When I was running OS X 10.15.4, and using a ThunderbBay 4 and ThunderBay 6, both RAID 5... I saw this lockup on the ThunderBay 4 frequently when copy...

Same bug. I do not know of an easy way to go back, as the "snapshot" feature which made this easy using Time Machine apparently is also broken. ...

This is a bug introduced in 10.15.4. We are working with Apple engineers to help find a fix for 10.15.5, or find a workaround. I started gett...

Thanks for this thread, I was wondering the same.

Thank you for your detailed reply.

For what it’s worth, Drobo enclosures have this ability (to add drives to expand the RAID size at later points), but man... stay away from that crud! ...

Thank you for the reply. I also have read a bit on the topic, and most people agree on two things: 1) spindle bearing wear is the major player in ...