A backup is a copy of your files that will be able to reproduce the original, if it is lost, damaged or stolen.

Transcription

1 Backup Strategy

2 Backup strategy A backup is a copy of your files that will be able to reproduce the original, if it is lost, damaged or stolen. Two or even three backups can be made. Backups should be kept in a different location from the original copy. Operating systems can be used to create backups. Special-purpose backup utilities & software can used to create backups.

3 Selecting backup media What type of media/system should be used to back up files? Off-site data replication systems. An external company is used to backup files. A high speed network is used to transfer the files from the company s servers to the data replication company's servers. Expensive Magnetic Tape cheap & not technically demanding. Slow to retrieve data. Extra Hard disk s E.g. RAID mirror system - Redundant Array of Inexpensive Drives. RAID is an term used for data storage schemes that divide and/or replicate data among multiple hard drives. A mirror system should be an identical copy of the original files.

4 Selecting backup media (cont d) Think about. The amount of data to be backed-up, budget and expertise will determine the type of device/system to be used. Non-mission critical data - does not require to be backed-up e.g. user s MP3 s & applications that can be backed-up from original media (Cd or DVD) How fast does data need to be recovered?

5 Backup media Practical task Search the internet and find graphics of back up media (Hard Disk and Magnetic tape). Label each of the graphics with their name and their capacity e.g. 100GB and their advantages and disadvantages. Search the internet to find a company who offer data replication. Find out what they do and how much it costs.

6 Backup methodology - Frequency Methodology chosen to suite the nature of the organisation & its processing requirements. Full copies all data within the scope of the backup to destination media (e.g. tape or disk) Takes the longest time. Differential copies all files that changed since last full backup. Takes less time than the full backup. Incremental copies all files that changed since last backup of any kind.

7 Media rotation & Version control Backup Rotation (When backup media is used over and over again.) is used to keep down costs. Backup media should be stored in a different location to the original. Should be stored securely off-site & be available for quick retrieval. Re-using media after a predetermined time minimises the number of backups stored off-site. Saves time and money

8 Grandfather-father-son (GFS) Media rotation schedule. Daily backup (Son) Friday becomes Week1 Weekly backup (Father) Week 4 becomes Month 1 Monthly backup (Grandfather)

9 Grandfather-father-son (GFS) The basic method is to define three sets of backups, such as daily, weekly and monthly. The daily or Son backups are rotated on a daily basis with the final one graduating to Father status each week. The weekly or Father backups are rotated on a weekly basis with the final one graduating to Grandfather status each month.

10 Developing a backup strategy System administrator creates & maintains a reliable backup system by determining- 1. What data to backup? 2. How frequent should the backup be made? Every time there is a change Every month End of everyday 3. Which storage media should be used to back up files? Magnetic tape External hard drives Mirror drives Off-site copies 4. What type of version control should be used? GF/F/S This ensures operational continuity in a disaster.

11 Backup Strategy - Scenario Suggest a backup strategy for a small dating agency business. Use the previous slide to help you form your backup strategy. You must mention all 4 points.

12 Describe each of the following common backup methodologies Full Differential Incremental. Grandfather-Father-Son is a common backup media rotation scheme. Describe how it works.