Dave McCabe at the Home Server Show invited the BYOB guys to sit in on podcast #124 and talk about storage for Windows Home Server. He asked me to whip up a short sermon comparing the storage technologies in both versions and talk about it on the show. I can do short. I think.
Windows Home Server v1
As we all probably know, Windows Home Server v1 uses a technology called Drive Extender. DE, as we now call it, allows you to add additional drives to a WHS v1 to create a storage “pool” of drives appear to the user as one large drive. On the User front-end, WHS v1 is divided into two partitions. There is a 20GB C: drive for the OS and the rest of the space creates a D: drive that works as the data storage area. There is of course more to it behind the scenes, but this is it from a user POV. You can add and remove drives at any time without concern about size, type, manufacturer or connection type. Adding and removing drives is done through a special wizard and is easy to perform. Remember, DE is a software solution to storage pooling and is not RAID. As a matter of fact, from the start of WHS v1 Microsoft has highly discouraged RAID with DE citing severe problems .
In addition to DE, WHS v1 also offers Folder Duplication. When enabled, Folder Duplication offers data protection by keeping copies of your files on two different drives in the pool. If one drive fails, Folder Duplication will have a copy of the files from the failed drive safely stored on the other drive in the pool.
The user files are moved by a background service called DE Migrator. The Drive Extender Migrator service runs and then takes an hour break under normal conditions. It is not run at specific times although you can be sure it will run after key events like drive replacement, switching of Folder Duplication and WHS start up.
This next part is a quote directly from the Microsoft White Paper “The Windows Home Server Drive Extender Migrator service has three major functions:
• To duplicate certain files
• To migrate files that are not already migrated
• To manage the storage across the hard drives
The filter is not always able to migrate files when they are added to the home server, but the Migrator service runs in the background, looking for files to migrate. If a file is in a shared folder that is configured for duplication, the Migrator service selects a second hard drive to store an alternate shadow.”
The data on your drives move around. All three images below show 1.36TB of free space but show how DE masks the actual locations of the data.
Now, from what I just talked about in WHS v1, you can see advantages and disadvantages based on the WHS v1 design and drive technologies and apply it to your own situation.
There were also a few rudimentary limitations of WHS v1 due to its software, code base and 32-bit addressing that caused problems in areas such as drive size limits, backups and restore drivers.