Backups
Backup software will backup files on a network server at regular set intervals. This can be backups to other hard disks (RAIDRedundant array of independent/inexpensive disks. Allows data to be stored in different locations on different disks) or, increasingly, servers on the internet (cloud backup).
RAID (Redundant Array of Inexpensive Disks)
When RAID is employed as a backup strategy, several exact copies of the data transactions (known as mirror images) are created on different disks. All data transactions are recorded on all copies simultaneously.
The mirror images are stored in secure and separate locations. If the system fails, there can be an instant switchover to one of the backup copies.
Grandfather, Father, Son
Data transactions are backed up daily (son), weekly (father) and monthly (grandfather), with the oldest from each set aside.
The daily (or son), backups are saved every night for a week until there are seven 'sons'. At the end of the week, the oldest 'son' will be set aside and known as a 'father'.
Every week a new 'father' is created. At the end of the month when there are four 'fathers', the oldest 'father' is set aside as a 'grandfather' backup.
12 'grandfather' backups will be stored each year.
Further copies should be kept off site, in a secure fireproof location.
Cloud backup
Companies are increasingly using cloud services to backup data. Infrastructure as a Service (IaaS) companies provide online data storage for businesses. IaaS removes the need for organisations to have their own backups 鈥 they can simply download their data when required. Companies generally lease these services from providers of Infrastructure as a Service.
Restoring backups
Backup software also needs to be able to restore the information. When everything on a hard disk is backed up this is known as a full backupAll data is copied regardless of whether it has been changed since the last backup. This takes a long time, so it is possible to back up only data which has changed since the previous backup. This is known as an incremental backupA backup of new files and files that have changed..
After a system failure, data must be restored from a backup, copying it back onto the computer system. Network managers can use auditing software to determine the exact time of the loss and use the backup files to restore the system to that point in time.
If hardware has been destroyed or has stopped working, then data must be restored onto new hardware.
Firewalls
A firewallA type of software or hardware that stops unauthorised access to the network. A firewall is a piece of software usually included as a utility within an operating system. protects a network from intruders by controlling what data can and cannot pass through. A firewall can be hardware or software.
A firewall can use packet inspection to open each network packet and read the data inside. If it finds the signature of a virus inside, then it can remove or prevent the packet entering the network. This is known as packet filtering.
It is possible to filter packets using a particular protocolA set of rules for how messages are turned into data packets and sent across networks. and port, for example the data packetA piece of data sent over a network. Messages have to be broken down into binary data packets before they are transferred. protocol used to transfer web pages works on port 80. Firewalls can be used to block particular portThe end point of communication between networks., in this case to prevent users downloading web pages.