Backup and Recovery Strategies

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BUSINESS SYSTEM MANAGEMENT
TOPIC 11 DISCUSS BACKUP AND RECOVERY STRATEGIES

LESSON CONTENT
Introduction  Why backup  Backup location  What data should be backed up  What should you backup onto  Backup procedures


Introduction


Everyone who uses a computer to save or store files will at some time or another experience that heart stopping moment when they realize their files are lost.

Why Backup?


Every day individuals, businesses, and organizations lose their precious files due to a
◦ drive failure, ◦ inadvertent deletion, or other unwanted action or event.



The result is a great deal of stress, anxiety, and in the case of businesses, lost revenue.

Why Backup?
The computer hard drive that stores all your data has moving parts, and in time your hard drive will wear out and fail.  It's just a matter of when. You need to keep a copy of all your important data somewhere else.


Major causes of system errors:
Human act  Natural act  Technical


Major causes of system errors:


Human act ( error, labor unrest, erasure of an important file)
◦ Information system personnel ◦ Authorized user ◦ Non authorized users



Natural act
◦ ◦ ◦ ◦ ◦ ◦ Wind Fire Earthquake Extreme temperature Floods Hurricane



Technical
◦ Hardware ◦ Application software ◦ Systems software (refers to the files and programs that make up your computer's operating system. installed on your computer when you install your operating system.) ◦ Communication ◦ Electricity

Backup Location
You need to store a copy of all your important files in a different location to where your computer is situated.  It's not a great deal of use having the copy of your files on your external hard drive which is constantly plugged into your computer.  A thief won't leave your additional drive for you to recover your lost files, a fire or flood won't distinguish between your computer and your external drive.  At the very least, keep your copy in a different location in your home. If possible, keep your backup copy in an entirely different building.


Backup Location
Some choose to backup their data onto remote servers via File Transfer Protocol (FTP)  Others use the services of off-site backup over the Internet.


What Data Should Be Backed Up?
pictures, videos, music, Microsoft ® Office documents, spreadsheets, databases,  Internet Explorer Favorites and/or Firefox bookmarks, emails etc,  keep a copy of all the programs you use so that if necessary they may be easily reinstalled at a later date.  It would be advisable therefore to copy any new programs you download and install them from the Internet in a special folder that gets backed up as part of your backup routine.
 

What Data Should Be Backed Up?
One especially important program to backup is the program you use for the backup procedure itself.  You'll also need to save the serial number for this program and others in a secure yet memorable location so you can restore your backup to the original location at a later date should you need to.


What Data Should Be Backed Up?


If you use your computer for business purposes you will also need to backup all the information from your
◦ ◦ ◦ ◦ financial software, inventory control, customer databases, and other specialist business files.

What Should You Backup Onto?


There are many different types of media that you may choose to backup onto, and each has their own advantages and disadvantages. The first thing you'll have to work out is what suits your particular circumstance

What Should You Backup Onto?


It's generally a good idea to choose media that allows you to backup all the data you wish to without having to 'span' the backup.
◦ For example, you may need many CDRs to backup all your information. ◦ The problem with this kind of backup is that it requires your intervention to replace the new media as each disk is required

What Should You Backup Onto?


A backup that can automatically run without your intervention will save you a great deal of time over the long run.
◦ An external USB hard drive for example can plug straight into a computer and provide an instant large capacity space for your backups.

Backup procedure


Business and homes users can perform four types of backup.
◦ ◦ ◦ ◦ Full Differential Incremental Selective



Continuous data protection CDP (typically is used only by large enterprise)

Full backup
Sometimes called an archival back up  Copies all of the files in the computers  Provides the best protection against data loss because it copies all program and data files.  Performing a full back up can be time consuming


Differential backup
Copies only the files that have changed since the last full backup  Then creates copies of all the files that are different from the ones in the full backup.


Example:
Let us take for example that you are taking a full backup of a folder 'Test Folder'  containing Four files


◦ File A, File B, File C and File D on day 1 and have scheduled to take differential backups of the folder on a daily basis. ◦ The following table explains what would be the contents of successive differential backups, if you modify the files as given in column two.

Day

Files Edited

Type of Backup taken

Files contained in the full backup (Test Folder_full_files.cb u) File A, File B, File C and File D

Files contained in the differential backup (Test Folder_dif_files.cbu)

Day 1

Full

Day 2

File A

Differential

File A, File B, File C File A (modified version) and File D (original versions) File A, File B, File C File A (version modified on and File D (original Day 2) and File B (version versions) modified on Day 3) File A, File B, File C File A (version modified on and File D (original Day 2), File B (version versions) modified on Day 4) and File C (version modified on Day 4)

Day 3

File B

Differential

Day 4

File B Differential and File C

Incremental backup
Copies only the files that have been changed since the last or last incremental backup.  With incremental backup, you have the full backup and one or more incremental backups.  The first incremental backup contains changes since the last full backup.  Each subsequent incremental backup contains changes only since the previous incremental backup


Example:
Let us take for example that you are taking a full backup of a folder 'Test Folder'  containing Four files


◦ File A, File B, File C and File D on day 1 and have scheduled to take incremental backups of the folder on a daily basis. ◦ The following table explains what would be the contents of successive incremental backups, if you modify the files as given in column two.

Day

Files Edited

Type of Backup taken

Files contained in the full backup (Test Folder_full_files.cbu)

Files contained in the incremental backup (Test Folder_inc_files.cb u)

Day 1

Full

File A, File B, File C and File D

Day 2

File A

Incremental

File A, File B, File C and File D File A (original versions) version) File A, File B, File C and File D File B (original versions) version)

(modified

Day 3

File B

Incremental

(modified

Day 4

File B Incremental and File C

File A, File B, File C and File D File B (version (original versions) modified on Day 4) and File C (version modified on Day 4)

Selective backup
Sometimes called partial backup  Allows the user to choose specific files to back up, regardless of whether or not the files have changed since the last incremental backup.


Continuous data protection (CDP)
  





Sometimes called Continuous backup Backup plan in which all data is backed up whenever a change is made Because CDP is costly, few organisation have implemented CDP, its popularity is growing quickly as the cost for this technology is falls. CDP require little or no maintenance where compared to other backup method. Many experts believes that CDP will replace all other types of backup in the future

Backup Procedures


Continuous data protection provides automatic data backup whenever data is changed in an enterprise

Backup procedures
Specify a regular plan of copying and storing important data and program files.  Generally, users should perform full backup at regular intervals, such as


◦ at the end of the week and ◦ at the end of the month


Between full backup, you can perform differential and incremental backup.

Backup procedures


Whatever backup procedures a company adopts, they should be:
◦ Stated clearly ◦ Documented in writing ◦ Followed consistently

Disaster recovery plan
A disaster recovery plan is a written plan describing the steps a company would take to restore computer operations in the event of a disaster  Contains four major components


Emergency plan

Backup plan

Recovery plan

Test plan

The emergency plan
Specifies the steps to be taken immediately after a disaster strikes  The emergency plan usually is organized by type of disaster, such as fire, flood, earthquake.  Depending on the nature and extent of the disaster, the procedures that are followed in emergency will differ.


The emergency plan


All emergency plans should contain the following information:
◦ Names and telephone numbers of people and organisation to notify ( eg. Management, fire department, police department) ◦ Procedure to follow with the computer equipment (e.g. equipment shutdown, power shutoff, file removal) ◦ Employee evacuation procedures ◦ Return procedure that is who can reenter the facility and what action they are to perform.

The backup plan






Once the procedures in the emergency plan have been executed, the next step is to follow the back plan. The backup plan specifies how an organisation uses backup files and equipment to resume information processing. The backup plan should specify the location of an alternate computer facility in the event the organization’s normal location is destroyed or unusable.

The backup plan




When operations are so important that the organisation cannot afford to lose the operation to a disaster, the organisation often maintain a HOT SITE, which is a separate facility that mirrors the systems and operations of the critical site The hot site always operate concurrently (Operating or acting in conjunction with another.) with the main site, so that if either site become unavailable, the other site continues to meet the organisation’s needs

The backup plan
The process of one system automatically taking the place of a failed system is called FAILOVER.  COLD SITE is a site that mirrors the critical site, but does not become operational until the critical site becomes unavailable.  When using a COLD SITE, some time elapses between the disaster and when the cold site become functional.


The backup plan


The backup plan identifies these items:
◦ The location of backup data, supplies and equipment ◦ The personnel responsible for gathering backup resources and transporting them to the alternate computer facility ◦ A schedule indicating the order in which, and approximate time by which each application should be up and running

The backup plan
For a backup plan to be successful, the organisation must backup all critical resources  Also, additional people, including possible nonemployees, must be trained in the backup and recovery procedures because personnel could be injured in a disaster.


The backup plan
The location of the alternate computer facility is important.  It should be close enough to be convenient, yet not so close that a single disaster, such as earthquake could destroy both the main and alternate computer facilities


The backup plan
Some organisation preinstall all the necessary hardware, software and communication devices at the alternate computer facility.  These facilities immediately are ready in event of a disaster.  In other cases, the alternate computer facility is simply an empty facility that can accommodate the necessary computer resources if needed.


The backup plan


One more alternate computer is to enter into a RECIPROCAL BACKUP RELATIONSHIP with another firm, where one firm provides space and sometimes equipment to the other in case of disaster.

Recovery plan
Specifies the actions to be taken to restore full information processing operations.  As with emergency plan, the recovery plan differ for each type of disaster.  To prepare for disaster recovery, an organisation should establish PLANNING COMMITTEES, with each one responsible for different forms of recovery.


Recovery plan


For example, one committee is in charge of hardware replacement, another is responsible for software replacement.

The Test Plan
Provide assurance that the disaster plan is complete, it should be tested  Disaster recovery test plan contains information for simulating various level of disasters and recording an organisation’s ability to recover.


The Test Plan
In a simulation, all personnel follow the steps in the disaster recovery plan.  Any needed recovery action that are not specified in the plan should be added.  Although simulation can be scheduled, the best test of the plan is to stimulate a disaster without advance notice.


In summary
Why is computer backup is important, and how is it accomplished?  What are the steps in a disaster recovery plan?


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