Managing Windows Server 2012 Storage and File Systems : Storage Management (part 12) - Managing volumes on dynamic disks - Creating a simple or spanned volume, Configuring RAID 0

You create simple and spanned volumes in much the same way. The differences between these volume types are subtle:

If you later need more space, you can extend a simple or spanned volume type by using Disk Management. Here, you select an area of free space on any available disk and add it to the volume. When you extend a simple volume onto other disks, it becomes a spanned volume. Any volume that you want to extend should be formatted using NTFS because only NTFS volumes can be extended.

Simple and spanned volumes aren’t fault tolerant. If you create a volume that spans disks and one of those disks fails, you won’t be able to access the volume. Any data on the volume will be lost. You must restore the data from backup after you replace the failed drive and re-create the volume.

To create a simple or spanned volume, complete the following steps:

RAID level 0 is disk striping. With disk striping, two or more volumes—each on a separate drive—are configured as a striped set. Unlike spanning, Windows breaks the data to be written into blocks called stripes and then writes the stripes sequentially to all disks in the set. So, if there are three disks in the set, Windows writes part of the data to the first disk, part of the data to the second disk, and part of the data to the third disk—this process of alternating between the disks is called striping.

Although the boot and system volumes shouldn’t be part of a striped set, you can place volumes for a striped set on up to 32 drives, but in most circumstances sets with 2 to 5 volumes offer the best performance improvements. When 3 to 32 drives are used, the major advantage of disk striping is speed. Data can be accessed on multiple disks using multiple drive heads, which improves performance considerably. When you try to use more than 32 drives, the performance improvement decreases significantly.

When you create striped sets, you’ll want to use volumes that are approximately the same size. Disk Management bases the overall size of the striped set on the smallest volume size. Specifically, the maximum size of the striped set is a multiple of the smallest volume size. For example, if the smallest volume is 100 GBs, the maximum size for a three-disk striped set is 300 GBs.

You can maximize performance using disks that are on separate disk controllers. This allows the system to simultaneously access the drives. Keep in mind that this configuration offers no fault tolerance. If any hard disk drive in the striped set fails, the striped set can no longer be used, which essentially means that all data in the striped set is lost. You’ll need to re-create the striped set and restore the data from backups. 

You can create a striped set by following these steps:

After you create a striped volume, you can use the volume just like any other volume. You can’t extend a striped set after it’s created. Therefore, you should carefully consider the setup before you implement it.

Simple disks are the easiest to troubleshoot and recover because there is only one disk involved. Spanned or striped disks, on the other hand, have multiple disks and the failure of any one disk makes the entire volume unusable. The drive status might show as Missing, Failed, Online (Errors), Offline, or Unreadable.

The Missing (and sometimes Offline) status usually happens if drives have been disconnected or powered off. If the drives are part of an external storage device, check the storage device to ensure that it is connected properly and has power. Reconnecting the storage device or turning on the power should make it so that the drives can be accessed. You then must start Disk Management and rescan the disks by selecting Rescan Disks from the Action menu. When Disk Management finishes, press and hold or right-click the drive that was missing, and then choose Reactivate.

The Failed, Online (Errors), and Unreadable statuses indicate input/output (I/O) problems with the drive. As before, try rescanning the drive, and then try to reactivate the drive. If the drive doesn’t come back to the Healthy state, you might need to replace it.

One of the advantages that dynamic disks have over basic disks is that you can easily move them from one computer to another. For example, if after setting up a server, you decide that you don’t really need its two additional hard disk drives, you could move them to another server where they could be better used. Before you move disks, you should access Disk Management on the server where the dynamic disks are currently installed and check their status. The status should be Healthy. If it isn’t, you should fix any problems before moving the disks.

Next check to see whether any dynamic disks that you want to move are part of a spanned, extended, mirrored, striped, or RAID-5 set. If they are, you should make a note of which disks are part of which set and plan on moving all disks in a set together. If you are moving only part of a disk set, you should be aware of the consequences. For spanned, extended, or striped volumes, moving only part of the set will make the related volumes unusable on the current computer and on the computer to which you are planning to move the disks. If you plan to move only one disk of a mirrored volume, you should break the mirror before you move it. This ensures that you can keep using the disks on both computers. For RAID-5 volumes, you should move all of the disks in the set if possible. If you move only part of the RAID-5 set, you might find that you can’t use the set on either computer.

To move the disks, open Computer Management and then, in the left pane, select Device Manager. In the Device List, expand Disk Drives. This shows a list of all the physical disk drives on the computer. Press and hold or right-click each disk that you want to move, and then select Uninstall. If you are unsure which disks to uninstall, press and hold or right-click each disk and select Properties. In the Properties dialog box, click the Volumes tab and then choose Populate. This shows you the volumes on the selected disk. In Computer Management, select Disk Management. Press and hold or right-click each disk that you want to move, and then select Remove Disk.

After you perform these procedures, you can move the dynamic disks. If the disks are hot swappable and this feature is supported on both computers, remove the disks from the original computer and then install them on the destination computer. Otherwise, turn off both computers, remove the drives from the original computer, and then install them on the destination computer. When you’re finished, restart the computers. On the destination computer, access Disk Management, and then select Rescan Disks on the Action menu. When Disk Management finishes scanning the disks, press and hold or right-click any disk marked Foreign and tap or click Import. You should now be able to access the disks and their volumes on the destination computer.