65528: Acronis Cyber Protect Cloud, Acronis Cyber Backup: Why incremental backup looks like full backup

Last update: Wed, 2020-08-19 09:31

Symptoms

During exploring content of archive you can see that size of Incremental backup is comparable or even higher that Full backup.

For example, check full backup size:

And compare it with the size of a subsequent Incremental backup:

 

Cause

Issue is caused by peculiarities of Recovery point size calculation. The number displayed as "Size" of a recovery point is NOT the actual size of this recovery point but an intermediate number.

When saving data to Archive 12 format, Acronis Agent uses the following methods to reduce data size: compression and subsequent deduplication..

  • Compression – the process of reducing the size of a data file exploiting statistical redundancy to represent data without losing any information. Archive 12 uses Zstandard algorithm to perform data compression https://en.wikipedia.org/wiki/Zstandard
  • Deduplication - whereas compression algorithms identify redundant data inside individual files and encodes this redundant data more efficiently, the intent of deduplication is to inspect large volumes of data and identify large sections of files (in case of Archive 12 data chunks sizes may vary from 64kb to 512kb) – that are identical, and replace them with a shared copy. More information can be found here https://en.wikipedia.org/wiki/Data_deduplication

The number shown as the recovery point size is the size of data read (from the source system) after compression is performed.

Solution

Pay attention to the entire backup size. In case you need to find the size of a particular slice, check the Activities section for this backup plan.

For example, the real size of data written during Full backup is 1.54 TB: 

Real size of incremental backup is 286 GB:

 

 

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