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How much risk is involved in converting a basic disk into a dynamic disk in Windows Server 2003 R1 and R2? I just expanded my vDisk in VMWare but since the disk is basic it will not let me expand the volume in Windows. Is there potential for data loss, OS corruption, etc? Or is this a relatively safe operation?

Edit: This image is backed up nightly.

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Do you receive an error or is it just nothing happening with the volume size? – Mathias R. Jessen Mar 14 '12 at 20:11
@Mathias R. Jessen: The OP is probably trying to extend the boot volume, which isn't permitted in Windows Server 2003 (unless, obviously, you're not booted from that volume). – Evan Anderson Mar 14 '12 at 20:13
The volume you have selected may not be extended. Please select another volume and try again. – tacos_tacos_tacos Mar 14 '12 at 20:14
@MathiasR.Jessen, yes, I am. That is probably why the volume cannot be extended, I'm guessing – tacos_tacos_tacos Mar 14 '12 at 20:16
Are you trying to extend the boot volume? If so you'll have to reboot to do this on Windows Server 2003. – Evan Anderson Mar 14 '12 at 20:17
up vote 6 down vote accepted

Stop! You don't need to convert the disk to a "Dynamic Disk" to expand the volume!

Just boot a Windows 7 or Windows Server 2008 R2 setup ISO on that VM. Once you've booted the setup media open a command-prompt (Shift-F10) and use the DISKPART tool to EXTEND the volume.

From the DISKPART prompt you'd do a list disk to list the disks in the machine, a select disk # (where # is the ordinal for the disk containing the volume you want to extend), a list partition to list the partitions on that disk, and a select partition # (where # is the ordinal for the volume you want to extend). After that, enter the command extend and the partition will be extended to fill the entire free space on the disk.

This is a pretty safe operation (I've never had a problem and I've done it a lot) but, even so, you really should have a backup before you proceed with this operation. Better safe than sorry.

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I tried this before, but I got The volume you have selected may not be extended. Please select another volume and try again. – tacos_tacos_tacos Mar 14 '12 at 20:14
Ah I just read your entire post. This system is a critical one so it cannot go down for a reboot to a setup ISO. – tacos_tacos_tacos Mar 14 '12 at 20:15
If you're talking about the boot volume then you'll have to reboot to convert the disk to a dynamic disk anyway. Personally I prefer to keep disks basic if at all possible because basic disks are more amenable to data recovery and access by third-party operating systems. – Evan Anderson Mar 14 '12 at 20:17
@jshin47 it has to go down some time. If it doesn't, that means that you're not patching your critical systems. – MDMarra Mar 14 '12 at 20:18
@jshin47: I find this to be a quick route if only because I have Windows 7 and Server 2008 R2 ISOs laying around on virtually every ESX(i) datastore I work on. – Evan Anderson Mar 14 '12 at 20:25

Converting a disk from basic to dynamic is totally safe, but it's also completely useless if you don't need the software RAID features of dynamic disks.

You don't need to convert a disk to a dynamic one in order to extend a partition; this can be done on basic disks, too. But not on the system partition, unless you're using Windows Server 2008 or later.

In order to extend the system partition on a Windows Server 2003 system, you need to reboot it into something different from its main O.S. disk. As others have said, a Windows 7 or a Windows Server 2008 R2 DVD will do the trick.

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