Having lost my Backup History – what I have learned

I have lost my entire backup history in Time Machine. It is really a disappointer, that this great backup solution has such a weakness. The following happened:

  1. I replaced my external harddisk (with 460Gb of data)
  2. I restored the data from Time Machine (took 8 hours)
  3. I turned on Time Machine again
  4. Time Machine silently deleted all previous backups because it considered the restored data as new and tried to make space on the backup drive.
  5. Time Machine did not delete the latest backup (ok, that’s good) but refused to continue.
  6. I deleted the backup of the external harddisk.
  7. Time machine crated a new bakcup (took 10.5 hours)

But the history is gone. The main reason is, that Time Machine lost the connection to the data which itself had restored. The reason is, that Tima Machine used the MAC adress of the computer and the UUID of the partition to refer to the disks being backed up. As I created the partition on the external drive using Disk Utlity, the UUID was different (no, I do not like UUIDs! Their benefit – if there is one – is really overestimated).

How could I avoid the loss of the history? There were various solutions:

  1. Do not use Time Machine to fill the new hardisk. Use Disk Utility to clone. Hopefully the UUID is also cloned. But I did not try …
  2. Manually delete the backups of the external harddisk (this would avoid loss of backup history for the builtin drives).
  3. After restoring the data, change the UUID of the backup to the one of the new partition as shown here:

    http://www.macosxhints.com/article.php?story=20090213071015789

2009-06-03: I tried to change the UUID. It was not successful!!

However it is, Time Machine could be improved such that restoring data is the same no brainer  performing the backing.

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