Windows Small Business Server 2011 : Partitions and Volumes (part 2) - Extending or Shrinking a Volume

12/11/2012 10:31:20 AM

2. Extending or Shrinking a Volume

Windows Small Business Server 2011 has the ability to extend or shrink a volume, on the fly, without shutting down the server or rebooting. When you shrink a volume, you create unallocated space on the volume. That unallocated space can then be used to extend another volume.

2.1. Shrinking a Volume

The ability to shrink a volume is a new feature added to Windows Server 2008, giving you greater flexibility in managing your disks. Before Windows Server 2008, you had to use a third-party application to shrink a volume. And even now third-party applications such as Acronis Disk Director give you greater flexibility and control over resizing partitions and volumes than Disk Management. With Disk Management, you can shrink down the unused space on a volume, recovering some of that empty space to use on other volumes, but the most you can expect to recover is about 50 percent of the free space on the volume. If the file system on the volume is fragmented, you might not get even that much.

To shrink a volume, follow these steps:

Open the Disk Management console if it isn’t already open.
Select the volume you want to shrink and right-click to open the menu shown in Figure 11.

Figure 11. The Action menu for simple volume
Select Shrink Volume from the menu to open the Shrink dialog box shown in Figure 12.

Figure 12. The Shrink dialog box for the simple volume D
Select the amount to shrink the volume and then click Shrink to change the size of the volume.

2.2. Extending a Volume

You can add space to a volume without having to back up, reboot, and restore your files if it is a simple volume or a spanned volume. You do this by converting the volume to a spanned or extended volume that incorporates unallocated space on any disk. Unfortunately, you can’t increase the size of a mirrored, striped, or RAID-5 volume simply by adding disks to the array.

Note:

Some hardware RAID controllers support dynamically expanding RAID volumes. When combined with hot-add disks, this gives you a far more flexible solution for managing your internal storage. But even after you’ve extended a hardware RAID volume, you’ll still need to extend it using Diskmanager or Diskpart.

To extend a volume, complete the following steps:

In the Disk Management console, right-click the volume you want to extend. Choose Extend Volume to open the Extend Volume Wizard.
Click Next to open the Select Disks page, select one or more disks from the list of disks that are available and have unallocated space. Click Add to add the selected disk or disks, and indicate the amount of space you want to add, as shown in Figure 13.

Figure 13. The Select Disks page of the Extend Volume Wizard
Click Next and the Extend Volume Wizard displays a final confirmation page before extending the volume. Click Finish to extend the volume. The extended volume is shown in Figure 14.

Figure 14. The Disk Management console, showing the new extended volume D

Warning:

IMPORTANT A spanned (extended) volume is actually less reliable than a simple disk. Unlike a mirror or RAID-5 volume, which has built-in redundancy, a spanned or striped volume will be broken and all its data lost if any disk in the volume fails.

REAL WORLD: Extending—Friend or Foe?

Most people responsible for supporting a busy server have wished at some point that they could simply increase the space of a particular volume or drive on the fly when it got low on space—preferably without having to bring the system offline for several hours while the entire volume is backed up and reformatted to add the additional hard disks, the backup is restored, and the share points are re-created. Fun? Hardly. Risky? Certainly. And definitely a job that means coming in on the weekend or staying late at night—in other words, something to be avoided if at all possible.

All this makes SBS’s ability to create additional space on a volume without the need to back up the volume, reformat the disks, and re-create the volume a seductive feature. However, unless you’re running hardware RAID, you should think twice before jumping in. Only simple or spanned volumes allow you to add storage on the fly, and because neither is redundant, using them exposes your users to the risks of a failed drive. Yes, you have a backup, but even under the best of circumstances, you’ll lose some data if you need to restore a backup. Further, using spanned volumes actually increases your risk of a hard disk failure. If any disk used as part of the spanned volume fails, the entire volume is toast and will need to be restored from backup.

Why, then, would anyone use spanning? Because they have hardware RAID to provide the redundancy. This combination offers the best of both worlds—redundancy provided by the hardware RAID controller and flexibility to expand volumes as needed, using Disk Management. Yet another compelling argument for hardware RAID, as if you needed any more.

Note:

Windows Small Business Server 2011 uses the terms extended and spanned nearly interchangeably when describing volumes. Technically, however, a spanned volume must include more than one physical disk, whereas an extended volume can also refer to a volume that has had additional space added to the original simple volume on the same disk.