Backup vSphere Cluster with ghettoVCB
The ghettoVCB script is a well known free backup solution for standalone ESXi Hosts created by William Lam. The script works with ESXi 3.x up to ESXi 6.7. It does not support vCenter or cluster backups out of the box but with a little workaround, you can backup virtual machines in a DRS enabled cluster. I'm using this type of backup for a couple of months without issues.