24 Copyright © Acronis, Inc., 2000-2009
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 Echo
Enterprise Server saves a sector-based 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 Echo 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), root and the zero track
of the hard disk with master boot record (MBR).
A disk image includes images of all disk partitions as well as the zero track with the
master boot record (MBR).
All Acronis True Image Echo Enterprise Server archives files have a “.tib” extension by
default.
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
11.2.2 Mounting an image
) or start the image restoration and select
Restore specified
files or folders
.
3.2 Full, incremental and differential backups
Acronis True Image Echo 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
only contains data changed since the last full or incremental
backup creation. Therefore, it is smaller and takes less time to create. However, since it
does not contain all data needed to restore an image,
all
the previous incremental
backups
and
the initial full backup are required for restoration.
A
differential backup
creates an independent file containing all changes since the last
full archive. Generally, data from a differential backup will be restored faster than an
incremental backup, as it does not have to process through a long chain of previous
backups.
