Servers can be configured with either single or dual redundant power supplies. Traditional workloads normally demand dual power supplies to protect against downtime in the case of a power supply or feed failure. If your Ceph cluster is large enough, then you may be able to look into the possibility of running single PSUs in your OSD nodes and allow Ceph to provide the availability in case of a power failure. Consideration should be given to the benefits of running a single power supply versus the worst-case situation where an entire power feed goes offline at a DC.

If your Ceph nodes are using RAID controllers with a write back cache, then they should be protected either via a battery or flash backup device. In the case of a complete power failure, the cache's contents will be kept safe until power is restored. If the raid controller's cache is running in write-through mode, then the cache backup is not required.