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An external hard drive that I had been using to hold backups for my MacBook Pro does not show up in the Finder sidebar when I connect it to my new MacBook Air. It also does not appear in the list of available disks to select in Time Machine. I've ensured that Hard Drives is selected under Finder Preferences. The device does appear in the USB list under System Information. How can I get Time Machine to recognize this drive?
MacBook Air (2020 or later)
BradHolt wrote:
I launched Disk Utility and it found the external drive but said it was unmounted. I tried to mount it with no success. I then tried running First Aid but that failed. I then ran Restore and that failed, but the disk suddenly mounted, but still didn't show up as an available drive in Finder or Time Machine. I tried to Eject and a message popped up that it couldn't be ejected because it was in use.
The external drive MAY be damaged. How old is it? Can you try it on another computer.
I say MAY be damaged because there are other possibilities. When Disk Utility finds the drive but it shows up unmounted, that can happen when the MacOS detects a problem with the drive and automatically launches fsck to try to repair it. This (fsck) can run for a long time, possibly hours, if this is a backup Time Machine drive with many files. While this is happening the drive remains unmounted and the light blinks indicating drive access is happening. If you somehow get it to mount before fsck completes the disk mount might be unstable due to unresolved errors or damage and very slow, requiring many retries, hence it appears "busy" or "in use" as it tries and retries even the simplest of tasks.
Sometimes a damaged drive will not work on one computer but barely function on another. Can you try another computer somewhere? It might also be due to a problem with the new computer or one of its ports, in which case it would work on another computer. Also, I would try another cable/connector, those are the cheapest part of the chain and sometimes fail. What type of USB cable is this (USB, USB 3, USB-C ...), and is there an adaptor used as well (try a different adaptor).
BradHolt wrote:
I launched Disk Utility and it found the external drive but said it was unmounted. I tried to mount it with no success. I then tried running First Aid but that failed. I then ran Restore and that failed, but the disk suddenly mounted, but still didn't show up as an available drive in Finder or Time Machine. I tried to Eject and a message popped up that it couldn't be ejected because it was in use.
The external drive MAY be damaged. How old is it? Can you try it on another computer.
I say MAY be damaged because there are other possibilities. When Disk Utility finds the drive but it shows up unmounted, that can happen when the MacOS detects a problem with the drive and automatically launches fsck to try to repair it. This (fsck) can run for a long time, possibly hours, if this is a backup Time Machine drive with many files. While this is happening the drive remains unmounted and the light blinks indicating drive access is happening. If you somehow get it to mount before fsck completes the disk mount might be unstable due to unresolved errors or damage and very slow, requiring many retries, hence it appears "busy" or "in use" as it tries and retries even the simplest of tasks.
Sometimes a damaged drive will not work on one computer but barely function on another. Can you try another computer somewhere? It might also be due to a problem with the new computer or one of its ports, in which case it would work on another computer. Also, I would try another cable/connector, those are the cheapest part of the chain and sometimes fail. What type of USB cable is this (USB, USB 3, USB-C ...), and is there an adaptor used as well (try a different adaptor).
Connected via USB cable directly to the MBA. I had a backup of my damaged MacBook Pro on the Toshiba external drive that I restored to the new MBA. No problem at that time with the MBA recognizing the external drive and accessing it. But now it doesn't. I found another thread about a similar problem and that user was advised to use Disk Utility to repair the drive. I launched Disk Utility and it found the external drive but said it was unmounted. I tried to mount it with no success. I then tried running First Aid but that failed. I then ran Restore and that failed, but the disk suddenly mounted, but still didn't show up as an available drive in Finder or Time Machine. I tried to Eject and a message popped up that it couldn't be ejected because it was in use.
Yes. The MBP fell on a concrete floor and broke the display. I can't figure out why the MBA had no problem with the Toshiba drive before the restore, but now won't recognize it. The light on the Toshiba comes on when I plug it in and then flashes continuously.
Agree with presentation of @ steve626 - the drive may have been corrupted or worse - failed.
Attach to even a Windows computer - which will complain the drive is not readable - but at least is is aware the drive is alive.
The Partition Map of the drive sometimes gets corrupted. It may require Erasing the Entire Drive - all Data will be lost - and reformat say in exFat with Master Boor Records on an Apple Computer. Ten move if over to the new MBA M1 and see if it is mountable. If yes, that was the issue - corrupted Partition Map. Now, reformat it on the M1 computer back to APS / GUID if going to use it as a Time Machine Backup drive.
Many thanks to P. Phillips and steve626! I connected the Toshiba external drive to a Windows PC laptop and it was able to "see" the drive with its disk utility tool. I don't remember how or where, but I found an application called EaseUS Data Recovery Wizard Professional that was able to analyze the drive and diagnosed a "lost" partition. This app was then used to recover the data on the drive and to repair the partition. I then formated the drive and the PC found it usable. Much to my surprise, when I next connected the drive to my MacBook Air, it appeared as a usable drive and is now ready for use again for my macOS backups! I'm grateful for all the replies to my posting and the thoughtful suggestions.
Welcome.
Have used EaseUSPartition on a Windows computer and yes it worked to increase a Partition on the Windows machine they able to do the Drive Image to external drive. Sort of Windows version os a Clone on MacOS.
Though, caution should be offered. The drive is now Usable on macOS but may still be iffy at best. One should be formatted as APFS and GUID Partition Map if using for Time Machine Backup.
The new MBA is an M1 unit ?? How is the USB Drive being connected to the MBA ?? Is there a USB Hub being used or directly connected to MBA ??
in addition to P. Phillips' questions:
how is the drive formatted?
are you using any software provided by the drive's manufacturer?
I don't know how it's formatted, but it was working fine when I did a restore of a backup on that drive to my new MacBook Air. Not using manufacturer's software.
was the failed MBP and the new MBA both running macOS big sur?
Thanks, P. Phillips! I'll follow your suggestion.
MAC not connecting to external drive?
