[How-To] Creating spanned volumes


Staff member
How to create a spanned volume in Windows XP
by electron

A spanned volume allows you to combine several hard drives/partitions to create a new single 'volume'. Why would you want to do this? I personally needed this for my home built DVR/HTPC. I have a 60GB drive and an 80GB drive, but my OS only requires around 10 gigs. Since most dvr software packages don't support storing the video files to multiple drives, I would have to either choose the 80GB drive, or the remaining 50GB on my first drive. As recording in mpeg2 can take up several gigabytes per hour, depending on the quality settings, you really want to grab every gigabyte you can.

With spanning, you can combine the 50GB on the first drive with the 80GB on the second drive, and have one single 150GB drive. You are also able to increase the size of the spanned volume by extending it onto additional dynamic disks. Windows supports 5 types of dynamic volumes: simple, spanned, striped, mirrored and Raid-5. In order to get the most space out of our hard drives, we will use spanned. You can extend a spanned volume onto a maximum of 32 dynamic disks.
Why not?
Spanning is only supported on dynamic disks, this how-to will show you how to upgrade a basic disk to a dynamic disk, but dynamic disks are harder to recover in case of hard drive failure (but not impossible). Spanned volumes are not fault tolerant and cannot be mirrored and should not be used for mission critical data such as the OS or files you plan on storing long term! If one drive fails, the entire span will be broken!
In this example, I am using a 60GB drive and a 80GB drive, I will be spanning the remaining 46.13GB from the first drive and the 80GB from the unused second drive (74.53GB is the true available space in this example).
1) Upgrade basic disk to dynamic volume
One of the requirements to use this feature is upgrading your hard drives from basic to dynamic.

Close any applications you might have running as it will require a reboot after this process. Right click on 'My Computer' and select 'Manage' as shown in the screenshot above. Once you are there, go to 'Disk Management' (see second screenshot) and you will see the layout of your current storage devices. Proceed by right clicking on 'Disk 1' and select 'Convert to Dynamic Disk' as shown in the screenshot below.

You will be prompted with a dialog box allowing you to select the disks you wish to upgrade, select both hard drives:


After selecting the disks, you will get the following prompt, take a look at it and proceed by clicking 'Convert':


Once you click 'Convert', it will ask you to confirm this operation (you will not lose any data):


After converting the disks, a reboot is required, do not try to get around this!

2) Create the spanned volume

Now that we have upgraded our disks and rebooted our system, go back into disk management as shown in step 1, right click on the first block of unallocated space, and the 'New Volume Wizard' will appear and guide you through this process, as shown in the screenshots below

Click Next which will bring to you to the following screen where you can select the type of spanned volume. Remember, we are trying to create a spanned volume, so select this option and click next:

Add both disks to the selection as shown in the screenshots below:

Assign a drive letter (or mount it as a folder if you wish), click next and perform a format as shown in the screenshots below:

Congratulations, you have now successfully created a spanned volume! You can see the results in Disk Management, it should show a spanned volume (it uses the purple color to indicate these 2 drives are part of 1 spanned volume), and in the overview, it should show the new volume and the space you now have available (in this example it is 120.66GB).

I'd be careful doing this. I'm pretty sure this wasn't supposed to be a "feature" of 2000 or XP and I'd be concerned with MS "fixing" it in one of their updates.

If they did you'd probably end up losing all the data on the spanned volume and that would really suck.
It's a well documented and used feature, it's even in the help file, and I have been using it for a very long time, it's not just a feature, it's part of the file system, they can't just disable it.
no problem, if you do find such statements, please let me know so I can include this, we are only looking out for each other ;)
ok, I did a little hunting because I could've sworn I had read that wasn't a feature that is supposed to be included.

Turns out I'm half right. There's a registery hack to enable raid-1/raid-5 in Windows 2000/XP that isn't supposed to be there.

And of course, here's the linkage on how to do it: Zoink!
yes, Mirroring/Raid5 has been removed from XP (however, it's mentioned in the XP help file for some reason, it's there in win2k tho), but spanning is supported without any hacks.
Hi Guys,

I am just new to this site. I was looking through the notes and instructions on how to sapn, and I am having some difficulties.

1> I know you've said "not recommended with OS", but can I span three drives including the one holding the OS?

- I am running three scsi 4.3 gb drives with windows xp pro

- I want to span c:,d:,e: over one install, to total about 12gb

2> I tried everything in the links and instructions, and have come up with the ABILITY to span the drives, but they're all showing up as 7MB sizes.

- I can span these three together, but obviously, I only get 21MB when finished. It shows up as an extension or Partition of each drive in drive management. I did NOT choose to format the drives when running the config tool, because (of course) my OS is stored on one of the drives.

Anyone have any suggestions or "the answer" for what I am trying to do?

Thanks in advance...
I don't think the span can include the OS drive, as spanning uses unallocated disks space, however I was unable to confirm this, so unless someone else knows, there is only one way to find out. If you would lose your OS drive, it would probably warn you anyways. As for the 7MB issue, can you take a screenshot of your disk management profile?