To update ovirt 3.2.1 to version 3.2.2 you can follow next procedure:
If possible, backup engine, also you can backup all VM to export domain using oVirt console.
On oVirt engine node execute engine-upgrade
If engine-upgrade found new version of ovirt-engine-setup you will be prompted to update this package, do it, then run engine-upgrade again:
yum update ovirt-engine-setup engine-upgrade
engine-upgrade will stop oVirt engine, then back up database, then update packages and then start oVirt engine again.
If you used ovirt-engibe-dwh before, and seen message Error: Can't start the ovirt-engine-dwhd service while upgrading just restart ovirt-engine-dwhd service.
service ovirt-engine-dwhd start