General information and proprietary Acronis technologies
12
Copyright © Acronis, Inc., 2000-2007
Chapter 3.
General information and
proprietary Acronis technologies
3.1
The difference between file archives and disk/partition images
A backup archive is a file or a group of files (also called in this Guide “backups”), that
contains a copy of selected files/folders data or a copy of all information stored on selected
disks/partitions.
When you back up files and folders, only the data, along with the folder tree, is compressed
and stored.
Backing up disks and partitions is performed in a different way: Acronis True Image Server
for Linux stores a sector-by-sector snapshot of the disk, which includes the operating
system, drivers, software applications and data files. This procedure is called “creating a disk
image,” and the resulting backup archive is often called a disk/partition image.
Acronis True Image Server for Linux stores only those hard disk sectors that contain data (for
supported file systems). This reduces image size and speeds up image creation and restoration from
an image.
A partition image contains all its files and folders independently of their attributes (including system
files), a boot record and file system super block.
A disk image includes images of all disk partitions as well as the zero track with master boot record
(MBR).
By default, files in all Acronis True Image Server for Linux archives have a “.tib” extension.
It is important to note, that you can restore files and folders not only from file archives, but
from disk/partition images, too. To do so, mount the image (see
9.1 Mounting an image or
11.3 Restoring files with trueimagemnt), or start the image restoration and select
Restore
specified files or folders
.
3.2 Full,
incremental
and differential backups
Acronis True Image Server for Linux can create full, incremental and differential backups.
A full backup contains all data at the moment of backup creation. It forms a base for further
incremental or differential backup or is used as a standalone archive. A full backup has the
shortest restore time as compared to incremental or differential ones.
An incremental backup file only contains data changed since the last full or incremental
backup creation. Therefore, it is smaller and takes less time to create. But as it doesn’t
contain all data, all the previous incremental backups and the initial full backup are required
for restoration.
Unlike incremental backup, when every backup procedure creates the next file in a “chain,”
a differential backup creates an independent file, containing all changes against the initial