Describe the issue: With RHCS 4.0 we have the ceph-bluestore-tool avail to assist with management of BlueStore devices including migration of the Bluestore block.db to a larger device if the customer initally deployed on a smaller device and was encountering spillover frequently. Discussed with RADOS engineering and they suggested we should be supporting this, if we are going to support this we need to document it. https://docs.ceph.com/docs/master/man/8/ceph-bluestore-tool/ Describe the task you were trying to accomplish: Document bluestore-tool Suggestions for improvement: Create section on tool and describe how to migrate block.db to larger device using 'bluefs-bdev-migrate' option. Document URL: https://docs.ceph.com/docs/master/man/8/ceph-bluestore-tool/ Product Version: RHCS 4.1