I'm new to OMV (Version 2.1.17). I Googled for this issue and also check this forum but the solutions offered did not solve my problem. What I did step by step is,
1. Wiped my all 3 physical disk (all of 3 are same products) securely. (Took about 9 hours)
2. Built a software Raid5
3. Created a ext4 filesystem belonging to my Raid5.
During this period, everything was ok and with no error messages. But, the mount button in filesystem menu is still disabled. I tried all the filesystems too... I tried to mount the raid via bash, but still can't be able to change the state of mount button.
I need your advice. I can an ssh connection for you to check also...