Backing up to Time Machine from an external drive

[Alwyn]

I discovered that, if I used Time Machine to do a backup from an external SSD it tried to back up the internal HDD as well and ran out of space. I know that it is possible to exclude files from a backup. Is it possible to exclude the entire HDD and just backup the external SSD.

If there isn't the only solution is to clone the SSD to the HDD, restart to the HDD and remove the SSD then do the backup.

 

[ferrarr]

If the Mac is booted from the internal drive, Time Machine will back it up. If the Mac is booted from an external drive, then you should be able to tell Time Machine to exclude the internal drive.

 

[Alwyn]

If the Mac is booted from the internal drive, Time Machine will back it up. If the Mac is booted from an external drive, then you should be able to tell Time Machine to exclude the internal drive.

Thanks. We have an 8 hour planned power cut today so I'll do it later on.

 

[Alwyn]

I clicked on the HDD and highlighted all the available components to exclude. Unfortunately System Settings fails to recognise that this is an ongoing backup. In other words it wants to add a new backup rather than make the necessary changes to the existing one. I believe that it is possible to rectify this but how is it done?