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December 4, 2007

2

Hard Drive Crash at Mozy

by Dan

Well, yesterday the hard drive in my computer at work failed. I find this more than a bit funny as I work at Mozy which is company that does online backups. It gave me an opportunity to experience the process of restoring my files first hand.

When arrived at work yesterday morning, I noticed that my computer was freezing for a minute or two at a time. I thought it was some run-away process on my computer, but didn’t think much of it at first. Eventually, it got annoying enough that I decided to reboot my computer to get rid of it. That was the last I saw of my computer.

Eventually, I did manage to get the computer to boot into “single-user mode” which is designed for diagnosing and fixing problems. A few obscure terminal commands later, I discovered that the file systems on both partitions on my drive were badly corrupted. For those interested, the super block and all of its backups were bad on both partitions. Not good.

Apparently, the crash was caused by a power failure or brown-out over the weekend. The company is a bit behind in getting backup power supplies (UPS) to all of their new employees. They have several on order, but it’s going to be a week too late for me. I’d been through 4 brown-outs so far this year and hadn’t had any problems. My luck couldn’t last forever, I guess.

Anyway, since I’d been using Mozy to backup my important files. I got to see how Mozy’s restore process worked and discovered a few things that could help the process go a lot more smoothly. Just after losing a drive, our customers are wondering if they’ll ever see their files again. Getting their files back quickly and easily would make them incredibly happy.

I use the Mac version of Mozy, so I’ll avoid commenting on the Windows version. We try to make both versions similar, but I’m sure there are some differences. So here’s the list for happy customers:

  1. Consistency — get the files back at all.
  2. Accuracy — get the files in their exact original state.
  3. Speed — get the files as quickly as possible.
  4. Usability — having a simple, easy, quick process for doing it all.

Looking at this list, it strikes me that this is probably the correct order in which to focus our attention. The Mac version does a good job on everything, but can improve on #2 and #4.

The current version of Mozy does not backup some types of files correctly, including symbolic links and resource forks. It also has some UI issues with bundles. These problems have already been fixed for inclusion in the next release and are in testing now. They were some of the last bugs necessary for Mozy to get out of it’s beta state.

UPDATE: Version 0.9 (and later) of Mozy supports resource forks, symbolic links, and bundles.

The main improvements needed before restoring files with Mozy can be a joyful process (“Yes, it worked!”) are:

  1. The ability to restore files to their original locations.
  2. An option to “synchronize” a folder by deleting files that don’t exist on Mozy’s servers.
  3. Support for restoring a “backup set” instead of just browsing for files.

Right now, it is possible to restore files to their original locations by choosing the root folder as the destination and selecting all of the highest-level folders for restoration. You get one warning about overwriting files. Since this is probably a very common desire (it’s what I wanted after my reinstall), I think Mozy should make it easier.

I also found that there were some default files and folders on my computer that I didn’t want after restoring. In particular, I had to delete the default files for iCal and Mail before restoring to make things work right. Since I knew that I’d backed up my entire Mail folder, it would have been awesome if Mozy could have restored my Mail folder to be exactly like Mozy’s copy of that same folder. There could even be some type of “merge” process that displays what Mozy is going to do (including files that will be overwritten) and ask for permission to proceed.

When you configure which files and folders you want Mozy to back up, you can choose to back up a “set” of files from a list or browse the filesystem directly. When restoring files, the only option is to browse. Since our website allows users to restore files by choosing from the sets they backed up, it makes sense that the Mozy application should too.

Overall, I was able to get my files back without too much trouble. Since I’m the one responsible for eliminating that “trouble” for our customers, I’ve added these ideas to our list of things to do. I don’t think I would’ve volunteered to destroy all my data just to see what it’s like, but maybe I should have. In any case, I hope to improve Mozy’s restore process soon.

2 Comments
  1. Paul
    Oct 28 2008

    Dan,

    Thanks for the insight. It’s nice to know that the system works in real world situations. I’ve been wondering though, if a hard drive crashes, does that at any time initiate the 30 day window of when the files get deleted? So in other words, if the client does not communicate with the server for a certain amount of time, do the files get marked for deletion?

    Thanks!

  2. Mar 30 2009

    (responding months later)

    No, it does not. The 30 day window doesn’t begin until a backup occurs where Mozy notices that the file is missing. So in the case of a crash, our service would just assume you weren’t backing up temporarily.

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