I am trying to back up my (model 2011) MacBook Air to a 1TB Seagate portable drive. I have 159GB on the MB Air. When it gets to roughly 4-5GB (amounts vary widely) it stops and says it cant back up to the drive. Suggestions?
There could be something wrong with your Mac internal drive, or with the external drive, or with the cable.
First, I would run Disk Utility First Aid on the Mac internal drive.
Second, I would download DriveDx and have it check the physical condition of the internal drive.
Third I would run Disk Utility First Aid on the external drive. Note that the external drive must be formatted GUID HFS+ to be used for Time Machine. If it is formatted different, reformat it and try Time Machine again.
If possible, try DriveDx on the external drive (some external drives do not support the diagnostics).
If everything checks out, try a different cable.
You can also try a different external drive. You can also erase/reformat the existing (or the new) external drive with GUID HFS+ and try again. First remove the drive from Time Machine, after reformatting the external drive, add it back and try again.
There could be something wrong with your Mac internal drive, or with the external drive, or with the cable.
First, I would run Disk Utility First Aid on the Mac internal drive.
Second, I would download DriveDx and have it check the physical condition of the internal drive.
Third I would run Disk Utility First Aid on the external drive. Note that the external drive must be formatted GUID HFS+ to be used for Time Machine. If it is formatted different, reformat it and try Time Machine again.
If possible, try DriveDx on the external drive (some external drives do not support the diagnostics).
If everything checks out, try a different cable.
You can also try a different external drive. You can also erase/reformat the existing (or the new) external drive with GUID HFS+ and try again. First remove the drive from Time Machine, after reformatting the external drive, add it back and try again.
Backing Up with time machine
