It is advisable to run an odd-number(at least 3) of monitors but not mandatory. A 2 monitor cluster can also provide service. I think it's ok to shutdown a monitor host for a while. If you are afraid of monitor down when maintaining, means that only 1 monitor is alive in the cluster which makes the cluster unavailable, I think you'd better add 1 or 2 temporary monitors to the cluster. 展荣臻（信泰） <zhanrzh_xt@teamsun.com.cn> 于2020年7月23日周四 下午8:23写道：

Hi,everyone Our production ceph cluster the version is hammer have 3 monitors and 300+ osds.Monitor daemon runs on host diffrent from osd daemon. openstack vm runs on rbd.Now we need to maintain monitor host so must shutdown monitor host a moment, one by one. But keep two monitor host online all the time. What is the impact of monitor down on vm? How to do reduce the impact? _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io