VM Backup Compression in NAKIVO Backup & Replication

In the modern world, the scope of data is growing at an astonishing rate. Modern businesses – particularly companies dealing with virtual environments – create vast amounts of VM backup data, which must be reliably stored and should take up as little space as possible. One of the most efficient ways to reduce your storage space is VM backup compression. NAKIVO Backup & Replication allows you to use different compression levels that suit your needs best. In this post, we walk you through using backup compression and explain the related benefits.

The Essence of Compression

Originating in 1977 as “LZ77”, data compression has been constantly studied and developed for over 40 years now. The history of compression has seen several different algorithms rise to popularity, such as DEFLATE, LZMA, or IMPLODE in 70s and 80s. ZIP, RAR, and many others appeared in 90s.

Data compression reduces file size by re-encoding the file data using fewer bits of storage in comparison with the original file. The compression process is based on mathematical equations – the software scans file data and looks for repeated patterns. Once all repeated patterns have been found, the compression software replaces instances of these patterns with smaller codes, indicating the locations where the pattern was found.

VM Backup Compression in NAKIVO Backup & Replication

In a virtual environment, data compression is normally used when performing VM backups. NAKIVO Backup & Replication applies built-in data compression, along with other data reduction techniques, achieving up to 10X storage space savings. However, to better illustrate the effectiveness of the data compression feature alone, we should disable those two other features.

In the General tab of the Inventory menu, we disable Skip swap files and partitions during processing.

All the other settings related to saving storage space must be selected at the repository creation step, under the Repositories tab. After creating the repository, they cannot be changed.

The second feature that complements compression is Deduplication. By default, deduplication is enabled; therefore, we should disable this feature, too.

As for the compression, NAKIVO Backup & Replication allows you to choose from several levels:

  • Fast: The lowest compression level. This is the fastest compression algorithm to run. Fast compression consumes less CPU, and the space savings should be sufficient for most cases.
  • Medium: The medium compression level. This compression algorithm is more complex. While requiring more CPU than the Fast level, Medium compression saves more space.
  • Best: The highest compression level that has an advanced compression algorithm. As Best compression uses more CPU than the Medium, this level is usually slower but saves much more space than the Fast level.
  • Disabled: Compression is completely disabled.

Let’s compare the results you can achieve with Fast and Best levels (the results that can be achieved with the Medium level should be in the range from Fast to Best).

First, let’s use the Fast compression setting to back up 48.4 GB of raw data:

  • Repository space usage: 20.2 GB
  • Fast compression result:  59.0% saved (29.0 GB)
  • Job duration: 17 minutes 53 seconds

Now we should back up the same 48.4 GB of raw data using the Best compression rate:

  • Repository space usage: 15.5 GB
  • Best compression result: 68.0% saved (33.0 GB)
  • Job duration: 33 minutes 58 seconds

As a control, we should now try to back up the same 48.4 GB of raw data with compression entirely disabled:

  • Repository space usage: 48.4 GB
  • As expected, the result of Disabled compression: 0.0% saved (0.0 GB)
  • Job duration: 20 minutes 27 seconds


Based on the results of the above demo, the Fast compression level gives you 29 GB, which amounts to almost 6.5 terabytes if calculated for 10 VMs over one month (29 GB x 10 VMs x 22 working days = 6,380 GB).

The Best compression level saves 33 GB, resulting in more than 7 terabytes per month for the same number of VMs (33 GB x 10 VMs x 22 working days = 7,260 GB).

Without VM backup compression, you can’t save anything (in our demo, the job without compression actually took more time than the Fast compression trial), and this can eventually result in additional cost for storage expansion.

Compression level Time Transferred RAW data (GB) Backup size Approximate space savings (GB) Approximate space savings (%)
Fast 17 min 53 sec 48.4 20.2 29.0 59
Best 33 min 58 sec 48.4 15.5 33.0 68
Disabled 20 min 27 sec 48.4 48.4 0.0 0.0

Now imagine that you have 20, 50, or even 100 VMs – the storage space you could save starts to add up!


Storage space always comes at a price. Data compression allows you to store more VM backups and efficiently reduce the costs of your storage. NAKIVO Backup & Replication has a well-proven data compression tool, ensuring significant cost reduction. Furthermore, when you combine data compression with NAKIVO Backup & Replication’s deduplication and omission of swap data, which were disabled for this test, you can achieve storage space savings of up to 10X. Download the Free Trial to test these powerful features in your own environment.


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