Last weekend I found some blog posts by a blogger who calls himself "Fear the Cowboy" discussing some of the more severe technical limitations that RAID (especially RAID 5) has compared to Windows Home Server Drive Extender. Check out his posts here.
His posts got me motivated to write this one, which I've been meaning to do for quite some time...
When we were thinking of building the Windows Home Server product and doing focus groups we'd ask consumers "what do you know about RAID". Uniformly the answer was (at least in the U.S.) "Oh, that's a insect repellant".
Geeks & IT professionals know RAID stands for "Redundant Array of Independent Disks" and is a storage technology widely used in the corporate IT world.
Those same geeks, when encountering Windows Home Server for the first time, often ask the question "Why doesn't Windows Home Server use RAID?". The simplest answer is RAID sucks as the basis for a consumer storage product. But, my PR team would rather I not say it in such a negative way. Instead, they want me to say something positive like:
"Windows Home Server is a consumer product that provides an amazingly powerful yet super-simple to use solution to centralizing a mutli-PC household's storage. Windows Home Server includes a new, revolutionary storage technology we call Windows Home Server Drive Extender that kicks RAID's butt."
Or something like that.
Seriously, Windows Home Server does provide an amazingly powerful solution for the storage of a family's digital stuff. This solution is exposed to users in the household as Windows Home Server Shared Folders and to the person who sets up the home server as Windows Home Server Storage.
Server Storage is where the person who sets up Windows Home Server (we call this person "Jeff" by the way) can add or remove hard drives to/from Windows Home Server. "Jeff" accesses this functionality through the Windows Home Server Console. "Normal" family members (such as "Jeff's" daughter who we call "Samantha") don't know or need to know anything about Server Storage. Once a home server is set up, Server Storage is "just there" being useful. Like air. For you geeks, the underlying technology is Windows Home Server Drive Extender, which is really the focus of this blog post.
Shared Folders are literally just that: file folders stored on the server but shared out to home computers. Family members access them using standard Windows (or Mac) interfaces such as Explorer and other applications. "Jeff" can change settings on shared folders if he really needs to, but the system is designed to "just work" for most families out of the box. For the geeks reading this, the underlying technology in use here is SMB/CIFS. Windows Home Server Remote Access makes it easy to access shared folders from outside the home using a standard web browser as well.
On the surface, various RAID technologies purport to meet some of the requirements we set for the storage system for Windows Home Server, which were:
Windows Home Server storage system design requirements
- Must be extremely simple to use. Must not add any new concepts or terminology average consumers would not understand. Simple operations should be simple and there should not be any complex operations.
- Must be infinitely & transparently extendible. Users should be able to just plug in more hard drives and the amount of storage available should just grow accordingly. There should be no arbitrary limits to the kinds of hard drives used. Users should be able to plug in any number of drives. Different brands, sizes, and technologies should be able to be mixed without the user having to worry about details.
- All storage must be accessible using a single namespace. In other words, no drive letters. Drive letters are a 1970's anachronism and must be squashed out of existence!
- The storage namespace must be prescriptive. In other words, our research told us that consumers want guidance on where to store stuff. Our storage system needs to be able to tell users where photos go. Where music goes. Etc...
- Must be redundant & reliable. There are two components in every modern computer that are guaranteed to fail: fans and hard drives. Because they have moving parts, Windows Home Server must be resilient to the failure of one or more hard drives.
- Must be compatible. Compatible with existing software, devices, disk drives, etc...
- Must have great performance.
- Must be secure.
- Must enable future innovation. Both the amount of storage consumers are using, and capacity/$ are growing at Moore's Law like rates (while nothing else really is). This creates a discontinuity in the industry and an opportunity for innovation. The storage system must operate at a higher level of abstraction to enable rich software innovation (file level vs. block level).
It turns out that no RAID technology (I almost wrote "solution", but there is no such thing as a "RAID solution", it's just a big mish-mash of technology) met more than a few of these requirements when we first started building the product.
So we designed an innovative new technology called Windows Home Server Drive Extender and we have shipped that technology as part of a complete solution in Windows Home Server. The Windows Home Server solution meets all of these requirements. And it kicks butt.
Did you know you can get a free evaluation copy of Windows Home Server by going here? For many geographies we'll ship it to you for free as well. Install it on some old computer (the resource requirements are pretty meager; an old PIII with 512MB of RAM will work great) and throw a bunch of hard drives at it to see just how great a job it does.
Or skip the "free crack" step and just dive in and buy an OEM product.