Missing documentation, add disk to RADI6

Hi, I want to add a HDD to my RAID 6 which at the moment consists of 6 disks and no spare disk.

I am not able to grow the RAID in the GUI. The 7th disk does not show up in the window where I can chose disks to include them into the RAID. I tried to format it with EXT4. I tried to mount it. I also unounted it and deleted it from the list of file systems.

The documentation does not show a lot: https://openmediavault.readthe…est/features.html#storage

What is the right order to do this? Does a disk have to be formatted? Does it have to be mounted (probably not)? Does it have to be formatted and unmounted? Why is my disk not showing up?

And yes, I know I should have (could have) 2 spare disks with my RAID6 but I chose to wait until it fails and plug them in later.

I was able to add a spare disk via command line following this guide (without the conversion from RAID5 to 6 of course, because I already have RAID6): http://ewams.net/?date=2013/05…g_RAID5_to_RAID6_in_mdadm

However, I still don't know what the problem with the GUI was.