For supported file systems, a disk or volume backup stores only those sectors that contain data. This reduces the resulting backup size and speeds up the backup and recovery operations.

Windows

The swap file (pagefile.sys) and the file that keeps the RAM content when the machine goes into hibernation (hiberfil.sys) are not backed up. After recovery, the files will be re-created in the appropriate place with the zero size.

A volume backup stores all other files and folders of the selected volume independent of their attributes (including hidden and system files), the boot record, the file allocation table (FAT) if it exists, the root and the zero track of the hard disk with the master boot record (MBR). The boot code of GPT volumes is not backed up.

A disk backup stores all volumes of the selected disk (including hidden volumes such as the vendor's maintenance partitions) and the zero track with the master boot record.

Linux

A volume backup stores all files and folders of the selected volume independent of their attributes, a boot record and the file system super block.

A disk backup stores all disk volumes as well as the zero track with the master boot record.

Volumes with unsupported file systems will be backed up sector-by-sector.

Windows operating systems prior to Windows 7 and Windows Server 2008 R2 keep system files and the loader on the same volume, unless a different volume has been specified during the system installation. If Windows files and the loader are on the same volume, selecting either [SYSTEM] or [BOOT] is enough to back up the entire operating system. Otherwise select both [SYSTEM] and [BOOT].

Operating systems starting from Windows 7 and Windows Server 2008 R2 create a dedicated system volume called System Reserved. If you select [SYSTEM], only this dedicated volume will be backed up. Always select both [SYSTEM] and [BOOT] when backing up machines running these operating systems.

Since backup policies are commonly applied to multiple machines with various operating systems, Acronis recommends that you always select both the system and the boot volumes for backup, to ensure the integrity of every operating system.

You can include both Windows and Linux volumes (partitions) in one centralized backup policy.

For instance, it is possible to set up a policy to back up volume C: on Windows machines and partition /dev/hda1 on Linux machines.

Unlike Windows, there is no clear distinction between a volume (partition) and a folder (directory) in Linux. Linux has the root partition (denoted as /), to which elements of various types—including hard disks, directories, and system devices—are attached (mounted), forming a tree similar to the file and folder structure in Windows.

For example, let a Linux machine contain a hard disk which is split into three volumes, or partitions: the first, second, and third partitions. These partitions are available in the tree as /dev/hda1, /dev/hda2, and /dev/hda3, respectively. To perform a disk backup of the, say, third partition, one can type /dev/hda3 in the row of the Volumes to back up selection rules dialog box.

Furthermore, a Linux partition can be mounted anywhere inside the tree. Say, /dev/hda3, can be mounted as a “subdirectory” inside the tree, such as /home/usr/docs. In this case, one can type either /dev/hda3 or /home/usr/docs in the Volume field to perform a disk backup of the third partition.

In general, when setting up a centralized policy to perform volume backups of Linux machines, make sure that the paths entered in the Volume field correspond to partitions (such as /dev/hda2 or /home/usr/docs in the previous example), and not to directories.

Standard names for Linux partitions

Names such as /dev/hda1 reflect the standard way of naming IDE hard disk partitions in Linux. The prefix hd signifies the disk type (IDE); a means that this is the first IDE hard disk on the system, and 1 denotes the first partition on the disk.

In general, the standard name for a Linux partition consists of three components:

• Disk type; hd for IDE drives, sd for SCSI drives, md for software RAID drives (for example, dynamic volumes);
• Disk number; a for the first disk, b for the second disk, etc.;
• Partition number on the disk; 1 for the first partition, 2 for the second partition, etc.

To guarantee backing up selected disks regardless of their type, consider including three entries in the Volumes to back up selection rules dialog box, one for each possible type. For example, to back up the first hard disk of each Linux machine under a centralized policy, you may want to type the following lines in the Volume field:

/dev/hda1

/dev/sda1

/dev/mda1

Names for logical volumes

To back up logical volumes, also known as LVM volumes, specify their full names in the selection rules. The full name of a logical volume includes the volume group to which the volume belongs.

For example, to back up two logical volumes, lv_root and lv_bin, both of which belong to the volume group vg_mymachine, specify the following selection rules:

/dev/vg_mymachine/lv_root
/dev/vg_mymachine/lv_bin

To see the list of logical volumes on a machine, run the lvdisplay utility. In our example, the output would be similar to the following:

--- Logical volume ---
LV Name          /dev/vg_mymachine/lv_root
VG Name          vg_mymachine
…

--- Logical volume ---
LV Name          /dev/vg_mymachine/lv_bin
VG Name          vg_mymachine
…

Tip: To be able to automatically create the volume structure information during recovery, make sure that the volume with the /etc/Acronis directory of each machine is selected for backup. For more details, see “Saving the volume structure information”.