At the start of the year I moved a bunch of MKV files off the Drobo onto the 3TB drive hooked up to my Mac Pro.

Since then that 3TB drive has filled up, so I debated setting up a Drobo for my Mac Pro. I decided not to as the Thunderbolt Drobo's were last updated back in 2012. I'm holding off in hopes of a faster Drobo - the current Drobo's use the original Thunderbolt, while my Mac Pro has Thunderbolt 2 with twice the potential throughput.

So I decided to move those MKV files back onto the Mac mini's Drobo. I knew space would be tight so I ordered another 6TB Red over the weekend, after which I started moving the MKV files over to the Drobo. I got about half of them there when the Drobo changed the light by one of the 3 TB drives to orange, signifying that I needed to replace that drive with a larger one:

The 6TB was delivered today. I let it sit at room temperature for a couple of hours, then installed it:

That original time estimate of 39 hours is now down to 11 even though it's only been 5 1/2 hours. I suspect that's because Eye TV, the DVR software, was recording a couple shows at that time.

When I added that prior 6TB drive my usable capacity increased by less than 1 TB, this time my capacity increased by almost 3 TB. And, as I suspected, the Reserved for Expansion dropped to 0.