External drive partition takes ages to mount

jonty1512 wrote:

Hi there

On my M1 Mac mini I have a 1TB Seagate M3 Portable USB 3.0 external drive which is connected directly to one of the USB A ports. This drive is divided equally into 2 500GB partitions, one for Time Machine and the other for media (formatted as ExFat so my other non Apple devices can access it) which is where I keep all of my music and video files. Recently after we had a power cut I have noticed that when I turn on my Mac mini the media partition takes an absolute age to mount, I'm not talking a few minutes here it can take anything from 30-40 minutes at best and sometimes it can take over 1-2 hours to mount. What is weird is that the other Time Machine partition on the same physical drive mounts immediately. I tried going into Disk Utility to manually mount the drive which fails. I have also tried running First Aid on the disk before it finally mounts and that fails as well.

Has anyone else had a similar issue? Is this because of the ExFat file format? I don't think that this issue is due to a physical problem with the drive as the other partition works flawlessly.

Like the idiot I am I have not noted down the error messages that Disk Utility gives when I try to either mount or run First Aid on the partition before it finally mounts, the next time I get this issue I will add them to this post.

TIA

John

TM likes its own dedicated drive and needs GUID/apfs—

if you are determined to partition, verify the TM is the 1st partition otherwise TM can struggle to find the itself when it queries the drive....

Learn more about backup disks that you can use with Time Machine —Backup disks you can use with Time Machine - Apple Support

Erase and reformat a storage device in Disk Utility on Mac

Erase and reformat a storage device in Disk Utility on Mac - Apple Support

jonty1512 wrote:

... Recently after we had a power cut I have noticed that when I turn on my Mac mini the media partition takes an absolute age to mount ...

A disk not behaving normally after a power outage is a telltale sign of damage. The fact that Disk Utility cannot even complete is a telltale sign of damage. It could be physical damage (which can affect only one partition, or all of them), or file system damage (can affect only one partition, or all of them). I think it is less likely that the Mac Mini or the cable were damaged since one partition seems ok and one seems not ok, that sort of points to the drive itself.

I would replace the drive. There could be other damage affecting your Time Machine backup partition as well that is not manifesting itself, yet. Keep the existing Time Machine that is on it for archive (in case you need it to recover something) but start a new Time Machine backup on a new drive. Dedicate the entire physical drive to Time Machine.

If you have time for a science project, you can get DriveDX to check the physical health of the drive but I don't think it is reliable any longer for backups nor for storing files that are important to you.