Areca Backup: A Free Delta Block Backup Program


Quick Summary:

  •  Simple clean interface
  • Backup simulation mode to preview a job before running it
  • Supports full, mirror, incremental, and differential backups, with optional delta block or image storage storage modes.
  • Zip or Zip 64 compressed archives with support for auto splitting.
  • AES 128/256 encryption at file system level
  • Include/Exclude filters
  • Unlimited pre and post processing tasks, with script support.
  • Archive explorer supports managing, deleting, searching, and restoring single files or whole archives.
  • Choice of command line control
  • Archive and file verification (SHA Hash Check)
  • Does not support volume shadow service copy (i.e. copying locked files)

Main Features:

Areca Backup is a free and open source backup software that sports a decent set of features. It has a simple clean gui, without a lot of flash.  Individuals who are new to backup software and backup terminology may have to spend a bit of time reading the online help manual finding out what each thing is for, and how it works. 

Areca supports the typical full, mirror, incremental, and differential backup methods with several additional “storage modes”  including a delta block mode.  For compressed archives it uses both Zip and Zip 64 with the choice of just about any encoding algorithm your heart desires.  It  allows you to place each backup in a single Zip archive, or a separate Zip for each file.  Zip archives can be automatically split at any size you choose. 

AES 128 or 256 encryption is supported, but Areca does not use zip encryption.  Instead it implements its own encryption at the file system access level.  This is an interesting feature that allows the same encryption layer even when compressed archives are not being used.

Areca supports any number of external pre and post-processing tasks you want to set up, but I feel it is a little light on the pre-made scripts it provides.   The file include/exclude filter is powerful enough to do most anything you want, but I find it a little clunker to use than I would like.

The main interface includes a very usable archive explorer which works well to manage, recover, and delete, archives.  You can also drill down into individual archives and extract a file from any backup point. There is also a built in search feature that facilitates finding individual files with in archives.

Areca does not include a built in scheduler, but it is fairly easy to use it with Windows own task scheduler.  All its functions can be controlled through the command-line, and the gui can be used to create ready made backup scripts. (Batch files in Windows)

Special Feature - Delta Backups:

The main feature in Areca that caught my attention was its ability to do delta block backups.  (For a detailed definition on delta backups see here.) I tested this feature extensively.  Tests were done using large text files, and making small changes, such as adding or deleting small amounts of text.  The delta feature worked as advertised and appears to operate in blocks as small as 2 kilobytes. After doing a series of delta backups, I restored the file from different backup points, and the various versions were perfectly reconstructed. 


Areca seems to work as advertised, and I did not find any glaring deficiencies.  It is one of the few free backup programs I have seen that will do delta backups.  My only concerns so fare are about the number of complaints I found in the forums in regards to backups sometimes taking very long times to finish, and backups failing to resume when doing ftp backups.  I did not experience the former problem even when testing it on very large amounts of data, but I did not test the ftp problem. I would use the encryption feature with caution since normal zip encryption is not used, you will only be able to open the encrypted archives using Areca.   This may not be a great program but it is a good program, and I think it fills an important niche with its delta block copy feature.

Areca Backup can be downloaded from the developers site here.

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