Differential backup: the smart alternative

Backing up company-relevant and customer-specific data has long since become a business success criterion. To decide on a form of backup that is right for your business, you first need to be clear about what data needs to be backed up, how often, and the worst-case downtime that could be afforded. If the backup is performed differentially, even frequent changes in data can be reliably backed up within short periods of time.


What is differential backup?

Differential backup is a method where changes are saved with respect to the last full backup. This means that a full backup is first saved to a disk. If changes are made shortly thereafter, these changes are backed up separately to another volume. If further changes are made, all the data that has changed since the last complete backup is saved in this way.

A differential backup means that all data is saved on one medium

A differential backup enables faster storage of relevant data and can reliably back up a large number of data changes. However, in order to implement such a differential backup, a high degree of storage capacity is required, since with each newly created backup, all data already stored since the last full backup is also backed up again. A certain amount of data redundancy is unavoidable


Distinction to other backup types

The simplest form of backup is the full backup or also the complete backup. Here, all existing data is backed up at the end of each specified period, for example on the Friday of a week. The disadvantage here is the high storage capacity required and the correspondingly large amount of time. In the event of a disaster, this method would only require the last backup. However, only this backup would be available.

A classic form of complete backup would be the generation or grandfather-father-son principle. In this case, backups of the entire existing data are made at different times. If a downstream backup („son”) is lost, the lost data can be restored from the information of the upstream backup („father”). Applied, this could mean that a full backup is created each day („son”), which is overwritten with the current data on the following days of the next week. On Friday, additional backups would be made of the entire week's events, which would remain unwritten („father”). On the last day of the month, a complete backup of all data created in the month in question would also be made, which would also be stored separately („Großvater”). After one month, the last weekly backup should be overwritten for the first time, and after one year, the monthly backup. Data stored one year before could thus be restored in case of loss. Unlike differential backup, generational backup intentionally creates long-term redundancy. More storage capacity is needed, which means more time is required.

@Another data backup concept is the incremental backup. Here, changes and adjustments are saved separately in shorter periods of time and until the next complete backup. In terms of a week, this means that a full backup would be created for the weekend. Changes occurring on the following Monday would be backed up using a hard disk. Changes occurring on Tuesday would again be on another disk, etc.

Differential backup would back up changes similarly, but without creating a separate backup for each day. On Monday, all of the day's customizations would be saved; on Tuesday, all of the changes that took place that day would be saved including the changes already backed up on Monday. On Wednesday, in addition to Wednesday events, Monday and Tuesday would be saved again, and so on until the end of the week. Whether a backup is incremental or differential depends on the importance and security classification of the data being backed up.While the incremental method would require both the last full backup and any change backups saved after that, if one has performed a differential backup, one would only need the last full backup and the last backup to enable data recovery. Moreover, if one is looking for a particular file, it will be quicker to find it on only 2 backups.


Consideration in an organization's backup strategy

A differential backup is particularly useful for companies that make frequent adjustments to data and want to keep it safe at all times.The security classification of the data to be backed up should therefore be clearly defined. Such data could be order data, for example. In addition, it must be clear how much space is available for storing the storage media and at what intervals the differential backup should take place (hourly, daily, weekly). It must also be clear when complete backups are to be performed. Depending on the data volume, it can be decided whether a differential backup is the best solution


Restore differential backup: How to do it?

If a differential backup is to be restored, the medium described with the differential backup must be compared with the last complete backup for this purpose.


Differential backup to tapes: Useful in the long run?

Magnetic tapes can store large amounts of data of about 3-4 terabytes. If their integrity is checked regularly, they are very safe and take up little space. They are less susceptible to mechanical stress than, for example, hard drives, but even tapes cannot withstand electromagnetic stress without damage. After 5-6 years, tapes need to be re-stored to prevent adverse effects due to declining magnetization.


Differential backup to external hard drive

For example, a differential backup should be saved to an external hard drive to prevent losses due to technical failures or access by unauthorized third parties. For smaller companies, it is also advisable to store backup media such as tapes and hard drives in bank lockers or similar. Larger companies can also make use of specially secured premises (cells).


Differential backup: dealing with the archive bit

Differential backup requires marking the data to be backed up by an archive bit. Such marking is done using a bit. By default, the data to be backed up is marked with a checkmark (bit) that initiates its backup. After the changed data has been backed up, the marking must be removed accordingly, so that only edited data is saved when the next backup is performed.


Langmeier Backup: the right solution for every business

Are you looking for a reliable and uncomplicated form of data backup and a corresponding software for your company? Langmeier offers various backup solutions for businesses. The tools offered by Langmeier are equally suitable for RAID data backup, the creation of an EDP backup copy or a Microsoft backup. The Business Package is a suitable data backup option for large companies but also interesting and usable as a backup solution for small businesses.

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About the Author , Free contributor
Charles Rahm Charles Rahm is a freelancer at Langmeier Software and is responsible for search engine optimization (SEO), among other things. Charles has a passion for travel. He lives in Bangkok and runs, among other things, the travel blog Sorglos Reisen. Sorglosreisen.Com

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