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I have a 2 TB disk in my PC right now (100 GB is for partition C: and the rest (~1.78 TB is for partition D:, which is nearly full. I have another spare 2 TB disk which I would like to use.

Due to the fact everything is mapped to my D: partition (it's my data disk) I wish to expand that without using it as a raid array. So, simply adding my other 2 TB disk and expanding the current D: partition to roughly 4 TB.

I have two questions regarding this:

  • Is this even possible?
  • If yes, what would happen if one of the disks dies? Will I lose all my data on both disks (even though it's not raid) or will simply some files not be recoverable and some are (since they reside on the other disk)?
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I think Windows 8 will have that feature, not that it helps you now. – Moab Jun 12 '12 at 14:02
Since you don't want to use RAID you will have to purchase a 4TB drive and duplicate the current data on your hdd to it. What you want to do is not possible with RAID. The Windows 8 feature that Moab is a solution but is not really designed for internal storage. – Ramhound Jun 12 '12 at 14:16
up vote 2 down vote accepted

You need to make a spanned volume, but first you have to change them to dynamic disks instead of basic disks:

  1. Open the Disk Management console (diskmgmt.msc)
  2. Right-click each of the disks in question and select Convert to Dynamic Disk
  3. Create a new volume using the free space from the two disks

Creating a spanned volume is a it's a little involved; this video helps, but some third-party partitioning tools (such as MiniTool PartitionWizard) can simplify the process.

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Thanks for the answer. However I will not be using it, since all the data is lost then. I'll just use a separate volume (E:) then ;-) – Devator Jun 13 '12 at 6:58
Strange, it should not erase anything. Converting a basic disk to dynamic should be non-destructive (going back is destructive), and creating a spanned volume should be likewise non-destructive since all it does is to create a virtual volume and assign the free space from the existing dynamic disks to it. Where did you see a warning about losing the data? – Synetech Jun 13 '12 at 17:09
Sorry, I actually meant that if one of the disks dies, then all data is lost. – Devator Jun 13 '12 at 17:10
Ah, yes. Spanned volumes are not fault-tolerant; if one of the disks go, then the whole volume could be lost (technically, you can still get the data from the other drive(s); it just won't be easy and will require a bit of work and time). Unfortunately if you want fault-tolerance AND spanning, then you have no choice but to go RAID 0+1/1+0. If the hardware support is what you are concerned about, perhaps software RAID would work. You can implement a "virtual RAID" system using software. – Synetech Jun 13 '12 at 17:15

AFAIK it is not possible without RAID, yet. Windows 8 will add a feature called Storage Spaces that will allow you to combine multiple internal and external drives into a single pool of storage. Supersite has a good writeup of all of the features but here are some of the highlights:

  • Data Redundancy - files will be mirrored and if more than two drives are used parity bits are stored
  • Explorer integration - Windows explorer will see the space as one drive
  • Virtual Storage - You can provision more space than the physical drives actually hold and add more later
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Thanks, even though it's no use for me it's an interesting thing to read. – Devator Jun 13 '12 at 6:59

How about creating a junction point? That way the apps still save stuff to D:, but some of the folders are actually located on the spare disk. You can automate it with Steam Mover

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I was thinking also about Symbolic linking / junction points but have to fiddle with it a bit more. – Devator Jun 13 '12 at 6:57

Yes, this is possible.

You could turn the second partition on the first disk and a partition on the second disk into a RAID 1 stripe. You would have a 100GB C: and a 3.56TB D:

But...If either of the drives dies then you loose all data on D:

Another way might be with with 'new spanned volume' via windows diskmanager. I never used that myself, so I will leave the details on that to someone else.

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RAID-1 would turn it into a 1.8TB partition, but it would be safe against a crash of either disk. What you describe (sizes added, data lost if either disk dies) is in fact a spanned volume. – MSalters Jun 12 '12 at 14:11
You ignored the author requirement: "I wish to expand that without using it as a raid array." which means this option isn't a real solution. – Ramhound Jun 12 '12 at 14:15

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