Introduction to Backup Types
Types of backup available to businesses empower them to draw their data backup strategy that focuses more on a. How to back up their organisation’s critical data their organisation’s critical data as a protection against data loss, b. At what frequency does the data need to be backed up, c. Where to store the backed up data local or onsite or offsite, d. How to restore the data if there is a disaster, e. Tools or methodologies to be used while back up as well as restoration, whether it is vendor-supplied tools or third-party tools or user-managed manual operation.
Several types of Backup
As mentioned above, the types of backup concentrate more on “how” to back up rather than “what” to backup. Therefore, let’s study various types of backup in detail.
1. Full backup
It is the most classical or conventional way of backing up the entire spectrum of data right from files, subfolders, folders at the system level or data files, redo logs, procedures, control files at the database level. The entire gamut of data will be backed up every time this full back up initiated.
Normally full backup of any system will be carried out as the first step before incremental or differential type of backup that happens subsequently. However, post several incremental/differential backups when fragmented segments become too unmanageable, starting a fresh cycle with a new full backup is advisable.
- A full backup is preferred in small setups where the consumption of backup storage is not that high.
- It is Easy and simple to manage full backups.
- Restoration is also easy and quick since it follows a straight and simple process.
- The latest media is sufficient to restore full backups
- It’s a slow and time-consuming process
- Consumption of storage space is quite high and results in a lot of duplication of data.
- System availability may be an issue to take frequent full backups.
2. Differential backup
This system involves backing up delta changes between the earlier full backup and current differential backup. Each time this backup is fired, the same process is repeated, which essentially means that files backed up in the earlier differential run in the cycle are also backed up, resulting in duplicates to some extent. Therefore, full backup media and the latest differential media are required to fully restore the system.
- It takes lower storage media when compared to full backup
- It is faster as it backs up only delta changes between earlier full backup and now
- More frequent backups can be planned since it involves the lower volume of data to be backed up
- Restoration is still faster when compared to incremental backup since it involves handling full backup media and the latest differential backup media.
- When compared to incremental backup
- It takes more storage space as it contains duplicates backed up in the earlier backups in the cycle.
- Backing up is also slower since it handles a larger volume
- When compared to full backup
- Restoration is a little complicated as it had to use full backup and one more media.
- The restoration takes more time for the above reason.
3. Incremental Backup
As in differential backup, a backup cycle starts with full backup and continues with multiple incremental backups. This system involves backing up incremental data created between the last backup and the current backup. For the first incremental backup, the last run is the full backup.
It isn’t easy this process through manual operation, and it is ideally managed through a vendor supplier tool or third party software.
- It consumes the lowest storage media spaces because the volume of data to be backed up is low, and there are no duplicates in the data to be backed up.
- Time taken for backup is also low due to the same above reason.
- Many frequent backups can be planned, say daily, twice daily.
- This system is used in database applications.
- Restoration of data is very cumbersome as it involves full backup media and the subsequent incremental backups in the current cycle.
- Restoration is also slower due to the above reason.
4. Mirror Backup
A mirror image of the source system is maintained in another system in an onsite or offsite location. The mirror image with the initial copy of the source system is automatically updated with changes in the source system at a frequent interval. If any files are wrongly removed from the source system, the same file would automatically get deleted in the mirror copy if it is not detected within the update interval. This mirror backup is mainly used to backup at the storage disk level,
Application Backup (Business Continuity Planning)
In this set-up, a copy of the source application platform (primary) is maintained on a different floor or building in the same location as secondary. An initial full copy of the primary application is installed at the secondary site, and further changes in the primary are updated in the secondary site in synchronous mode by the application. Thus, it protects primary applications from any disaster due to hardware failures, corruption of databases, software failure, and other internal failures.
In case of any disaster, the application can be switched over to a secondary site without losing much time, and business continuity can be ensured. Moreover, the primary system can be rectified later and restored. However, it does not cover other disasters like power break down or natural furies like floods, earthquakes, and cyclones, affecting primary/secondary sites.
In this model, the secondary site is maintained at an offsite location, and it is automatically updated at a frequent interval in an asynchronous mode. Therefore, it protects the primary site from natural disasters like floods, earthquakes, cyclones, political disturbances, etc.; the only issue in this model is primary and secondary sites should be interconnected with a high bandwidth network.
It is a highly contemporary setup in which the backup of the data is done in the cloud, and the application can be switched over to the cloud if there is any disaster. Many cloud service providers offer this service, and it will result in cost savings if used prudently.
With so many options available for backing up their data, businesses will have to choose that method that suits their data strategy and budget and maintains business continuity.
This is a guide to Backup Types. Here we discuss the types of backup concentrate more on “how” to back up rather than “what” to backup. You may also look at the following articles to learn more –