Hi Alwin and thanks for your advice concerning the principle of a baseline comparison. In fact, I don't know exactly the performance I can expect but I have made another fio benchs (I have read some docs about fio) and I have the feeling that my new benchs are not really good as regard my underlying hardware (see below). So, I have tested a simple SSD Intel S3520 (a "OSD" disk) as you said with this fio command (the SSD was formated in EXT4): Code: fio --bs=4k --size=4G --numjobs=3 --time_based --runtime=40 --group_reporting --name myjob \ --rw=randwrite --ioengine=libaio --iodepth=8 --direct=1 --fsync=1 and I obtain approximatively 6261 iops. After that, I have tested exactly the same fio bench in a Debian Stretch VM (which uses the Ceph storage of course, with a VirtIO disk and 512MB for the RAM) and I obtain approximatively 362 iops. 1. It seems to me not very good as regard my hardware configuration (I have 24 SSD ODS!). Am I wrong? 2. Which another tests/benchs can I try? Just for memory, here is my configuration and the complete output of the fio benchs in the attachment file promox-5.2-ceph-luminous-conf.txt. Thx in advance for your help.