[ceph-users] Re: HBA vs caching Raid controller

It's not a 100% clear to me, but is the pdcache the same as the disk internal (non battery backed up) cache?

Yes, AIUI.

As we are located very nearby the hydropower plant, we actually connect each server individually to an UPS.

Lucky you. I’ve seen an entire DC go dark with a power outage thanks to a transfer switch not kicking in generators. Then again two weeks later. Taught me to be paranoid about power loss. And with dual power supplies, to proactively check status, so that I don’t find out only when it’s too late that a cord unseated or a PSU died, resulting in a silent loss of redundancy.