crush rule multiple racks

# ceph osd crush rule dump multiple_racks
{
    "rule_id": 1,
    "rule_name": "multiple_racks",
    "ruleset": 1,
    "type": 1,
    "min_size": 1,
    "max_size": 10,
    "steps": [
        {
            "op": "take",
            "item": -1,
            "item_name": "default"
        },
        {
            "op": "chooseleaf_firstn",
            "num": 0,
            "type": "rack"
        },
        {
            "op": "emit"
        }
    ]
}

# ceph osd dump | grep 'replicated size'| grep volumes
pool 20 'volumes' replicated size 3 min_size 2 crush_ruleset 1 object_hash rjenkins pg_num 128 pgp_num 128 last_change 14278 flags hashpspool stripe_width 0

root@infra:~/tmp# ceph osd map volumes volume-3763df61-1095-4885-93da-cd87704b719d
osdmap e14282 pool 'volumes' (20) object 'volume-3763df61-1095-4885-93da-cd87704b719d' -> pg 20.40715e9f (20.1f) -> up ([30,418], p30) acting ([30,418,162], p30)