I'm running macOS Big Sur Public Beta 5 (20A5354i) on the MacBook Pro 16" 2019. I have several external drives, a mix of SSD and HDD. I'm using them for Time Machine as well as the storage. The HDD is GPT with HFS+ while SSD is formatted with GPT APFS with two containers. All drives have encryption enabled. The problem I'm observing is that during the heavy load (like copying ~1TB of photos from one drive to another, or from internal to the external) OS may experience freezes, the external disk connection drops, etc. Once such even occurs, the whole disk subsystem becomes unstable: can't eject the disk (resource is busy, which it is not), random system freezes are experience when disk operations are involved (either internal or external), data corruption on external drives, especially if I have to unplug them without unmount (which doesn't work because of above). I'm curious if this is my setup and drives (unfortunately Big Sur doesn't allow external drivers SMART checks) or the OS in general and others also have similar issues with the disk subsystem performance and operations.