Acronis Backup for Linux Server - User Guide - Manual (Page 104)

104 Copyright © Acronis International GmbH, 2002-2014
Type
A basic MBR disk can contain up to four primary volumes or up to three primary volumes and
multiple logical drives. By default, the program selects the original volume's type. You can change
this setting, if required.

Primary. Information about primary volumes is contained in the MBR partition table. Most
operating systems can boot only from the primary volume of the first hard disk, but the number
of primary volumes is limited.
If you are going to recover a system volume to a basic MBR disk, select the Active check box.
Active volume is used for loading an operating system. Choosing active for a volume without an
installed operating system could prevent the machine from booting. You cannot set a logical
drive or dynamic volume active.

Logical. Information about logical volumes is located not in the MBR, but in the extended
partition table. The number of logical volumes on a disk is unlimited. A logical volume cannot be
set as active. If you recover a system volume to another hard disk with its own volumes and
operating system, you will most likely need only the data. In this case, you can recover the
volume as logical to access the data only.
File system
By default, the recovered volume will have the same file system as the original volume has. You can
change the volume's file system during recovery, if required.
Acronis Backup can make the following file system conversions: FAT 16 -> FAT 32 and Ext2 -> Ext3.
For volumes with other native file systems, this option is not available.
Assume you are going to recover a volume from an old, low-capacity FAT16 disk to a newer disk.
FAT16 would not be effective and might even be impossible to set on the high-capacity hard disk.
That's because FAT16 supports volumes up to 4 GB, so you will not be able to recover a 4 GB FAT16
volume to a volume that exceeds that limit, without changing the file system. It would make sense
here to change the file system from FAT16 to FAT32.
Older operating systems (MS-DOS, Windows 95 and Windows NT 3.x, 4.x) do not support FAT32 and
will not be operable after you recover a volume and change its file system. These can be normally
recovered on a FAT16 volume only.
Volume (partition) alignment
Acronis Backup automatically eliminates volume misalignment – a situation, when volume clusters
are not aligned with disk sectors. The misalignment occurs when recovering volumes created with
the Cylinder/Head/Sector (CHS) addressing scheme to a hard disk drive (HDD) or solid-state drive
(SSD) drive that has a 4-KB sector size. The CHS addressing scheme is used, for example, in all
Windows operating systems earlier than Windows Vista.
If volumes are misaligned, the cluster overlaps more physical sectors than it would have occupied if
aligned. As a result, more physical sectors need to be erased and rewritten each time the data
changes. The redundant read/write operations noticeably slow down the disk speed and overall
system performance. SSD drive misalignment decreases not only system performance, but drive
lifetime. Since SSD memory cells are designed for a certain amount of read/write operations,
redundant read/write operations lead to early degradation of the SSD drive.
When recovering dynamic volumes and logical volumes created in Linux with Logical Volume
Manager (LVM), the appropriate alignment is set up automatically.