在调试Ceph的librbd客户端时候，可以临时打开librbd日志，配置ceph.conf如下：
[root@controller ~]# cat /etc/ceph/ceph.conf
[global]
fsid = 494b1787-d94b-457e-917c-6cae1a5f6656
mon_initial_members = ceph1, ceph2, ceph3
mon_host = 10.20.30.11,10.20.30.12,10.20.30.13
auth_cluster_required = cephx
auth_service_required = cephx
auth_client_required = cephx
debug_client = 30
debug_objecter = 30
debug_librbd = 30
[client]
log file = /var/log/ceph/ceph.log
其中ceph.log文件需要有可写权限：
[root@controller ~]# ll /var/log/ceph/ceph.log
-rwxrwxrwx 1 root root 318492202 Nov 9 11:17 /var/log/ceph/ceph.log
然后，客户端开启的虚机，如果挂载和卸载rbd类型的云硬盘则会有日志输出了。