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27-June-2017

Choosing a Compression Format

D_back provides several formats for compressing files that you add to backup. The most suitable format depends on types of files, size of data, amount of time for processing. The program supports No Compression, Native Zip Compression, 7-zip Compression, and other compression formats.
  • No Compression. This option provides copying files without any compression from source to the destination backup directory.
  • Native Zip Compression. This is the fastest zip compression (default compression type), which packs all source files to standard .zip file. Zip is most suitable for archiving large quantities of mixed types of data, when speed is more important than maximum compression. The program supports Zip64 extension of standard Zip format. Zip file, any compressed or source file can be larger than 4Gb. Zip archive can contain more than 65535 files.

  • 7z Compression. The slow compression method. The main advantage is a highest compression ratio especially on a lot of small files. 7z uses LZMA compression, you system must have at least 1 GB memory to use this method. The program packs all source files to a single .7z file. The backup file is fully compatible with the free 7-zip file archiver.

Using external file compresson tools

You can use any archiving utility as plug-in which meets the following requirements:
  • The compression tool should be installed on your computer;
  • This program should have the command-line interface and should be able to create archive by using a simple text file with the list of files to be archived.

If external file archiver meets this cases, then the plugging in is quite simple. All config options are located in compressors.xml file, so you can view and edit it (if necessary) by any text editor without any problem. Here is the list of external archivers which have been tested as plug-ins:

  • WZZIP (Command Line Support Add-On to WinZip)
  • RAR (Command Line Support Add-On to Winrar)
  • 7-zip

Comparison of archive formats

We tested various compression methods on compression ratio and time. The test was made by D_back version 1.69.19 on computer with processor Intel Core I3@3.3GHz, 4Gb Ram. To evaluate compression we prepared 3 temporary directories with various files: .exe|.dll, .doc|.xls and .html files. The results of testing are listed below:

Executable files (.exe,.dll)     Total Files:10315     Total Size:5.3Gb
Format Compression time (min) Size of compression File Compression ratio
No compression 03:08 5.3Gb 1
Zip 08:21 2.2Gb 2.37
Rar (external Winrar 5.1) 07:04 1.86Gb 2.9
7z (LZMA) 16:41 1005Gb 5.42


Microsoft Office files (.doc,.xls)     Total Files:25313     Total Size:4.3Gb
Format Compression time (min) Size of compression File Compression ratio
No compression 02:40 4.3Gb 1
Zip 06:27 2.5Gb 1.72
Rar (external Winrar 5.1) 07:04 2.4Gb 1.79
7z (LZMA) 16:41 1.1Gb 3.91


HTML text files (.html)     Total Files:17589     Total Size:1.2Gb
Format Compression time (min) Size of compression File Compression ratio
No compression 06:07 1.2Gb 1
Zip 02:17 320Mb 3.94
Rar (external Winrar 5.1) 02:32 285Mb 4.43
7z (LZMA) 11:11 177Mb 7.12

When speed is more important than maximum compression you should use Zip compression. Zip is very fast, and sometimes backing up in zip is faster than simply copying. In other case 7z will be the best choice. 7z provides higher compression than Zip and Rar, but it is more CPU intensive and need at least 1 Gb RAM.

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