, on the last day of each month make a month-end tape which you store off site and never reuse. This is your fail- safe in case of environmental failure at the school.
Testing the backup system
No matter how sophisticated or comprehensive your back-up system is, you will never know if it works unless you actually test it. Without testing, you can have no confidence in the backups as errors may creep into the back-up system. Examples of such errors include:
  • failed backup software. - the backup software simply fails and when you restore the data from the backup media, many files are missing or corrupted
  • incomplete data - the backup may be configured to back-up only part of the data
  • magnetic interference - tapes are susceptible to damage if stored near a magnetic field such as a loudspeaker
  • encryption - when the back-up software was installed and configured, someone set it up to write encrypted backup tapes and now nobody knows what the password is
  • old version - an old back-up tape cannot be restored because it can only be read by an earlier version of the back-up software
  • poor quality media - cheaper media may degrade and be unreadable when needed
  • tape breakage - a back-up tape breaks during the back-up and is sent off site without anyone noticing.
  • Back-up crash - if the server crashes during an unattended backup, it is not always obvious that the back-up has not completed.
These are just some of the things that can go wrong. The important thing is to realise that there is a number of things that can go wrong with a back-up operation. Some of those things will be intermittent. Others may affect all back-ups, meaning that all your back-ups will be useless.
The only way to tell if your backups are working is to actually load a back-up tape and see if the data is correctly restored. This may be difficult or impossible if you have filled the hard disk to capacity. However, testing your back-ups is such an important activity that it really is worth either reducing your disk usage to less than half of your hard disk, or finding another hard disk so that you can perform a test restore.
When testing back-ups always ask yourself if you would feel comfortable erasing your hard disk right now, and restoring it from your backups.
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