Acronis Backup for PC - User Guide - Manual (Page 237)

237 Copyright © Acronis International GmbH, 2002-2014
Disk backup (Image)
A backup (p. 232) that contains a sector-based copy of a disk or a volume in a packaged form.
Normally, only sectors that contain data are copied. Acronis Backup provides an option to take a raw
image, that is, copy all the disk sectors, which enables imaging of unsupported file systems.
Disk group
A number of dynamic disks (p. 237) that store the common configuration data in their LDM
databases and therefore can be managed as a whole. Normally, all dynamic disks created within the
same machine (p. 240) are members of the same disk group.
As soon as the first dynamic disk is created by the LDM or another disk management tool, the disk
group name can be found in the registry key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\dmio\Boot Info\Primary Disk
Group\Name.
The next created or imported disks are added to the same disk group. The group exists until at least
one of its members exists. Once the last dynamic disk is disconnected or converted to basic, the
group is discontinued, though its name is kept in the above registry key. In case a dynamic disk is
created or connected again, a disk group with an incremental name is created.
When moved to another machine, a disk group is considered as ‘foreign’ and cannot be used until
imported into the existing disk group. The import updates the configuration data on both the local
and the foreign disks so that they form a single entity. A foreign group is imported as is (will have the
original name) if no disk group exists on the machine.
For more information about disk groups please refer to the following Microsoft knowledge base
article:
222189 Description of Disk Groups in Windows Disk Management
http://support.microsoft.com/kb/222189/EN-US/
Dynamic disk
A hard disk managed by Logical Disk Manager (LDM) that is available in Windows starting with
Windows 2000. LDM helps flexibly allocate volumes on a storage device for better fault tolerance,
better performance or larger volume size.
A dynamic disk can use either the master boot record (MBR) or GUID partition table (GPT) partition
style. In addition to MBR or GPT, each dynamic disk has a hidden database where the LDM stores the
dynamic volumes' configuration. Each dynamic disk holds the complete information about all
dynamic volumes existing in the disk group which makes for better storage reliability. The database
occupies the last 1MB of an MBR disk. On a GPT disk, Windows creates the dedicated LDM Metadata
partition, taking space from the Microsoft Reserved Partition (MSR.)
Disk 1
MBR LDM
database
1 MB
Disk 2
Protec-t
ive
MBR
GPT
Microsoft
Reserved
Partition (MSR)
LDM
database
GPT