Long time readers of this site know that I have been, and continue to be, a fan, supporter, and user of Windows Home Server. And most will recall the controversy that ensued when Microsoft removed one of Home Server's best features, Drive Extender, from Windows Home Server 2011.

Drive Extender, for those unfamiliar, was a brilliant idea, albeit one that was later proven not to have the technical chops to make it into mainstream Windows versions. It provided two key features: The ability to automatically replicate data across two disks, providing redundancy in the event of a hard drive failure, and a unique feature in which storage on multiple disks was accessed a single pool of storage.

As it was stripped from WHS 2011 for technical reasons, technology enthusiasts howled in protest. But I continue using WHS 2011 despite the Drive Extender fiasco, and as I wrote a year ago in I'm Betting On Windows Home Server 2011, the addition of an automated Server Backup feature, while not identical to Drive Extender's automatic data redundancy magic, is acceptable. And it has been, really. I've been using WHS 2011 as my primary data archive for over a year now. All is well.

And yet. Like many WHS users and fans, I pine a bit for Drive Extender still. It was an amazingly useful solution, and one I had always expected to make its way first to Windows Server and then, ultimately, to Windows on the desktop as well.

In Windows 8, that's finally happening. No, the feature isn't called Drive Extender, but for all intents and purposes, this technology, called Storage Spaces, is absolutely the spiritual successor to Drive Extender. And if you've been looking for a way to easily manage the storage in multiple hard drives in a seamless, elegant fashion, Storage Spaces is going to make you very, very happy indeed.

Storage Spaces 101

Storage Spaces, like Drive Extender before it, provides two basic services:

Data redundancy. Storage Spaces utilizes data mirroring technology to ensure that there are at least two copies of data, each of which lives on a different disk, to help prevent data loss in the event of a hard disk failure.

Single pool of storage. You can organize the storage on your various hard disks in one or more storage pools that are managed as a single entity despite having storage that could span many disks. And unlike complex technologies such as RAID, these disks can be of multiple different sizes and types, and can include fixed disks (SATA) and external storage (like USB). You're free to mix and match as you like, and adding storage to a storage pool is as simple as plugging in a new disk and adding it to that pool using a very simple interface.

OK, that sounds an awful lot like Drive Extender, I know. But aside from being implemented differently under the covers, Storage Spaces also includes a number of features that weren't present in Drive Extender. These include: 

Explorer integration. Where Drive Extender was about abstracting storage from Explorer, Storage Spaces integrates with Explorer, much like libraries do. So you get a virtual view of the space from Explorer, and with a normal, widely understood drive letter. This is useful for users, but also for applications that expect such things. So compatibility is excellent.

More data redundancy options. Where Drive Extender automatically ensured that data could live on two hard drives, Storage Spaces works with two or more hard drives. That means you could configure this feature to storage data on three different physical disks if you wanted. (Spaces also supports a parity feature which provides you with two different copies of your data but requires three physical disks; the third disk is used for parity purposes.)

Virtual storage. Storage Spaces lets you create a space that is bigger than the total amount of physical storage. This feature, which is called thin provisioning, lets you pre-configure a space to a large size and then add physical storage later, when it's actually needed. (You'll be prompted when needed through Action Center.)

ReFS compatibility. On Windows Server 8, you can optionally mix and match NTFS and Resilient File System (ReFS)-based disks. ReFS is a new file system aimed at very large disks that will only be available on Windows Server for the time being. But Microsoft will be porting it to the Windows client in the future as well.

As is always the case with new technology, Storage Spaces brings with it some new terminology.  Where a storage pool can consist of two or more disks, you access this storage via a new entity called a space. To understand what this means, consider how libraries work in Windows 7 and 8. In these OSes, you may have physical folders such as My Pictures and Public Pictures, and the combined, virtual view of these folders is called the Pictures library. Well, spaces work the same way. You may combine your E: and F: drives into a single pool of storage. But you will access that pool through the file system using a virtual view called a space. In this case, it could be called the Pictures space.

Real life Storage Spaces

OK, enough theory. To see how Storage Spaces really works in Windows 8, it's best to just connect a couple of hard drives and see what happens. So I connected two 3 TB USB 3.0-based hard drives to my main Windows 8 desktop. And this works as expected: Both disks show up in Windows Explorer normally.

To use them with Storage Spaces, you must access the Storage Spaces control panel. Since this is a desktop-type control panel, there are a number of ways to do this, but I tend to go with Start screen search: Just hit WINKEY and then type storage spaces. You'll find it under Settings.

Here's the Storage Spaces control panel.

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To get started, I clicked Create a new pool and storage space. Storage Spaces will show you the available disks (essentially all attached storage aside from the boot and system partitions) along with a warning that adding formatted disks to a pool will result in them being formatted. That is, you will lose data, and it cannot be recovered.

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Being careful not to select my normal data drive, I selected the two 3TB disks and clicked Create pool.

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The wizard creates the pool and then provides a number of important options to configure. These include the name of the space, the drive letter it will use, the type of resiliency (none, two-way mirror, three-way mirror, or parity), and the logical size of the space (the initial size of which will be based on the resiliency type you choose). Remember that the logical size of the space can actually be bigger than the physical size of the disks if you want to use thin provisioning.)

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Since I was working with two physical disks, I chose "two-way mirror" as the parity type. This means that the logical size of the space was 2.72 TB (i.e. ~3TB), since I would be replicating data across the two physical disks. I did not increase the logical size of the space, which I named Data Space and assigned to drive letter S:.

I then clicked Create storage space.  The wizard formatted the space and, after a few moments, opened an Explorer window displaying this new space which, as expected, appears as a normal drive letter. Here's the view from Computer:

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In fact, it's almost too normal: There's no physical indication that this "drive" is anything special. To the underlying system, Metro-style apps, Windows applications, and to the user, this storage space is for all intents and purposes just another normal drive.

That is, of course, the point. Right-click the drive and look at the properties and you think you're looking at a single, physical hard drive. You can add this location, or any folders it will contain, to libraries, just as you do with a normal disk. You can backup to it, or back it up elsewhere, and it just works. You can store files, install applications, do all the things you'd do with any drive. You can even protect it with BitLocker.

Under the covers, of course, it's far more powerful than a single drive. Anything stored within is being replicated across the two physical disks, automatically. You could add more spaces to the pool, rename the pool or its contained spaces, and perform other management tasks. In fact, if you return to the Storage Spaces control panel, you'll see a number of details about the pool and space you've created.

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And with the Physical Drives pane open...

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Storage Spaces and the future

Storage Spaces work so well, and in such a familiar fashion, that Windows Home Server fans will no doubt be wondering how this impacts the future of their favorite product. There are two possibilities, I suppose.

In the first, Storage Spaces will of course be part of some future WHS version that is based on Windows Server 8. This WHS version would presumably offer the other advantages of WHS too, including multi-PC backup and recovery, remote access, and more.

In the second scenario, Microsoft doesn't release another WHS version and enthusiasts are forced to turn to Windows Small Business Server Essentials 8 or, more likely, to using a Windows 8-based PC with Storage Spaces to handle their data storage and multimedia-sharing needs. Such a solution would not include the multi-PC backup we've long loved, but would at least offer remote access to PC data through HomeGroup and network-based sharing (on the local network) and to PC-based files through the coming SkyDrive Remote Fetch feature. 

Obviously, each case has its pros and cons, and equally obviously, WHS is sort of a tough sell these days, so the second scenario is perhaps the more likely. But either way, our future will include Storage Spaces. So this is a technology that users of all kinds will want to know about, and combined with cloud-based backup, it will protect your valuable data, no matter how much storage you require.

Note: There's a lot more to discuss around Storage Spaces, so I'll provide a second part to this article in the future.