Time Machine keeps backing up to wrong external hard drive

Question

I had TM working fine for several months with my LaCie external HD named "LaCie" via Firewire 800. I bought a larger LaCie HD, daisy chained to the open FW800 port on "LaCie", named it "LaCie 1TB" and moved the "Backups.backupdb" folder to it using the Disk Utility restore function per several posts found here. I changed TM preferences to point now to "LaCie 1TB" and everything worked.
Then I deleted the "Backups.backupdb" folder from "LaCie" and renamed the HD "LaCie 500". I moved my video files there and changed TM preferences to delete "LaCie 500" from the "do not backup" list. I reran TM and it again worked including backing up "LaCie 500".
Now the problem. Whenever I first turn on the external HD's, TM immediately begins making a new backup on "LaCie 500". I stop it. If I then select "Back Up Now" in TM, it correctly backups to "LaCie 1TB". I always delete the "Backups.backupdb" created on "LaCie 500". And it always repeats this at the next HD restart but always works correctly if the drives are already turned on when the next backup time is reached.
Is this a bug in TM or is there something I can do to stop it other than hooking up "LaCie 1TB" to a FW400 or USB port and making sure I turn it on first? I don't want to do that. Seems it should only backup to a drive named the same as the name selected in TM preferences. I have other drives to hook up too so it could get worse. Thanks.

Answer 1

Pondini wrote:
Just how did you do that? Did you erase the volume with Disk Utility, or use the Finder?
I just erased it with the finder.
So tonight I turned off TM and deleted the two preferences files. I turned TM back on and set it up again. It said the next backup was in a few minutes so I shut down the drives and waited a few minutes. I restarted them and nothing happened. I checked TM and it now said the next backup was in about an hour. I turned them off and on again and nothing happened. I also restarted the computer and the lock on the TM prefpane was unlocked again so that isn't fixed.
I then used some other tools I had and found a hidden file named ".001ff35b9356" on both drives. The file contents were:
V∞=„:ïA
Ç ıE…· ‰
I deleted this one on the first drive, "LaCie 500". I also noticed they both had a file called ".com.apple.timemachine.supported" on them but I left that alone.
I shut down and restarted both drives. Neither one mounted. So I shut them down again and this time they both mounted. TM did nothing. I had previously noticed that the icon for each of these drives changes to a time machine icon instead of the standard hard drive icon. For comparison I attached another old external drive I had and its icon stayed the standard hard drive icon. It also had the ".com.apple.timemachine.supported" file on it but not the ".001ff35b9356" file on it.
I shut both drives down and waited for the next scheduled backup time to pass. I started them both up and again nothing happened and TM said the next backup was another hour out. I told it to back up now and it worked. So I'm not sure now what is happening. It isn't automatically backing up at all when I first turn on the drives. It seems just to push the next backup out an hour if they aren't attached when the times comes. I don't know how it's supposed to work. I thought it would start a backup immediately if it was overdue. When the drives are off TM says the next backup is "When disk is connected" but that isn't what it does now. I guess I'll use it for a while and see what happens next.
This shouldn't be this hard. Thanks for your help.