MacOS – Prevent OS X from seeing a disk previously used for Time Machine as a TM disk

backuphard drivemacostime-machine

I have a slightly flaky old disk which was once used with Time Machine on an old Mac. Since Time Machine is no longer part of my workflow, I'd like to just access this disk like any other HDD. Currently, when I try to delete files I receive the message "The operation can’t be completed because backup items can’t be modified."

Edit: I tried using tmutil associatedisk, but I don't see any old versions when I "Enter Time Machine".

Best Answer

There is a command named bypass that should allow you do remove Time Machine related files. This command should precede the rm command.

The path to the bypass command is given below.

/System/Library/Extensions/TMSafetyNet.kext/Contents/Helpers/bypass

An example is given below.

/System/Library/Extensions/TMSafetyNet.kext/Contents/Helpers/bypass rm -f /path/to/file/name

There also a service written by a third party that allows you do execute the bypass/rm commands from the Finder application. If interested, I could provide a link.

Related Solutions

Mac – faster way to copy time machine files from one disk to another

A normal copy (or copy via rsync or ditto) will not replicate a Time Machine fully as it will convert two directories linked together (as occurs in successive TM backups with no change between) into two separate directories.

The best way is to copy the whole the disk using Disk Utility or the block copy part of Carbon Copy Cloner and probably similar on SuperDuper.

MacOS – Unable to Access Local Snapshots when external Time Machine is disconnected

I have seen this on several occasions and I have done this to clear up the corruption or glitch that prevents browsing local snapshots without an actual full time machine destination mounted:

Connect to one of my destinations and force a good backup
```
tmutil startbackup --block --rotation
```
Disable local snapshots
```
sudo tmutil disablelocal
```
Enable local snapshots - being sure the cleanup is done
```
sudo tmutil enablelocal
```

I do watch the console app (or tail -f /var/log/system.log) during the backup and commands above to make sure that the local filesystem gets cleaned up and give the computer several minutes between the disable and the re-enable since it does have to unmount the network filesystem, delete old copies of files and clean up things before trying again with a local snapshot.

The downside of this is you do lose any copies of files that only existed on the local snapshot intervals and didn't get saved to an actual remote location. It also doesn't really dig into why the store became corrupt so you might have the same thing happen again at a later date. I've also had good luck with reproducible time machine problems reporting it to Apple for assistance. They'll want you to run tmdiagnose and probably not reset things like I mentioned above if you want to get at the root cause of what really happened as opposed to getting it working again.