[ceph-users] New pool with SSD OSDs

Hello! We have a Ceph cluster with 30 HDD 4 TB in 6 hosts, only for RBD. Now, we're receiving other 6 servers with 6 SSD 2 TB each and we want to create a separate pool for RBD on SSD, and let unused and backup volumes stays in HDD. I have some questions: As I am only using "replicated_rule". ¿If I add an SSD OSD to the cluster, Ceph starts to migrate PGs to it? If so, to prevent this, first I have to create rule like     # ceph osd crush rule create-replicated pool-hdd default host hdd and then     #ceph osd pool set rbd crush_rule pool-hdd ? Or, if Ceph does not mix automatically hdd and ssd, I create the SSD OSD and then     # ceph osd crush rule create-replicated pool-ssd default host ssd     # ceph osd pool create pool-ssd 256 256 ssdpool ? And then migrate images from one to another pool as needed. Any thoughts are wellcome! Thanks in advanced for your time. Javier.-