backup and recovery strategies
TRANSCRIPT
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BUSINESS SYSTEM
MANAGEMENTTOPIC 11
DISCUSS BACKUP AND RECOVERY
STRATEGIES
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LESSON CONTENT
Introduction
Why backup
Backup location
What data should be backed up
What should you backup onto
Backup procedures
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Introduction
Everyone who uses a computer tosave or store files will at some time or
another experience that heart stopping
moment when they realize their filesare lost.
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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.
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Why Backup?
The computer hard drive that stores allyour 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.
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Major causes of system
errors: Human act
Natural act
Technical
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Major causes of system
errors: Human act ( error, labor unrest,
erasure of an important file)
Information system personnel
Authorized user Non authorized users
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Natural act
Wind
Fire
Earthquake
Extreme temperature
Floods
Hurricane
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Technical
Hardware
Application software
Systems software (refers to the files andprograms that make up your
computer's operating system. installed on
your computer when you install your
operating system.)
Communication
Electricity
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Backup Location
You need to store a copy of all your importantfiles in a different location to where yourcomputer is situated.
It's not a great deal of use having the copy ofyour files on your external hard drive which isconstantly plugged into your computer.
A thief won't leave your additional drive foryou to recover your lost files, a fire or floodwon'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 yourbackup copy in an entirely different building.
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Backup Location
Some choose to
backup their data
onto remote
servers via FileTransfer Protocol
(FTP)
Others use the
services of off-sitebackup over the
Internet.
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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 easilyreinstalled at a later date.
It would be advisable therefore to copy anynew programs you download and install themfrom the Internet in a special folder that getsbacked up as part of your backup routine.
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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 serialnumber for this program and others in
a secure yet memorable location so
you can restore your backup to theoriginal location at a later date should
you need to.
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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.
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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. Thefirst thing you'll have to work out is
what suits your particular
circumstance
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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 isthat it requires your intervention to replace
the new media as each disk is required
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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 examplecan plug straight into a computer and
provide an instant large capacity space for
your backups.
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Backup procedure
Business and homes users canperform four types of backup.
Full
Differential Incremental
Selective
Continuous data protection CDP(typically is used only by large
enterprise)
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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 allprogram and data files.
Performing a full back up can be time
consuming
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Differential backup
Copies only the files that havechanged since the last full backup
Then creates copies of all the files that
are different from the ones in the fullbackup.
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Example:
Let us take for example that you aretaking a full backup of a folder 'TestFolder'
containing Four files File A, File B, File C and File D on day 1
and have scheduled to take differentialbackups of the folder on a daily basis.
The following table explains what wouldbe the contents of successive differentialbackups, if you modify the files as given incolumn two.
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DayFiles
EditedType of
Backup
takenFiles contained in
the full backup
(Test
Folder_full_files.cb
u)
Files contained in the
differential backup (Test
Folder_dif_files.cbu)
Day 1 Full File A, File B, File Cand File D
Day 2 File A Differential File A, File B, File Cand File D (originalversions)
File A (modified version)
Day 3 File B Differential File A, File B, File Cand File D (original
versions)File A (version modified on
Day 2) and File B (version
modified on Day 3)
Day 4 File Band File
CDifferential File A, File B, File C
and File D (original
versions)File A (version modified on
Day 2), File B (version
modified on Day 4) and File
C (version modified on Day
4)
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Incremental backup
Copies only the files that have beenchanged since the last or lastincremental backup.
With incremental backup, you have thefull backup and one or more incrementalbackups.
The first incremental backup contains
changes since the last full backup. Each subsequent incremental backup
contains changes only since the previousincremental backup
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Example:
Let us take for example that you aretaking a full backup of a folder 'TestFolder'
containing Four files File A, File B, File C and File D on day 1
and have scheduled to take incrementalbackups of the folder on a daily basis.
The following table explains what wouldbe the contents of successive incrementalbackups, if you modify the files as given incolumn two.
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Day FilesEdited
Type of Backup
takenFiles contained in the full
backup (Test
Folder_full_files.cbu)
Files contained in
the incremental
backup (TestFolder_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(original versions)
File A (modified
version)
Day 3 File B Incremental File A, File B, File C and File D(original versions)
File B (modified
version)
Day 4 File Band File
CIncremental File A, File B, File C and File D
(original versions)File B (version
modified on Day 4)
and File C (version
modified on Day 4)
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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 thelast incremental backup.
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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 isgrowing quickly as the cost for thistechnology is falls.
CDP require little or no maintenance
where compared to other backupmethod. Many experts believes that CDP will
replace all other types of backup in the
future
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Backup Procedures
Continuous data protection providesautomatic data backup whenever data
is changed in an enterprise
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Backup procedures
Specify a regular plan of copying andstoring important data and program
files.
Generally, users should perform fullbackup 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.
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Backup procedures
Whatever backup procedures acompany adopts, they should be:
Stated clearly
Documented in writing Followed consistently
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Disaster recovery plan
A disaster recovery planis a writtenplan describing the steps a company
would take to restore computer
operations in the event of a disaster Contains four major components
Emergencyplan
Backupplan
Recoveryplan Test plan
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The emergency plan
Specifies the steps to be takenimmediately after a disaster strikes
The emergency plan usually is
organized by type of disaster, such asfire, flood, earthquake.
Depending on the nature and extent of
the disaster, the procedures that arefollowed in emergency will differ.
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The emergency plan
All emergency plans should contain thefollowing 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, powershutoff, file removal)
Employee evacuation procedures Return procedure that is who can reenter the
facility and what action they are to perform.
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The backup plan
Once the procedures in the emergencyplan have been executed, the next stepis to follow the back plan.
The backup plan specifies how anorganisation uses backup files andequipment to resume informationprocessing.
The backup plan should specify thelocation of an alternate computer facilityin the event the organizations normallocation is destroyed or unusable.
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The backup plan
When operations are so important thatthe organisation cannot afford to lose theoperation to a disaster, the organisationoften maintain a HOT SITE, which is a
separate facility that mirrors the systemsand operations of the critical site
The hot site always operate concurrently(Operating or acting in conjunction withanother.) with the main site, so that ifeither site become unavailable, the othersite continues to meet the organisations
needs
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The backup plan
The process of one systemautomatically taking the place of afailed system is called FAILOVER.
COLD SITE is a site that mirrors thecritical site, but does not becomeoperational until the critical sitebecomes unavailable.
When using a COLD SITE, some timeelapses between the disaster andwhen the cold site become functional.
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The backup plan
The backup plan identifies theseitems:
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
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The backup plan
For a backup plan to be successful,the organisation must backup all
critical resources
Also, additional people, includingpossible nonemployees, must be
trained in the backup and recovery
procedures because personnel couldbe injured in a disaster.
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The backup plan
The location of the alternate computerfacility is important.
It should be close enough to be
convenient, yet not so close that asingle disaster, such as earthquake
could destroy both the main and
alternate computer facilities
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The backup plan
Some organisation preinstall all thenecessary hardware, software andcommunication devices at thealternate computer facility.
These facilities immediately are readyin event of a disaster.
In other cases, the alternate computer
facility is simply an empty facility thatcan accommodate the necessarycomputer resources if needed.
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The backup plan
One more alternate computer is toenter into a RECIPROCAL BACKUP
RELATIONSHIP with another firm,
where one firm provides space andsometimes equipment to the other in
case of disaster.
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Recovery plan
Specifies the actions to be taken torestore full information processing
operations.
As with emergency plan, the recoveryplan differ for each type of disaster.
To prepare for disaster recovery, an
organisation should establishPLANNING COMMITTEES, with each
one responsible for different forms of
recovery.
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Recovery plan
For example, one committee is incharge of hardware replacement,
another is responsible for software
replacement.
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The Test Plan
Provide assurance that the disasterplan is complete, it should be tested
Disaster recovery test plan contains
information for simulating various levelof disasters and recording an
organisations ability to recover.
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The Test Plan
In a simulation, all personnel followthe steps in the disaster recovery plan.
Any needed recovery action that are
not specified in the plan should beadded.
Although simulation can be scheduled,
the best test of the plan is to stimulatea disaster without advance notice.
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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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