Flexible number of nodes in a Proxmox cluster

Hi,

I'm using a Proxmox cluster with 6 nodes (HP DL360 Gen8 servers) on which also a Ceph cluster is configured. Is it possible to flexible power-off nodes in times where less performance is used and power them on again when I need the performance? In my scenario I would like to power-off 3 servers out of 6 to save energy costs. Is that possible and even recommended with retaining a healthy cluster state (Proxmox + Ceph)?

Thanks for any input,
hoba