Networking Objectives Understand what the following policies will contain – Disaster recovery – Backup – Archiving – Acceptable use – failover

Networking Networking policies A companies (and schools) network can effect many people. That means it is important to have written policies in order to ensure that everything can be kept up and running for as long as possible. A policy is simply a document outlining rules and procedures which must be followed. There are a number of key policy documents which will be looked at in this PowerPoint.

Networking Disaster recovery Or the “Oh my god it is all gone!” policy... A disaster for a network would be if a main server fails and all the data corrupted. This could be caused by a fire or an act of god. It could also be caused by many other factors. Regardless of how the disaster happened it is important that we can recover from the critical failure. A network would suffer a disaster if the whole network went down and critical resources were lost. The key is that resources are lost.

Networking Disaster recovery Disaster recovery policy should say how we can get the data back! This could involve – Accessing backed up data and importantly where that data is stored. Building in redundancy. This means having a second server which can start running when the first one fails. Which services should be restored before others. For example access to files before . This is very dependant on the company in question.

Networking Activity The key network resources in school are – Storing student files VLE Student database Access to files outside of school (staff only) Taking registers on the computer Shared files (common drive) Decide on which order you would restore these in a disaster recovery.

Networking Backup Backup is the process of copying files from the main area which it is used to a separate area. That way if a file is deleted the backup can be accessed in order to retrieve the lost file. Every network has a backup policy as it is very common for files to get deleted or lost. When creating a backup policy you need to decide on – Where will the backup be stored? What will it be stored on? How often will the backup be taken? How long will a backup be kept?

Networking Backup hardware When we backup our files at home we may use a memory stick or external hard drive. We may even use a CD or DVD to backup our files. A network will tend to use magnetic tapes or hard drives. The amount of data which needs to be backed up could range in the tera bytes (1000 GB) which means that no DVD or external hard drive could fit it all on. It certainly could not fit more than one version of the backup. It is common to have a server which is completely dedicated to backing up files!

Networking How often? A backup will take a long time! It can take many hours to back up all of the files on the network and it could tie up the network for a long time. This means that the backup will occur at night when everyone has gone home. The more often we run the backup the better. Unfortunately this means we need to have bigger and bigger capacity in order to do this. There is a trade off between how often we do a backup and how long we can keep the backup. Eventually we will need to delete old backups to make way for the new ones. The backup policy needs to make that decision.

Networking Where it will be stored? Where the backup is stored depends on how important the data is! It is common to have backups on the opposite side of the building in a fire proof box. This limits the chance of both the backup and the main server being destroyed by a fire. However to keep it really safe it should be stored off site. The biggest issue with this is the additional cost as well as the extra time it would take to make a full backup.

Networking Clever backups In order to keep the size of a backup small only the files which have changed are backed up. The first backup will copy all files. After that each subsequent backup will only copy over the files which have changed. This dramatically reduces the overhead of a backup and means that it can be done more often. At school we backup every day and hold backups for about one month.

Networking Activity Mr Johnson owns a small shop which sells tropical fish. He stores all of his files on a server in his shop. Suggest a backup policy for him. When creating a backup policy you need to decide on – Where will the backup be stored? What will it be stored on? How often will the backup be taken? How long will a backup be kept?

Networking Archiving Some files are really important and must never be deleted. However, over time, these files build up and take up space. The more space used up the slower the system becomes overall. Some of these files will not be common use. As such they will could be archived. Archive is the process of moving a file from the main system to a special archived system. That way if it is needed again we can still access it. Archiving old files will speed up the overall running of the main file server.

Networking Archiving Main server Archive server Old files are moved from the main server to the archive Old file

Networking Archiving Main server Archive server This speeds up the main server!! Old file 3050

Networking Archiving Main server Archive server If the file is requested it must be copied from the archive back to the main server. A copy is then sent to the user Old file Request packet Old file

Networking Archiving The main decisions to make for a archive are – How old must a file be to be archived? How long will the archive be held for? Where will the archive be based? NOTE – We measure the age of a file from the time it was last accessed not when it was created. This measure is unique to archiving.

Networking Activity What information or files do you think the school archives? When do we delete your user areas once you leave? What would you do? Create a short policy for archiving student user accounts.

Networking Acceptable use The first time you log onto a computer network you are accepting their terms of use. This is detailed in a policy called acceptable use policy. It details what you are allowed to do and what you may not do. This covers What internet sites you are allowed on How you may use What files you can copy on the network Where you can store your files Breaking the acceptable use policy could lead to disciplinary action such as loss of access or being fired.

Networking Activity Excitement time! Read the schools acceptable use policyschools acceptable use policy Is there anything in there that surprises you? Did you know you have to comply with it!

Networking Acceptable use Every school and company must have this policy. It is designed to protect them against malicious software and lost productivity. The school policy is fairly tame compared to some companies. Did you know that some companies reserve the right to log every keystroke you make! Some companies would fire you if you tried to use websites such as facebook or play a game during the day. How many of you would of been excluded if we did that in school?!?!

Networking Failover Failover is a computing term which is very closely linked to disaster recovery. When the main server goes down the loss of resources will occur. However failover allows you to automatically switch to a backup server the second the server failed. This automatically switching is known as failover.

Networking Failover Router with failover Main server Backup server Packet The router will send packets to the main server under normal conditions

Networking Failover Router with failover Main server Backup server Packet If the server fails the packet will be lost.

Networking Failover Router with failover Main server Backup server Packet In failover the packet is sent to the backup instead. That way the user has no idea that the server has failed!

Networking Failover Failover is expensive as you have to have 2 (or more) of everything! At school we use failover for our file server. We have two file servers each with four hard drives. If one fails the other one takes over. It is common to use a less powerful “backup” server as it will only be operation while the main server is repaired. This could only be a few days. This helps keep costs down.

Networking Activity Make notes on the different policies. If your work in this PowerPoint is good you may wish to include it in your notes.