Mad Props!

One of the most interesting, and most welcome, features of the recently-announced Windows Home Server is that it no longer uses drive letters. As you add storage (in the form of USB, ATA or SATA drives) they are simply added to a common pool of storage used by the OS.

Drive letters are an artifact of older operating systems, dating way back to (and before) the first versions of DOS. You can read a bit of a history of drive letters on Wikipedia here.

Today, most users know that "C" drive is their system disk, and that "D" drive is either a second hard drive, or an optical drive of some sort (CDROM, DVDROM etc). Further to that, there may be extra drive letters for attached devices such as USB hard drives or digital cameras.

The letters before "C" in the drive line-ups are more historical and less relevant than ever. Most modern machines don't even come with a fixed floppy drive, and hence don't have an "A" drive at all. Some of the first PCs I used had both a 5.25" and a 3.5" drive, allocated to "A" and "B" respectively. Later, the 3.5" drive became "A", and "B" was relegated to "virtual" status, mirroring "A" and useful only in copying floppies.

The idea of simply pooling data from multiple drives into a shared storage resource is something rather new to Windows. In the various unix flavours out there you "mount" new drives under a root folder (eg the "/usr" directory might be a completely separate disk from the "/bin" directory). This system still has limitations - run out of space on the disk allocated for "/usr" and you're in some trouble.

Windows Home Server takes a new approach - it mirrors anything and everything across more than one disk. If one drive were to fail, you know that you have a good copy of all data on the disk somewhere else. At a convenient time you can simply yank the faulty disk and insert a new one, and the mirrors are rebuilt accordingly.

This approach does have one obvious caveat: You have less disk space to play with, because everything's stored twice. WHS compensates for that by storing only one copy of each unique file from all the machines you're backing up, so the more PCs you're backing up, the better use of space you'll have. This is great for a shared backup device, but less useful if you're trying to use this shared storage pool as a single-machine resource.

My feeling, though, is that eventually it won't matter. Hard drive space is so cheap nowadays that it won't be too big an issue to buy two disks instead of one if you're worried about hardware faults. Ideally, a future version of WIndows that could make use of this technology would be smart enough to mirror the user's data, but not the system files or installed programs. After all, you can always reinstall a program, but I'm guessing you'd rather not retype that thesis.

So here's a call to arms (and I know it's not the first): Death to the drive letter! With any luck the next generations will only ever see a "C:" in the history books.