Red Hat SummitChapter 14. Create a CRUSH Hierarchy
You can run a Ceph cluster with a flat node-level hierarchy (default). This is NOT RECOMMENDED. We recommend adding named buckets of various types to your default CRUSH hierarchy. This will allow you to establish a larger-grained failure domain, usually consisting of racks, rows, rooms and data centers.
ceph osd crush add-bucket <bucket-name> <bucket-type>For example:
ceph osd crush add-bucket dc1 datacenter
ceph osd crush add-bucket room1 room
ceph osd crush add-bucket row1 row
ceph osd crush add-bucket rack1 rack
ceph osd crush add-bucket rack2 rack
ceph osd crush add-bucket rack3 rackThen, place the buckets into a hierarchy:
ceph osd crush move dc1 root=default
ceph osd crush move room1 datacenter=dc1
ceph osd crush move row1 room=room1
ceph osd crush move rack1 row=row1
ceph osd crush move node2 rack=rack1
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