I want to repair my Mac using disk utility. I have a backup from timemachine saved on to an external hard drive. My question is if I use the external hard drive back up to restore my iMac will the process damage or erase anything else that is saved on the external hard drive?
iMac
Restoring from Time Machine should not damage or erase the external hard drive.
see > Use Time Machine to back up or restore your Mac - Apple Support
However, it is always a good idea to have a second backup just incase something should go wrong.
For years, I use a multiply backup strategy which include a Time Machine backup, plus daily and weekly Clones made with CarbonCopyCloner.
. My question is if I use the external hard drive back up to restore my iMac will the process damage or erase anything else that is saved on the external hard drive?
No the EHD should be okay. However many experienced users have 2 backups, because backups can fail too. In other words, sometimes redundancy is wise. For the second backup, many use a bootable clone. What I'd recommend is once the internal HD is fixed (or replaced) and you have restored from your TM backup, then make a bootable clone backup on a 2nd EHD using either SuperDuper or CarbonCopyCloner.
Thank you very much my machine is up and running again. I will take your advice and make a bootable clone on a 2nd EHD.
Thank you very much. My machine is up and running again.
My iMac won't start up
