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Understanding Disk Volume Types

Tuesday, 28 January 2014

A dynamic disk can contain an unlimited number of volumes that function much like primary partitions on a basic disk, but you cannot mark an existing dynamic disk as active. When you create a volume on a dynamic disk using the Disk Management snap-in in Windows Server 2012, you choose from the following five volume types:
Simple Volume:
 Simple volume Consists of space from a single disk. After you have created a simple volume, you can extend it to multiple disks to create a spanned or striped volume, as long as it is not a system volume or boot volume. You can also extend a simple volume into any adjacent unallocated space on the same disk or, with some limitations, shrink the volume by deallocating any unused space in the volume.
Spanned Volume:
 Spanned volume Consists of space from 2 to 32 physical disks, all of which must be dynamic disks. A spanned volume is essentially a method for combining the space from multiple dynamic disks into a single large volume. Windows Server 2012 writes to the spanned volume by filling all of the space on the first disk and then fills each of the additional disks in turn. You can extend a spanned volume at any time by adding
disk space. Creating a spanned volume does not increase the disk’s read/write performance, nor does it provide fault tolerance. In fact, if a single physical disk in the spanned volume fails, all of the data in the entire volume is lost.
Striped Volume:
Striped volume Consists of space from 2 to 32 physical disks, all of which must be dynamic disks. The difference between a striped volume and a spanned volume is that in a striped volume, the system writes data one stripe at a time to each successive disk in the volume. Striping provides improved performance because each disk drive in the array has time to seek the location of its next stripe while the other drives are writing. Striped volumes do not provide fault tolerance, however, and you cannot extend them after creation. If a single physical disk in the striped volume fails, all of the data in the entire volume is lost.
Mirrored Volume:
Mirrored volume Consists of an identical amount of space on two physical disks, both of which must be dynamic disks. The system performs all read and write operations on both disks simultaneously, so they contain duplicate copies of all data stored on the volume. If one of the disks fails, the other continues to provide access to the volume until the failed disk is repaired or replaced.
RAID-5 Volume:
RAID-5 volume Consists of space on three or more physical disks, all of which must be dynamic. The system stripes data and parity information across all of the disks so that if one physical disk fails, the missing data can be re-created using the parity information on the other disks. RAID-5 volumes provide improved read performance, because of the disk striping, but write performance suffers, due to the need for parity calculations.