Introduction to Backup

Backup refers to the process of copying and archiving data so that it can be used to restore the original data after a data loss event.

Data Recovery is the process of restoring data that has been:

Lost
Mistakenly deleted
Corrupted
Rendered inaccessible

Backup Methods, Devices and Media

There are different backup methods that can be used depending on storage capacity, recovery requirements, and available resources.

The main backup methods are:

Full Backup
Incremental Backup
Differential Backup

1. Full Backup

A Full Backup involves making a complete copy of all selected data.

It provides the most comprehensive backup.

However, it requires:

More storage space
More time to complete
A larger backup window

Advantages of Full Backup

The main advantage is that restoring data is simple and quick because all required data is available in one complete backup.

Disadvantages of Full Backup

Takes more time to complete
Requires more storage space
Requires a larger backup window

2. Incremental Backup

An Incremental Backup copies only the data that has changed since the most recent backup.

The previous backup may have been:

A full backup
Another incremental backup

Incremental backups save both:

Storage space
Backup time

However, multiple backup sets may be required to completely restore the data.

3. Differential Backup

A Differential Backup copies all changes made since the last full backup.

Unlike incremental backup, differential backup does not require every previous differential backup for restoration.

However, differential backups use more storage space over time compared to incremental backups.

Types of Storage Devices

The storage device used to hold backup data is an important part of a backup strategy.

Common backup storage devices include:

External Hard Disk Drive
Solid-State Drive
USB Flash Drive
CD
DVD
Online or Cloud Storage

External Hard Disk Drive (HDD)

An External Hard Disk Drive (HDD) provides a large amount of storage capacity at a relatively low cost.

It uses spinning magnetic disks to store data.

External HDDs are suitable for:

Backing up large amounts of data
Transferring files between computers
Long-term data storage

Solid-State Drive (SSD)

A Solid-State Drive (SSD) uses flash memory to store data.

SSDs provide faster read and write speeds than HDDs.

They are also more resistant to physical shock and consume less power.

Advantages of SSD

Faster performance
Faster read/write speed
Lower power consumption
Better resistance to physical shock
Suitable for portable devices

SSDs are generally more expensive per gigabyte than HDDs.

They are suitable for tasks requiring higher speed, such as:

Running operating systems
Accessing frequently used data

USB Flash Drive

A USB Flash Drive is a small and portable storage device.

It is also known as:

Thumb Drive
USB Stick

USB flash drives use flash memory and connect to computers through USB ports.

They are convenient for:

Transferring small amounts of data
Carrying files between devices
Portable storage

CD Technology

CD stands for Compact Disc.

A CD is an optical storage device that uses laser technology to read and write data on a reflective surface.

CDs provide relatively low storage capacity compared with modern storage devices.

They are commonly used for:

Software distribution
Music
Multimedia content
Data storage

DVD Technology

DVD stands for Digital Versatile Disc.

DVDs are similar to CDs but provide higher storage capacity.

They are commonly used for:

Movies
Software
Large files
Backups

Common DVD formats include:

DVD-R
DVD+R
DVD-RW
DVD+RW

These formats provide different levels of compatibility and rewritability.

Online Storage or Cloud Storage

Online Storage, also known as Cloud Storage, stores data on remote servers that are accessed through the internet.

Cloud storage allows users to access data from different locations where an internet connection is available.

It also provides off-site backup, which can improve data protection.

Examples mentioned in the notes include:

Dropbox
Google Drive
Microsoft OneDrive
iCloud

Backup Scheduling and Media Rotation System

Backup scheduling and media rotation systems are important parts of a strong backup strategy.

They help ensure:

Data protection
Backup availability
Recovery readiness

Backup Scheduling

Backup Scheduling determines when and how frequently backups should be performed.

The backup frequency depends on factors such as:

Rate of data change
Business requirements
Available resources
Importance of the data

Common backup frequencies include:

Daily
Weekly
Monthly
Real-time backup for critical systems

Schedule Backups During Off-Peak Hours

Backups should preferably be scheduled during periods of low system usage.

This helps reduce disruption to normal operations.

Important factors include:

System usage patterns
Network traffic
Available system resources

Backup Retention Period

A retention period determines how long backup data should be kept.

The retention period may depend on:

Regulatory requirements
Business requirements
Available storage capacity

An example retention strategy may include:

Daily backups retained for one week
Weekly backups retained for one month
Monthly backups retained for one year

Backup Window

A specific period should be allocated for backups to complete.

The backup process should ideally not interfere with:

Critical processes
System maintenance
Normal business operations

Backup Priority

Different types of data and systems can be assigned different priorities.

Critical data should generally be:

Backed up more frequently
Given higher priority

Media Rotation System

A Media Rotation System involves rotating different backup media according to a schedule.

Backup media may include:

Tapes
Disks
Cloud storage

Each storage medium has different characteristics related to:

Cost
Durability
Accessibility

Purpose of Media Rotation

Media rotation helps:

Distribute wear and tear
Reduce the risk of media failure
Improve redundancy
Maintain multiple generations of backup

Grandfather-Father-Son (GFS) Rotation

The Grandfather-Father-Son (GFS) method is a popular backup media rotation system.

It commonly uses:

Son: Daily backups

Father: Weekly backups

Grandfather: Monthly backups

This allows backup sets of different ages to be maintained.

Custom Media Rotation

Organizations may design their own rotation pattern depending on factors such as:

Data volume
Backup frequency
Retention requirements
Available storage

Off-Site Storage

Backup media should also be stored off-site.

Off-site storage helps protect backup data against disasters such as:

Fire
Flood
Theft

Backup media can be rotated between:

On-site storage
Off-site storage

Verify Backup Media

Backup media should be checked regularly.

Organizations should also perform test restores.

This helps ensure:

Backup integrity
Data recoverability
Problems are identified before an actual data-loss event

Introduction to RAID

RAID stands for Redundant Array of Independent Disks.

RAID is a technology used to combine multiple physical disk drives into a single logical unit.

RAID may be used for:

Data storage
Performance improvement
Data reliability
Fault tolerance

RAID systems can provide better reliability or performance compared with a single disk configuration.

RAID Levels

There are several RAID levels.

Each RAID level provides a different combination of:

Performance
Redundancy
Fault tolerance
Storage capacity

Common RAID levels include:

RAID 0
RAID 1
RAID 5
RAID 6
RAID 10

RAID 0 – Striping

RAID 0 uses striping without redundancy.

Data is distributed across multiple disks.

This can increase read and write performance.

Features of RAID 0

High performance.
Zero capacity loss.
Zero fault tolerance.
Good read and write performance.

RAID 0 does not provide redundancy.

Therefore, failure of a disk may result in data loss.

RAID 1 – Mirroring

RAID 1 uses mirroring.

Data is duplicated across multiple disks.

This provides redundancy because copies of the same data are stored on different drives.

According to the provided notes, RAID 1 provides redundancy but does not necessarily improve performance.

RAID 5

RAID 5 uses:

Striping
Distributed parity

Data and parity information are distributed across all disks in the array.

RAID 5 provides a balance between:

Performance
Storage efficiency
Fault tolerance

RAID 6

RAID 6 is similar to RAID 5 but uses additional parity information.

This provides increased fault tolerance.

RAID 6 can withstand the failure of two disks at the same time.

RAID 10

RAID 10, also known as RAID 1+0, combines:

Mirroring
Striping

Data is first mirrored across disk pairs and then striped across those mirrored pairs.

RAID 10 provides:

High performance
Fault tolerance

However, it requires a larger number of disks.

Different Types of Data Recovery Systems

Organizations and enterprises use different types of data recovery systems to recover lost data.

Before choosing a recovery system, an organization should first evaluate:

Importance of data
Importance of systems
Recovery requirements
Business requirements

After assessing the data and systems, an appropriate recovery system can be selected.

Common types of data recovery systems include:

Bare Metal Recovery
Online Disk Backup
Continuous Data Protection

Bare Metal Recovery

Bare Metal Recovery involves backing up the complete computer system.

This may include:

Operating system
Software applications
Data
System settings

In the event of data loss, bare metal recovery can restore the complete system.

It can reduce recovery time because the operating system, software, data, and settings can be recovered together.

Without this type of recovery, it may be necessary to:

Reinstall the operating system.
Reinstall software applications.
Restore data.
Restore system settings.

Bare metal recovery can simplify this process.

Online Disk Backup

Online Disk Backup is suitable for data that changes regularly.

Frequently changing data can be backed up more often.

Online disk backup systems may provide a tiered recovery architecture.

This can give organizations greater flexibility by allowing:

Frequent backups of important data
Less frequent backups of less important data

Continuous Data Protection

Continuous Data Protection (CDP) is also known as Continuous Backup.

It is designed to reduce recovery time.

Continuous Data Protection can back up data to:

A local area network
An off-site location

Both backup destinations may be used at the same time.

If an organization experiences data loss at its local site, the off-site backup can be used for recovery.

Features of Continuous Data Protection

A continuous data protection system may also maintain a log of data changes made since the previous backup.

This helps maintain updated recovery information.

According to the provided notes, CDP can:

Be installed relatively easily
Use multiple backup locations
Maintain records of data changes
Provide minimal recovery time when disk storage is used