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Ashik, Mac Technician
Category: Mac
Satisfied Customers: 11191
Experience:  Bachelor of Computer Application (BCA), 9+ Years of Experience in troubleshooting Macs, iPhone, iPad, iPod etc
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Hi, I have an external Lacie hard drive connected to my iMac

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Hi, I have an external Lacie hard drive connected to my iMac (and has been for around 2 years with auto-back-up performing without problems). Suddenly this morning, backing-up appears to have failed and had an error message stating that 'files cannot be copied on to back-up disk as it appears to be read-only' . it suggested to repair or re-format. In disk Utilities I attempted a repair which failed but as I am not a computer expert I am not sure how to re-format so any clues what went wrong? (by the way only 58 GB of an available 500 GB used on the external drive). It is connected via USB.
Hi and Welcome. My Name is XXXXX XXXXX I look forward to assisting you today with your question.

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Backup all of your important files from the external hd to your Mac and let me know once you did that, so we can format it. Remember, formatting will erase everything from the drive.
Customer: replied 5 years ago.
Hi thanks. I am sorry but how do I back-up all the external hard drive files on to the Mac. I guess the important files will be the music and photos. Everything else not critical
Just copy them to your Mac from the external drive. Select the files in the external drive, click and drag it to the internal hd of your Mac. Or select the file, press Command + C. This will select the files to be copied, then open your internal hard disk, open any folder you want the files to be copied and press Command + V. This will paste the files to the internal hd.

Then format it. Formatting is same as erasing the drive. Follow the steps below to format or erase it.

  • Open DiskUtility from Applications > Utilities folder
  • Select the External Hard Disk in the left column
  • At the “Volume Format” select “Mac OS Journaled/Extended”
  • If you confirm to format your hard disk, Click on “Erase” button.
  • That will erase/format it

Let me know if that didn't work, so we can continue troubleshooting. Don't Rate my answer until you are satisfied.

Customer: replied 5 years ago.
Ashik, I tried but as it was copying across my iTunes into a folder I created, another error message popped up saying drive (I assume the external) not disconnected properly. The external drive has now disappeared off my desktop (although still connected physically) and from devices listing - arrr! I can unplug the external and try re-connecting. Another question, everything on the external is backing up what I have on the Mac so can I just erase the external and start again without backing up or is that too risky? as the Mac HD is not affected by any of this - no?
Do you have the Musics and Photos on your Internal HD ? If so, then you can safely format it and start backing up again unless your hard drive is failing.
Customer: replied 5 years ago.
Yes, Ashik, there is nothing on the external drive that is not on the internal Mac drive and I am not aware of any problem with my Mac's drive. So I shall try and re-connect the external drive first - do not know why it keeps dropping off this morning.
Yes, just reformat it. This usually happens if the drive is failing. Try reformatting it and see if it works or not

Let me know if that didn't work, so we can continue troubleshooting. Don't Rate my answer until you are satisfied.
Customer: replied 5 years ago.
OK, have managed to re-connect (re-mount) the external drive, erased the data and I have started the back-up again but will take a while. The problem may have occurred if I didn't eject the external drive prior to a shut-down / re-boot (for example after a software update). Should I always disconnect the external drive prior to shitting down? Anyway will see if it manages to complete the back-up
Yes, but eject it before disconnecting. To eject it, just click and drag the hard disk's icon from desktop to trash and it will eject.

It seems like the file structure of your hard drive is corrupted. Let me know how it goes..
Customer: replied 5 years ago.
Ashik, it has completed the back-up successfully which is good news. It should be doing back-ups hourly so just want to see if the next one goes OK but looks like the problem may be solved. Will check back a little later.
If it backed up successfully, then there is no problem with your hard drive. It just the structure that corrupted and reformatting fixed it. I'm glad everything works now..

Don't forget to rate me Positive if you are satisfied.

Best Regards,
Ashik and 4 other Mac Specialists are ready to help you