Areca Backup

Areca Backup was an Open Source personal file backup software developed in Java. It was released under the GNU General Public License 2.

Features

Areca Backup included a backup engine, as well as a graphical user interface and a command-line interface.
The application included the following features:

ZIP/ZIP64 compression
AES 128 & AES 256 encryption
Backup filters
Incremental backup, differential and full backup support
Delta backup
Archives merges
As of date recovery
Transaction mechanism for all critical processes to guarantee backups' integrity
Unix file permissions backup/recovery
E-Mail reports
Backup simulation
FTP and FTPS support
SFTP support

Areca also provided all tools needed to handle your archives:

Backup
Archive recovery ; entire archives or single files can be easily recovered
Archive merge: contiguous incremental archives can be merged into a single archive to save storage space
Archive deletion
History explorer: different versions of a given file can be browsed and restored
Archive explorer: files can be searched among your archives

Storage modes
Areca could handle multiple storage modes:

Standard: It is the default mode, which is recommended for most users: If you choose this storage mode, a new archive will be created for each backup. All new or modified files since the last backup will be stored in this archive.
Delta: This mode is recommended for advanced users only: If you choose this storage mode, a new archive will be created for each backup. All modified *parts* of files since the last backup will be stored in this archive. This mode is particularly useful if you are handling large files.
Image: If you choose this storage mode, a unique archive will be created and updated at each backup.

Backup types
Areca could handle the following types of backups:

Full Backup: When a full backup is performed, ALL files are stored in your archive.
Incremental backup: When an incremental backup is performed, only the files which have been modified since the last backup are stored in your archive.
Differential backup: When a differential backup is performed, only the files which have been modified since the last FULL backup are stored in your archive.

Areca used the file's size and last modification time to detect modified files. If one of these attributes is modified, the file is flagged as modified. This allows a fast detection of modified files.
Areca was downloadable pre-packaged for Linux and Windows 2000/Windows XP and Windows Vista. But it also ran on any other operating system, provided that a Java Runtime Environment has been installed. It was translated to: Chinese, Chinese, Czech, Danish, Dutch, English, French, German, Hungarian, Italian, Japanese, Russian, Spanish, Swedish.

Limitations

Areca Backup did not have a built in method of handling automated backup creation for Windows-based operating systems. The user is required to configure a backup strategy using an included Wizard, which consequently creates a collection of bat files required to be manually added to the Windows Task Scheduler.
Areca Backup did not support VSS and cannot backup files that are locked by other programs, but there are plugins for Areca that do