Good morning, Ceph was installed on Ubuntu Server 24.04 with cephadm. The cluster consists of 4 nodes; the first one also acted as a monitor in the initial state, but as all the others were added, in addition to being OSD hosts, they also acted as monitors. These machines had the major flaw of not having the operating system disk in RAID, and after 20 days, 3 nodes failed. The OSD disks are fine... I tried reinstalling the system on one node and recreating a monitor using the data taken from /var/lib/ceph/osd/, but I don't see the OSDs. This is the situation… thanks for the support. -- Napoli Francesco Gruppo Reti e Sistemi Informativi Istituto di Fisiologia Clinica - CNR Tel. 050.315.2344