Unformatted hard drive

I previously used my Tablo without a hard drive attached and now want to add one to record shows. I plugged one in and it shows “Unformatted Storage” at the top, but nowhere to click to format it.

Under Settings, it shows “Storage temporarily unavailable”.

How can I format the hard drive to use?

What are you using to manage the Tablo, Chrome, Roku Android?. If not the Chrome browser try it. You should see the option to format the drive. in the Storage section on the Settings page. Try a power cycle with the USB Drive attached. The only time I ever added a drive was with it powered off then powered both up together.

I had the same thing showing “Storage temporarily unavailable”.
I fixed it with the app, a reboot of the device made no difference for me.
In the Tablo app, I selected the menu in the top left where it says “Settings”,
then I selected the picture of the Tablo at the top where it said “Unformatted Drive”.
Finally it gave me the option to format the drive. Success.