Dar is an extremely versatile and powerful tool
and DarGUI is not planned to be a means of accessing
all its features. Instead, DarGUI is intended to simplify the most
common tasks
of making backup archives and restoring files from these and
to provide a small number of additional features. DarGUI
provides the following features:
Many of these descriptions are copied from Denis
Corbin's FEATURES document.
- Filters
-
DarGUI is able to backup everything from a single file to
an entire filesystem. Additionally a mechanism of filters enables the
inclusion or exclusion of individual files or directories
while backing up or restoring a directory tree. (back to top)
- Differential backup
-
When making a backup with DarGUI, you have the option of
making a full backup or a differential backup. A full backup, as
expected, makes a backup of all files as specified on the command line
(with or without filters). A differential backup, however, saves only
files that have changed since a given reference
backup. Additionally, files that existed in the reference backup and
which do not exist anymore at the time of the differential backup are
recorded in the backup. At recovery time, (unless you deactivate it),
restoring a differential backup will update changed files and new
files, but also remove files that have been recorded as deleted. Note
that the reference backup can be a full backup or another differential
backup. This way you can make a first full backup, then many
differential backup, each taking as reference the last backup made. (back
to top)
- Slices
-
DarGUI
can split an archive over several removable media
whatever their number is and whatever their size is. Archives produced
by DarGUI can be saved onto floppy disk, CD-R, DVD-R, CD-RW,
DVD-RW, Zip,
Jazz, etc... Given the desired size, Dar will split
the archive into several files (called SLICES). DarGUI can also backup
data to one slice of any size. When restoring files, DarGUI will simply
pause and prompt the user for the location of a missing slice.
It is important to remember, however, that older versions of dar need to be
able to examine both the first and last slices of a set in order to get
a listing of its contents. For this reason, when storing archives on DVD, CD or
similar media consider using the method described in the note about using slices.
(back
to top)
-
- Compression
-
DarGUI can use compression using the gzip, bzip2, lzo or xz
algorithms. Note that compression is done before slices are
created, which means that using compression with slices will not make
slices smaller, but will probably result in the backup being contained
in fewer slices. (back
to top)
- Selective compression
-
DarGUI can be use filters to determine which
files will be compressed. This way you can speed up the backup
operation by not trying to compress *.mp3, *.mpg, *.zip, *.gz and other
already compressed files. Another setting allows you to prevent files
under a given size (whatever their name), from being
compressed. (back
to top)
- Direct access
-
Even using compression Dar does not have to read the
entire backup to extract one file. This way if you just want to restore
one file from a huge backup, the process will be much faster than using
tar. Dar first reads the catalog (i.e. the contents of the backup),
then it goes directly to the location of the saved file(s) that you
want to
restore and extracts them. When using slices Dar
will ask only for the slice(s) containing the file(s) to restore. (back
to top)
- Archive testing
-
thanks to CRC (cyclic redundancy checks), Dar is able to
detect data corruption in the archive. If data corruption occurs in a
file it will not be possible to restore it but the other files in the
archive can
be restored even when compression is used. (back
to top)
- Archive encryption
-
Dar archives can be encrypted using the Blowfish cypher. (back
to top)
- Isolation
-
The catalog (i.e.: the contents of an archive), can be
extracted (this operation is called isolation) to a much smaller file. This
catalog can in turn be used as reference for making a differential
archive. This means that there is no need to be able to examine an original archive to be able to
create a differential backup from it. Only its catalog is necessary. (back
to top)
- Restore individual files
-
You can restore any combination of individual files and
directories by selecting them in the tree-view display. DarGUI's
selection tools make it possible to select all files with a particular
suffix or with a particular pattern in their name. For example all
files in an archive ending in
.html can be easily selected for restoration. (back
to top)
- Flat restoration
-
It is possible to restore any file without restoring the
directory tree that it was in at the time of the backup. If
this option is enabled, all files will be restored in the root
directory whatever their original location was. (back
to top)
- Pause between slices
-
Dar can be instructed to pause once a slice has
been written. This feature can be used to enable writing to CD between
slices, for
example. (back
to top)
- Timestamp archive names
-
DarGUI can automatically include the date and time of
creation in the name of a DAR archive. (back
to top)
- Scheduled backups
-
DarGUI can schedule a backup script to be run at a specified time once only or regularly. (back
to top)
- Write backup scripts
-
DarGUI can produce Dar backup scripts which can be used independently of DarGUI. (back
to top)
- Track file versions
-
DarGUI can maintain a database of files held in archives, to make it easier to locate a specific version of a file. (back
to top)