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All about DATA backups & rotation

DATA backup is to make copies of particular data in order to use those copies for restoring the information if a failure occurs (a data loss event due to deletion, corruption, theft, viruses etc.).

there are four common backup types implemented and generally used in most of these programs: full backup, differential backup, incremental backup and mirror backup.

backup-types

  • Full backup

Full back up is the starting point for all other types of backup and contains all the data in the folders and files that are selected to be backed up.

 

  • Differential backup

Differential backup contains all files that have changed since the last FULL backup. The advantage of a differential backup is that it shortens restore time compared to a full back up or an incremental backup.

 

  • Incremental backup

Incremental backup stores all files that have changed since the last FULL, DIFFERENTIAL OR INCREMENTAL backup. The advantage of an incremental backup is that it takes the least time to complete.

 

  • Mirror backup

Mirror backup is identical to a full backup, with the exception that the files are not compressed in zip files and they cannot be protected with a password. A mirror backup is most frequently used to create an exact copy of the source data.

 

  • Smart backup

Smart backup is a backup type which combines the full, differential and incremental backup types with cleanup operations in order to efficiently manage the backups according with the backup settings and the free disk space in destination. The Smart backup type starts with a full backup.

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Tape Rotation

A good tape rotation schedule is vital to ensure data recovery. The best rotation schedule is one that provides you with a long and varied history of file versions.

Grandfather-Father-Son Backup Scheme

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This is the most commonly used media rotation schedule. This scheme uses daily (Son), weekly (Father), and monthly (Grandfather) backup sets. Four backups tapes are labeled for the day of the week each backs up.

Tower of Hanoi Backup Scheme

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The Tower of Hanoi rotation schedule is widely used. In this schedule, one tape set “A” is used every other backup session (daily sessions in this example). Start Day 1 with “A” and repeat every other backup session (every other day). The next tape set “B” starts on the first non- “A” backup day and repeats every fourth backup session. Media set “C” starts on the first non-“A” or non- “B” backup day and repeats every eighth session. Media set “D” starts on the first non-“A”, non-“B”, or non-“C” backup day and repeats every sixteenth session. Media set “E” alternates with media set “D”.

What is RTO, RPO, WRT, MTD ?

When it comes to Disaster Recovery & High Availability Techniques, these Acronyms are a must. So will discuss a bit in further.

1. Business as usual

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At this stage all systems are running production and working correctly.

2. Disaster occurs

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On a given point in time, disaster occurs and systems needs to be recovered. At this point the Recovery Point Objective (RPO) determines the maximum acceptable amount of data loss measured in time.

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3. Recovery

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At this stage the system are recovered and back online but not ready for production yet. The Recovery Time Objective (RTO) determines the maximum tolerable amount of time needed to bring all critical systems back online.

4. Resume Production

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At this stage all systems are recovered, integrity of the system or data is verified and all critical systems can resume normal operations. The Work Recovery Time (WRT) determines the maximum tolerable amount of time that is needed to verify the system and/or data integrity. This could be, for example, checking the databases and logs, making sure the applications or services are running and are available.

5. Resume Production – Scenario

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The sum of RTO and WRT is defined as the Maximum Tolerable Downtime (MTD) which defines the total amount of time that a business process can be disrupted without causing any unacceptable consequences.