I've heard of a lot of people who fall into that trap with iDisk. The problem is that with iDisk set to auto-sync, it's not really a backup unless you can keep them from talking to each other. Once they do, they are identical, which sucks if the identical-ness is corrupt or missing. I didn't know about the Time Machine issues, but I guess that makes sense. I tell my clients to treat iDisk as a separate disk - that is, don't think about it living on your hard drive if it is on iDisk. Have a copy in your user documents folder (or wherever on your local drive that isn't iDisk) AND in iDisk - then you actually have 2 separate copies. And Time Machine will grab the local file successfully. Either way, sorry to hear about your loss!

This is also the reason why I get upset with people who suggest RAID1 as a backup solution. They argue that if one drive fails they can recover from the second drive. My argument is that if data corroption/deletion on drive one get replicated to drive two.

Time Machine backups are a totally different animal than iDisk syncing. The difference is between a "backup" and "synchronization". TM backups are unidirectional - your files get copied to an archive. When there's a conflict, a new version of the file gets saved. iDisk syncing is bidirectional. When there's a conflict, the most recent version of the file wins.

Basically, had Dan found a corrupt version of the file on a TM'ed hard drive, he could have gone through his TM backups until he found the uncorrupted version of the file (assuming he kept backups going that far back).

I used to keep all of my current working documents on my iDisk. Just before the MobileMe transition, I moved these critical files off the iDisk because I knew there was a potential for problems. I've still not migrated back to the iDisk, and it sounds like I've been unintentionally wise to do so.

But I do like having a copy of my most important files on my iDisk. It's another layer of backup security for me. I have my Time Machine backups plus a copy on the iDisk. I could lose my laptop and have my house burn down on the same day and yet still have the most important files I need to get work done.

Lately, I've been using Chronosync to accomplish this. Basically, I work directly with the files on my hard drive. Once an hour, Chronosync copies my ~/Documents folder to my iDisk. It then syncs in the background. I imagine I could have the same problem and Dan had, but I'd have TM backups of the files from my hard disk that I could go back to if necessary. And, if a file that's in use gets copied to my iDisk, the next hour that it's not in use, it gets copied to the iDisk again anyway.

Pardon me, but it seems that putting the primary file of an active database on idisk is like imagining that idisk is a database server, which it's not. I'm astounded that this scheme didn't fail in the first week.

And in terms of file corruption: it points to the wonders of hard copy. A pain to file and keep up with, but better than gold when the irreplaceable file goes zero k. All that is hindsight, and my condolences on the lost files.

I officially ditched iDisk (and all of mobileme) 2 days ago. I'm just sick of it. Way to many sync errors. I now have also moved to a low bandwidth part of the world, so it just didn't make sense to continue to pay for a service that didn't work.