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What is a Backup?
• Backup is an additional copy of data that can be
used for restore and recovery purposes.
• The Backup copy is used when the primary copy
is lost or corrupted.
• This Backup copy can be created as a:
– Simple copy (there can be one or more copies)
– Mirrored copy (the copy is always updated with
Backup and Recovery Strategies
Several choices are available to get the data
to the backup media such as:
• Copy the data.
• Mirror (or snapshot) then copy.
• Remote backup.
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It’s All About Recovery!
• Businesses back up their data to enable
its recovery in case of potential loss.
• Businesses also back up their data to
comply with regulatory requirements.
• Types of backup derivatives:
– Disaster Recovery
– Archival
Differences Between Backup / Recovery &
Archive
Data typically maintainedfor analysis, value generation, or compliance
Data typically overwritten on periodic basis (e.g., monthly)
Useful for compliance and should take into account
information-retention policy
Not for regulatory compliance— though some are forced to use
Typically long-term (months, years, or decades)
Typically short-term (weeks or months)
Adds operational efficienciesby moving fixed / unstructured content out of operational environment
Improves availability by enabling application to be restored to a specific point in time
Available for information retrieval
Used for recovery operations
Primary copy of information A secondary copy of information
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Reasons for a Backup Plan
• Hardware Failures
• Human Factors
• Application Failures
• Security Breaches
• Disasters
How does Backup Work
Disk Storage Tape Backup Data Set Metadata Catalog Backup Server & Storage Node8
Business Considerations
• Customer business needs determine:
– What are the restore requirements – RPO & RTO?
– Where and when will the restores occur?
– What are the most frequent restore requests?
– Which data needs to be backed up?
– How frequently should data be backed up?
• hourly, daily, weekly, monthly
– How long will it take to backup?
– How many copies to create?
Data Considerations: File
Characteristics
• Location
• Size
• Number
• Data Compression
– Application binaries – do not compress well.
– Text – compresses well.
– JPEG/ZIP files – are already compressed and expand
if compressed again.
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Data Considerations: Retention
Periods
• Operational
– Data sets on primary media (disk) up to the point
where most restore requests are satisfied, then
moved to secondary storage (tape).
• Disaster Recovery
– Driven by the organization’s disaster recovery policy
• Portable media (tapes) sent to an offsite location / vault. • Replicated over to an offsite location (disk).
• Backed up directly to the offsite location (disk, tape or emulated tape).
• Archiving
Database Backup Methods
• Hot Backup: production is not interrupted.
• Cold Backup: production is interrupted.
• Backup Agents manage the backup of
different data types such as:
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Backup Granularity and Levels
Full Backup
Cumulative (Differential)
Incremental
Restoring an Incremental Backup
Files 1, 2, 3, 4, 5 Production Production Incremental Incremental Tuesday File 4 Incremental Incremental Wednesday File 3 Incremental Incremental Thursday File 5 Files 1, 2, 3 Monday Full Backup Full Backup• Key Features
– Files that have changed since the last full or incremental backup are backed up.
– Fewest amount of files to be backed up, therefore faster backup and less storage space.
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Restoring a Cumulative Backup
Files 1, 2, 3, 4, 5, 6 Production Production Cumulative Cumulative Tuesday File 4 Files 1, 2, 3 Monday Full Backup
Full Backup CumulativeCumulative
Wednesday Files 4, 5 Cumulative Cumulative Thursday Files 4, 5, 6
• Key Features
– More files to be backed up, therefore it takes more time to backup and uses more storage space.
Backup Architecture Topologies
• There are 3 basic backup topologies:
– Direct Attached Based Backup
– LAN Based Backup
– SAN Based Backup
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Direct Attached Based Backups
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SAN Based Backups (LAN Free)
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Backup Media
• Tape
– Traditional destination for backups
– Sequential access
– No protection
• Disk
– Random access
Multiple Streams on Tape Media
Tape
Tape
Data from
Stream 1 Data from
Stream 2 Data from Stream 3
• Multiple streams interleaved to achieve higher throughput on
tape
– Keeps the tape streaming, for maximum write
performance
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Backup to Disk
• Backup to disk minimizes tape in backup
environments by using disk as the primary
destination device
– Cost benefits
– No processes changes needed
– Better service levels
Tape versus Disk – Restore
Comparison
*Total time from point of failure to return of service to e-mail users 0 10 20 30 40 50 60 70 80 90 100 110 120
Recovery Time in Minutes* Tape Backup / Restore Disk Backup / Restore 108 Minutes 108 Minutes 24 Minutes 24 Minutes