Windows 8's new Storage Spaces functionality will easily allow users and system administrators to pool different physical drives together into one logical drive, writes Rajeev Nagar on the Building Windows 8 blog. This functionality, which is similar in some ways to the now-discontinued Windows Home Server Drive Extender, will allow drives of any capacity connected to a PC by USB, SATA, or SAS interfaces to be seen by the OS as one large drive.

Once you've created a storage pool using two or more drives, you can then set up one or more "spaces" that will be seen by the operating system as a logical drive which can be formatted, partitioned, and used just as a physical disk would be. To provide redundancy, you can either apply the "mirrored" attribute to your pool, which makes sure that a copy of every file in the pool is stored on at least two different physical drives, or the "parity" attribute, which uses some drive space to store redundancy information - in the event of drive failure, this information is used to rebuild your pool and enforce mirroring. Microsoft notes that while the two redundancy options are similar, the "parity" attribute is best used for large sequential files or less-frequently-accessed content, since it has a higher random I/O overhead. 


When creating a new Storage Space, you can specify a maximum size larger than the amount of available physical space - the system will prompt you when the storage pool needs more drives to work with. Microsoft calls this "thin provisioning," which means that drive capacity is only reserved as you store data to the drive rather than all at once. You can also expand the maximum size of the Storage Space at a later point if necessary. Creation of these spaces can be scripted using PowerShell.

For an in-depth look at how this technology works (and a FAQ which answers, among other questions, some inquiries about its similarities to and advantages over RAID), check out the full post using the link below.

Source: Building Windows 8 Blog

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  • hechacker1 - Friday, January 6, 2012 - link

    Looking at the comments, it seems that you are able to specify the SSD in a pool as a backing device for the journal (specifically to speed up parity writes). All of this is done through powershell if you have a specific configuration in mind.

    But otherwise, the storage pool will tread all disks equally and just spread 256MB chunks over them.

    But it doesn't look useful for a system drive however, since you can't boot from a pool (at least not yet?).

    Still, using an SSD as a backing store might just give us built-in SSD caching to RAID 5 schemes for writes, which is pretty much RAID 5's major crux. I'd hope they also do read caching though (doubt it).
  • damianrobertjones - Friday, January 6, 2012 - link

    Ok... say you have the following:

    80Gb SSD: C: drive, system files
    750Gb HD: Re-directed movie/picture/documents folders

    You then ADD the following
    1Tb HD: Clean drive

    You then add this drive to the pool and windows copies/images your files to this drive. Your files are ALWAYS in two places at the same time.
  • Musafir_86 - Friday, January 6, 2012 - link

    -For those who want a bit more technical details on this, you may refer to these TechNet articles/blog posts (authored by the very same Mr. Rajeev Nagar here):

  • marc1000 - Friday, January 6, 2012 - link

    At home, I want my files in the disc I choose. Very few people need to expand a single drive letter over more than 1 disc. But at enterprise or some extreme cases, this could be useful.
  • B3an - Friday, January 6, 2012 - link

    Whats the point of having loads of individual disks? Do you like losing data and having slow speeds?

    With Storage Spaces, you get improved speed as it's a little like RAID-0, but you can also mirror all data, Even if one disk fails you dont lost any data and you can still access the drive as usual. You can even continue to add as many drives as you like. This is a killer feature for many people including home users. It also renders loads of software and hardware RAID solutions and similar setups obsolete.
  • marc1000 - Saturday, January 7, 2012 - link

    But how many people actually NEED over 2tb of data all the time, with fast speeds, at home? I have a simple setup for over 3 years now (100gb + 1tb), with games, dvd/br ripping, a few VMs to study, and never used more than 800gb at any single moment. Whoever wants to store tons of movies can use big slow disks or external storage. That's my point: very few people wil really NEED this feature.
  • B3an - Sunday, January 8, 2012 - link

    Why do you mention 2TB?? Because it's in the pics here? A storage pool can be of ANY size.

    Many people have important data on there PC's even if it's just family photo's or something. With this feature you could have for example a 200GB mirrored pool. Even if the speed isn't needed for some the data backup will be a big bonus and theres no bloatware or any other requirements to use it.
  • marc1000 - Sunday, January 8, 2012 - link

    Yes, the mirroring part is good. Easy and simple backup. I mentioned 2tb because now it's a common size for hdd's, so anyone could have one. The only people who will need more than this are the extreme users.
  • stevetb - Thursday, March 22, 2012 - link


    Wasn't that funny when Bill Gates said back in the 1970's that no one would ever need more than 2MB of storage space? Yeah, it cracked me up too!

    Oh just pretty much said the same thing......

    2TB is NOTHING for HD Video, even for a moderate user. If you are working with only 1TB then you are living in the 2000's. Time to evolve bud!
  • Ryan Smith - Friday, January 6, 2012 - link

    Well I'm certainly excited about this. Based on the technical description it's almost certainly a further iteration on the work MS had already done on Drive Extender v2. The chunk/slab description and how data is organized is practically identical, so clearly they didn't kill DEv2 as much as they held it back.

    Anyhow hopefully this means we'll see a WHSv3. 2011 has largely been a dud; the OS is fine and the backup client is really swell, but the lack of drive pooling seems to have killed a lot of interest in it as compared to WHSv1.

    It's interesting to note though that MS has done away with checksumming. DEv2 was to feature ZFS-like checksumming for each sector, but Storage Spaces leaves the checksumming up to individual programs. So techies looking for ZFS on Windows may come away disappointed, though I'm not sure filesystem checksumming is strictly necessary.

    The slab issue will also need to be better addressed, as it looks like we're going down the same path as DEv2 and chunks. If data is effectively being striped out, then in "non-redundant" modes you'd lose most-to-all of your data, since non-redundant modes are effectively RAID 0. Parity mode (RAID 4/5) will keep your data intact through a single failure, and of course mirroring (RAID 1) will go beyond that. In fact I'm not sure why mirrior/parity mode isn't forced on pools using multiple disks, as it seems like the use of slabs will make problems more likely.

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