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, are
compressed and stored.
Backing up disks and partitions is performed in a different way: Acronis True Image
Enterprise Server stores a sector-by-sector snapshot of the disk, which includes the
operating system, registry, drivers, software applications and data files, as well as system
areas hidden from the user. This procedure is called “creating a disk image,” and the
resulting backup archive is often called a disk/partition image.
Acronis True Image Enterprise Server stores only those hard disk parts that contain data (for
supported file systems). Further, it does not back up swap file information (pagefile.sys) and
hiberfil.sys (a file that keeps RAM contents when the computer goes into hibernation). This
reduces image size and speeds up image creation and restoration.
A partition image includes all files and folders independent of their attributes (including
hidden and system files), boot record, FAT (file allocation table) and root.
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 Enterprise Server 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 as a virtual disk (see
Chapter 12.
Mounting an image as a virtual drive
) or start the image restoration and select Restore
specified files or folders.
3.2 Full, incremental and differential backups
Acronis True Image Enterprise Server 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
full archive. Generally, a differential backup will be restored faster than an incremental one,
as it does not have to process through a long chain of previous backups.
A standalone full backup may be an optimal solution if you often roll back the system to the
initial state (like in a gaming club or Internet café, to undo changes, made by the guests). In
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