Areca Backup
Please read Areca's FAQ before submitting issues or feature requests !

About Areca


End user documentation


Technical informations


Misc



Copyright (c) 2024-2025 bugtamer
Copyright (c) 2005-2023 Olivier PETRUCCI

Features :

How to automate backups ?
You can use Areca's command-line interface to create backup scripts (*.bat or *.sh scripts), and schedule their execution with Linux's crontab or Windows' scheduler.
Windows scheduling : http://support.microsoft.com/kb/308569
Linux scheduling : http://en.wikipedia.org/wiki/Cron


Does Areca support Volume Shadow Copy Service (VSS) on Windows ?
No, Areca doesn't support VSS, but you can use the ArecaVSS plugin (www.arecavss.com), which will add VSS support to Areca.
This will allow Areca to read and store files that are locked by the system or programs (such as outlook *.pst files)


How does Areca detect modified or new files when incremental backups are chosen ?
Areca uses the file's size and last modification time to detect modified files. If one of these attributes is modified (whatever its value is), the file is flagged as modified.
Since v7.2.17, Areca can also inspect the file's content to detect modifications of its content (which is much slower than detection based on attributes)


Can Areca store backups on FTP servers ?
Yes - since v4.5, Areca can store your files on FTP servers.
If FTP storage is used, it is highly advisable to compress your archives. (You can use zip64 or standard zip compression)
It is also advisable to use the "FTP Test" feature (which can be found on the FTP parameters window) to check that your FTP server is compatible with Areca.


Can Areca store backups on FTPs (File Transfer Protocol over SSL/TLS) servers ?
Yes - since v4.5.1, Areca can store files on FTPs servers.
Areca supports SSL and TLS, as well as implicit and explicit modes.


Can Areca store backups on SFTP servers ?
Yes - since v7.2, Areca can store files on SFTP servers.


Can Areca burn CDs/DVDs ?
No, Areca can only store your backups on your file system (ie local or remote directories)


When can I use compressed targets ?
You can use standard zip compression if your archives will be smaller than 4GB. For bigger archives, use zip64 compression.
Of course, it is useless to use compression when your source files are already compressed (for instance JPG, MP3, AVI files) : No space will be gained and it will result in unnecessary time consumption during backup.


Why does Areca not use zip encryption for encrypted compressed archives ?
Areca supports encryption, but it is implemented at the file system access level (ie it is not implemented as zip encryption). This allows to benefit from the same encryption layer, whether the target is compressed or not.
In other words, if you choose target encryption and compression, Areca will encrypt the archives exactly the same way as if you choose target encryption without compression.

ACL and Extended attributes support :

Does Areca support ACL and extended attributes ?
Yes : since version 7.0, Areca supports ACL and extended attributes on Linux.
This feature uses native code (unlike Areca's backup engine, which has been written in Java) and is currently compiled for 64 and 32 bits Linux systems with glibc 2.35.
Note that this native code needs the "acl" library.

Example on how to find the GNU C Library (GLIBC) version on your operative system (if you need to know) :

$ locate libc.so
/lib32/libc.so.6
/usr/lib/i386-linux-gnu/libc.so.6
/usr/lib/x86_64-linux-gnu/libc.so
/usr/lib/x86_64-linux-gnu/libc.so.6

Execute glibc :

$ /usr/lib/x86_64-linux-gnu/libc.so.6
GNU C Library (Ubuntu GLIBC 2.35-0ubuntu3.9) stable release version 2.35.
[...]



How can I activate ACL and extended attributes support ?
ACL and extended attributes support are not enabled by default. You have to modify your configuration to activate it.
Open the "fwk.properties" file which is located in Areca's configuration subdirectory and set the "filesystem.accessor.impl" to "com.myJava.file.metadata.posix.jni.JNIMetaDataAccessor" (the default value is "com.myJava.file.metadata.posix.basic.DefaultMetaDataAccessor")
On startup, Areca displays some information about the "filesystem accessor" which is used (you should see something like "Loading configured file metadata accessor : [com.myJava.file.metadata.posix.jni.JNIMetaDataAccessor]" in your log file or log tab)

Example :

Edit areca-backup/config/fwk.properties and replace

filesystem.accessor.impl = com.myJava.file.metadata.posix.basic.DefaultMetaDataAccessor

with

filesystem.accessor.impl = com.myJava.file.metadata.posix.jni.JNIMetaDataAccessor

Notes :

  • A line that starts with # is ignored by Areca.
  • Only one filesystem.accessor.impl = line is allowed.


How to fix symbol lookup error: libarecafs.so: undefined symbol: acl_get_file

It happens at launch time (areca.bat or areca.sh).

Example :

openjdk version "x.y.z" yyyy-mm-dd LTS
OpenJDK Runtime Environment Vendor-x.y.z (build x.y.z-LTS)
OpenJDK 64-Bit Server VM Vendor-x.y.z (build x.y.z-LTS, mixed mode, sharing)
/path-to/java/bin/java: symbol lookup error: /path-to/areca-backup/lib/libarecafs.so: undefined symbol: acl_get_file
You may need to recompile libarecafs.so in your system.


How can I compile Areca's library that handles ACL and extended attributes ?
That's quite simple : download Areca's sources on SourceForge (zip file available on the download page), uncompress it, open the "jni" directory and run the "compile.sh" script.
It will create a "libarecafs.so" file. Copy this file in Areca's "lib" directory.

You can also build a brand new Areca release with your glib and JDK versions presents in your systems by running (from the root of Areca Backup source code directory) :

  • ant linux-x86-64
  • ant linux-x86-32

These commands require GCC, JDK and Apache Ant installed in your system.




How to fix yy-mm-dd hh:mm - INFO - ACL support : no
This message is shown in the Log tab. Log example : 
[...]
yy-mm-dd hh:mm - WARNING - com.myJava.file.metadata.posix.jni.JNIMetaDataAccessor cannot be used on this system. Got the following error : "java.lang.UnsatisfiedLinkError : no acl in java.library.path: /path-to/areca-backup/lib/:/lib64:/lib:/usr/lib64:/usr/lib:/usr/lib64/java:/usr/lib/java:/usr/lib64/jni:/usr/lib/jni:/usr/share/java"
yy-mm-dd hh:mm - WARNING - You should check that the 'acl' package is properly deployed on your computer.
In most cases, there should be a 'libacl.so' file or symbolic link somewhere on your filesystem.
If it is not the case, you should check for a 'libacl..so' file and create a symbolic link named 'libacl.so' on it.
If no such file can be found, just install the 'acl' package using your standard package manager.
yy-mm-dd hh:mm - WARNING - [com.myJava.file.metadata.posix.jni.JNIMetaDataAccessor] not validated. The default metadata accessor will be used instead. See FAQ for more informations about file metadata management. (ACL & extended attributes)
[...]
yy-mm-dd hh:mm - INFO - ACL support : no
yy-mm-dd hh:mm - INFO - Extended attributes support : no
[...]

Create a symbolic link to allow Areca to find the libacl.so :

areca-Backup $ ln -s </path-to/libacl.so> ./lib/libacl.so

Example :

$ ldconfig -p | grep libacl
        libacl.so.1 (libc6,x86-64) => /lib/x86_64-linux-gnu/libacl.so.1
        libacl.so (libc6,x86-64) => /lib/x86_64-linux-gnu/libacl.so

So the command line in this example will be :

areca-Backup $ ln -s /lib/x86_64-linux-gnu/libacl.so ./lib/libacl.so


Problems :

'java.io.IOException: The system cannot find the file specified' on remote directories
This error can occur when you store your backups on a remote directory (over a network) which is not available (network error).


I get errors when I try to store archives on a FTP server - Why ?
Areca needs extended accesses to the FTP storage directory in order to use it.
More precisely, the FTP user must be granted to following rights :
- Read / Write / Delete / Create / Rename on files
- List / Create / Delete / Rename on subdirectories

Areca has been tested with the following FTP servers :
- Linux : ProFTPD and VSFTPD
- Windows : FileZilla FTP Server, TypSoft FTP Server, Cerberus FTP Server and zFTP Server

Note that - depending on the FTP server configuration - file sizes can be restricted (for instance, files over 1GB won't be accepted)


I get errors when trying to use FTP over SSL or SFTP - Why ?
Solution proposal (special thanks to "Mirkosoft") :
"I could solve my issue with ftp timeouts: the problem was the firewall built into windows.
(The following is valid for windows 7 ultimate on a 64 bit system. Not approved on other systems)

As mentioned, I'm using ftp over ssl.
The windows firewall tries to perform stateful inspection on ftp traffic. Using ssl, this traffic becomes unreadable to the firewall and thus the connection is interrupted after about 10 minutes or so.

There are two possible solutions to this:
1. Disable the windows firewall completely.
Not recommend for most users.

2. Disable stateful inspection on ftp traffic using the command line.
This may be achieved by calling netsh advfirewall set global StatefulFtp disable

The state of ftp inspection may be checked by calling netsh advfirewall show global Statefulftp
This solves all of the mentioned timeout problems for me."