My bad, UI has scroll down, which is not that visible. Add disk is there!

BTW, you can config the disks for nodes without Longhorn GUI: https://longhorn.io/docs/1.4.0/advanced-resources/default-disk-and-node-config/

Thanks Shou, where exactly should I put second longhorn disk (mounted at /mnt/longhorn2)? Via GUI I just put /mnt/longhorn2 and click on Schedule, in command line it is not that obvious for me.

No. You can mount your new disks on any path then set the path as a data path (Longhorn disk) for the node.

Okay, but where exactly should I put that new disk path? One disk is easy, mount drive as /mnt/1 and bind mount it to /var/lib/longhorn When I have /mnt/2 where should I add that thingy? 10x

You can directly use

/mnt/2

as a new disk of the Longhorn node.

Yes, but where should I specify it on the server, using command line (without using UI)?

You can try

kubectl -n longhorn-system edit lhn <Node Name>

Aha! Allright, I missed that (if it is spec'd in doc). Thanks Shuo