Apple's Time Machine backup system has been working mostly flawlessly for me for the past couple of years.
But two or three days ago, a dialog box suddenly appeared on my screen:
Time Machine completed a verification of your backups. To improve reliability, Time Machine must create a new backup for you.
That doesn't sound so bad, right? But it is. What it really means is this:
Time Machine has found an unrecoverable error in your backup set. Therefore, if you want to keep using Time Machine with this backup disk, then you have to completely erase your entire backup history and start over from scratch.
It really doesn't explain very clearly that that's what it's going to do, but it is.
And the only buttons in that dialog box are one that tells it to wait 24 hours (performing no backups in the meantime) and ask again, and one that tells it to proceed with wiping the backup history.
So I'm archiving my Time Machine backups to an external disk just in case (it's entirely possible that there's still something salvageable in them; I wouldn't do a full restore from that archive, but if there are files I need, I'll look for them in it), and then I'll wipe my backup history and start over.
I'm pretty sure that I encountered this error message once before, but I can't find any record of what I did. Which is why I'm posting this blog entry.
Dear Future Jed: If you're reading this, it probably means you've encountered another backup verification error. Sadly, you didn't find a way around this, so don't waste time looking for one. Just archive your backup history to an external disk and start over.
On the plus side, this means I won't have to do a longstanding item on my to-do list. I had discovered that I couldn't change the name of my hard drive without losing access to the backup history of my previous computer, so I've been meaning for months to find out if there's a way to preserve access while still changing the hard drive name. Now I don't need to do that; I'll just change the disk name before I start backing up again.