Windows Home Server: where’s the backup plan?

Microsoft has put out a public beta of the forthcoming version of Windows Home Server, codenamed “Vail”. As always the rules of beta software apply – it’s probably quite buggy, certainly incomplete, and it might manage to totally ruin your day. If it were ready to ship it would have shipped, not gone into beta.

You might recall that I have a soft spot for Windows Home Server (WHS), and the dedicated HP server on which I first got hold of it. It added a useful amount of functionality to my home network, and it can potentially introduce important facilities such as proper backup and restore, file sharing and media management to people who have never had a server before. It was designed to be run as a headless server without a screen, keyboard or mouse, and to be stuffed into a cupboard under the stairs and forgotten.

You can’t just pull a disk out of your WHS box and mount it into a normal PC

WHS got off to a rocky start, and it was its innovative file system that caused the upset, making it possible for data to be lost under certain circumstances. That was obviously somewhat suboptimal for an operating system aimed at non-technical users, and Microsoft made things worse by not exactly being lightning quick in coming up with a fix. But once it was finally fixed, it became clearer how much the platform had to offer.

A key component was the file system, which took NTFS and grafted onto it a new file system driver that allows all the storage in your server to be viewed as a single pool. Add more disks and this pool gets bigger, and you can mark files and directories as being of special importance, in which case WHS ensures they’re stored on at least two different spindles as a precaution against drive failure. This technology has never appeared on any other Microsoft platform, and I wondered whether it was a good idea that would never reach fruition.

Those concerns weren’t without foundation, because it seems that for Vail Microsoft has decided to ditch that design and come up with something else. This new version is block-based rather than file-based, and again it exists as a file system driver buried deep down inside the file system stack.

Microsoft claims that this new design is much better (a claim to which Mandy R-D clearly applies) and far more compatible with applications that might do somewhat naughty things with the file system. The downside is that your data isn’t readable at all unless you have this new file system running, so you can’t just pull a disk out of your WHS box and mount it into a normal PC.

That sort of thing makes me nervous. I treasure the ability to take any disk from a dead box and mount it somewhere else. You can take a multidisk array out of Windows Server and plonk it onto another box – and it will even remember its drive letters, for example.

This is quite a major step away from compatibility, and it’s going to be important that Microsoft provides the flexibility to allow for routine backup/recover and disaster recovery solutions to be custom written for Vail in the future. It would be a real pity if Vail, which is supposed to provide all of your home desktop machine backups, were not capable of being backed up itself.