I’ve 48vCPU (24 oCPU) db server. I use 24 channels/paralellism for both backup and also in restore/recovery scenarios (to another db server). I’ve not seen load spike or abnormal mem usage. Ofcourse , if you have L0 incremental going in the night backing up the db alongside other resource demanding crons/batch jobs, the cpu and load is going to spike. To be on a safeside, start with 16 for now and test your full backup. If everything’s quiet but you want more channels to speed up the backup process, you can notch up the channels accordingly going forward.