Clean firmware and 1&2TB -> 3TB questions

Before you install the 3TB drives, you need to update to 4.2.17. The Beta of 4.2.19 is out, but I would hold off unless you need some of it's features. Once you have upgraded to 4.2.17 you will be on GPID rather then MBR formatting and I don't think the 4K sectors are a problem as the conversion process may take care of it. You can then add the 3TB drives one a time. You do not need to go through all the in between versions, unless you just really need to burn some time. My one NVX was originally on 4.2.9 and the other I think was 4.2.11. I upgraded both to 4.2.12 and then to use the 3TB drives I upgraded again to 4.2.17.

I have had no problems with a mix of 3TB advanced format drives and 1TB traditional drives. (I did lose another 1TB, but that one was on my NV+).

I once had a fellow who worked for me in accounting when I was in Virginia. He always said when making big changes it best to wear a belt and suspenders. I kind of like that philosophy. If you have data that could be put at risk if something goes wrong with the upgrade and expansion, it would be prudent to update your current and complete backup. (Or at least the backup of critical and important files). I did one of my NVX units and then two weeks later the second, and I started with the backup unit first.

I'd recommend having a read of What to do before expanding your ReadyNAS volume

PapaBear don't confuse GPT partitioning with 4k sector alignment. They are two separate things.

You don't need to factory reset to get 4k sector alignment. Take a look at Why you might want to factory reset a x86 ReadyNAS

Thanks for the clarification on the expansion. And after reading the guide, I am weighing a factory reset, although it would involve a lot of disk juggling.

How about clearing the firmware thought? Specifically I installed vmware, which I use in .15, but isn't compatible going forward. I'm afraid it could cause a crash during an upgrade, and I know for a fact that it survives os reinstall, so would I have to manually remove it?

You'd manually need to remove it.