First introduced with Windows 2000, a dynamic disk is a hard disk capable of creating volumes (or drives) that span several hard disks. Users of this proprietary disk format, developed by Microsoft with VERITAS (later acquired by Symantec), can create and delete it within an operating system without rebooting.
A dynamic disk allows users to create volumes such as striped and spanned volumes that span multiple disks. It can also hold RAID-5 volumes, mirrored volumes and simple volumes. Dynamic storage uses a database to keep track of information on dynamic volumes on a disk and other dynamic disks in a computer, offering greater flexibility for volume management.
Dynamic disks are only recognizable under a few operating systems, such as Windows 2000 and later (excluding Windows XP Home Edition, Windows Vista Home Basic and Premium versions), Linux kernel version 2.4.8 and later or FreeBSD.
Basic disks are easily upgradeable to dynamic disks. However, once upgraded, downgrading the disk back to its basic form is not so simple. To perform a downgrade, the data on the dynamic disk has to be backed up first. The dynamic storage should then be reformatted as a basic disk. Data is transferred from the backup to the newly reformatted basic disk.