Hello all, We've had a Nautilus [latest releases] cluster for some years now, and are planning the upgrade process - both moving off Centos7 [ideally to a RHEL9 compatible spin like Alma 9 or Rocky 9] and also moving to a newer Ceph release [ideally Pacific or higher to avoid too many later upgrades needed]. As far as ceph release upgrades go, I understand the process in general. What I'm less certain about (and more nervous about from a potential data loss perspective) is the OS upgrade. For Ceph bluestore OSDs, I assume all the relevant metadata is on the OSD disk [or on the separate disk configured for RocksDB etc if you have nvme], and none is on the OS itself? For Mons and Mgrs, what stuff do I need to retain across the OS upgrade to have things "just work" [since they're relatively stateless, I assume mostly the /etc/ceph/ stuff and ceph cluster keys?] For the MDS, I assume it's similar to MGRS? The MDS, IIRC, mainly works as a caching layer so I assume there's not much state that can be lost permanently? Has anyone gone through this process who would be happy to share their experience? (There's not a lot on this on the wider internet - lots on upgrading ceph, much less on the OS) Sam