Originally from the User Slack
@Johannes_Gilger: I am getting an error when trying to run nodetool on a running node:
what(): Could not setup Async I/O: Resource temporarily unavailable. The required nr_event (1) exceeds the limit of request capacity in /proc/sys/fs/aio-max-nr (1048576)
I have a 32-vcpu node and aix-max-nr set to 1048576. I don’t know why I’m getting this error, it works fine on other nodes with the same configuration. It’s just two out of six nodes that throw this error.
Oh, hold on, another node has 2097152. Hmm
@Johannes_Gilger: Mystery solved, don’t mind me 
@Robert_Bindar: If you’d like to share what was wrong, it’d be highly appreciated, others might search the chat in the future and find this helpful, cheers!
@Johannes_Gilger: Well the aix-max-nr was too low on three out of six nodes
Set it to 2097152 now and it works