And I can't see where to Erase it and make it APFS... only HFS+, MS DOS, Ex FAT... Thanks.

I did find 6.1b1. Is that what you referred to????

Thanks. That's interesting because I have a Drobo RAID that is working fine, but perhaps because it is more proprietary it does't look like a raid to ...

I had a typo... it hangs during its attempt to set up the volume and unmountS it.

Log doesn't go that far back... no problems, just wanted to make sure all drives are certified. Thanks for the reply.

I tried to attach it in the original post, but it didn't seem to happen. Let's try again.

Thanks.

OK, I unmounted the mirrored volume, pulled the drive I wish to swap and put it in the drive box, and started to certify it. It tells me it will take ...

We'll give it a try and get back to you. Thanks.

My problem wasn't in pulling the drive, but what I should do to place the new one in service. I've tried just "plugging it in" and run into problems w...

Here's the support file. Thanks! I had been removing the drive hot... and adding it's replacement hot. Maybe that's the problem?