12 Copyright © Acronis International GmbH, 2002-2015
Converting a dynamic disk to basic may require deleting some volumes on it, such as volumes that
occupy more than one disk.
3.2 Types of basic volumes
A basic disk can store two types of volumes: primary volumes and logical volumes.
The main difference between a primary volume and a logical volume is that a primary volume can be
used as the system or active volume—that is, a volume from which the machine or its Windows
operating systems start.
On each basic GPT (p. 73) disk, you can create up to 128 primary volumes. The maximum volume size
on a GPT disk is 16 exabytes.
Unlike basic GPT disks, on each basic MBR (p. 75) disk, you can create either up to four primary
volumes, or up to three primary volumes plus an unlimited number of logical volumes. The maximum
volume size on an MBR disk is 2 terabytes.
If you are not planning to use more than four volumes on the disk, all volumes can be primary
volumes. Otherwise, you can leave the active volume and the system volume as primary volumes,
and then create as many logical volumes as required.
If the disk already has four primary volumes and you need to create a fifth volume, first convert one
of the volumes—but not the system or active volume—to a logical volume, as described in
Converting a primary volume to logical (p. 35), and then create a new logical volume.
3.3 Types of dynamic volumes
The following are the types of dynamic volumes that are supported by Acronis Disk
Director—provided that they are supported by the operating system, as shown in Dynamic volume
types support (p. 14).
Simple volume
A volume (p. 79) that consists of disk space from a single dynamic disk (p. 71).
Physically, a simple volume can occupy more than one region of disk space, which can be logically
perceived as a single contiguous region.
When you extend a simple volume to another disk, the volume becomes a spanned volume (p. 77).
When you add a mirror to a simple volume, the volume becomes a mirrored volume (p. 75).
Spanned volume
A volume that consists of disk space from two or more dynamic disks (p. 71), in portions that do not
need to be equally-sized.
A spanned volume can reside on up to 32 disks.
Unlike mirrored (p. 75) and RAID-5 volumes, spanned volumes are not fault-tolerant. Unlike striped
volumes (p. 77), spanned volumes do not provide faster data access.
Striped volume
A volume that resides on two or more dynamic disks and whose data is evenly distributed across
equally-sized portions of disk space (called stripes) on those disks.
