MacPro 6,1 cannot shut down

Status update.

I got a new disk, (LaCie 8TB RAID1) with both USB3 and TB3 connections.

As my old MacPro only has TB2, I had to get a TB2/TB3 adapter, which worked fine.

My old Disk (WD Duo 2TB RAID1) is now > 7years, so it was no big deal to replace it. Particularly since WD had the bright idea to build it specifically around the Green drive, which is no longer produced. So if this unit fails, it cannot be repaired.

Anyway, it turned out (probably) NOT to be the TB connection, but rather the fact that I had Dropbox running. I tested both with USB3 and TB, same behaviour. Dropbox prevented disk dismount, both at shutdown and even manually during session. An attempt to dismount the disk manually with Dropbox running made everything hang completely, and the system must be turned off by pressing the power button >5 seconds.

This is reported to Dropbox.

Now I am trying to find a way to automatically have a script terminate Dropbox (and wait for it) before shutdown or restart. Suggestions are welcome.

BN

Yes, 10.15.5.

As far as I know, there are (at least) four processes accessing my disk:

backupd

Dropbox

mds

and myself.

Any of these should in the best of worlds be able to finish what they are doing in time when they are signalled that a shutdown or restart is about to happen. It seems that one or more of them gets stuck, creating a system watchdog timeout.

Maybe I have a hardware problem not in the disk itself?

And about Time Machine backup, it seems that it is always busy during the day, I rarely see it being idle.

Maybe my disk is too big, my network too slow, or my NAS too slow.

Right now I have backed up 300GB out of 735GB, 14 hours remaining. Is this normal?

BN

Not sure the above was correct, more likely it was not.

The system refused to shut down with no Dropbox running, disk using USB3 connection..

Possibly, it could have been "backupd".

Back to square 1.

BN

Dropbox of course did not accept any responsibility.

Maybe they are correct, now I begin to suspect Time Machine...

If I turn off Dropbox, exclude my external disk from Time Machine backup, manually dismount external disks, make sure Time machine is not running, all before I try to shut down , it just MIGHT work.

My backup drive is a NAS and is always available.

The disk we discuss here is a local disk for documents, not a backup drive.

Ok, as I suspected.

I will wait for Dropbox's answer.

And use Dropbox only when needed.

Thanks for the advice.

So your recommendation would be to change to a USB3 disk?