CEPH RGW 设置 user default_placement为ssd-placement，优化100KB-200KB小文件性能，使用户创建的bucket对象放置到 SSD设备的Pool上。

sudo radosgw-admin metadata get user:tuanzi  > user.md.json

vi  user.md.json  #to add ssd-placement

{
    "key": "user:tuanzi",
    "ver": {
        "tag": "__gHSAD0K7rEZcQ2m3qT_RWk",
        "ver": 1
    },
    "mtime": "2017-02-27 06:48:17.488750Z",
    "data": {
        "user_id": "tuanzi",
        "display_name": "tuanzi",
        "email": "",
        "suspended": 0,
        "max_buckets": 1000,
        "auid": 0,
        "subusers": [],
        "keys": [
            {
                "user": "tuanzi",
                "access_key": "xxx",
                "secret_key": "xxx"
            }
        ],
        "swift_keys": [],
        "caps": [],
        "op_mask": "read, write, delete",
        "default_placement": "ssd-placement",
        "placement_tags": [],
        "bucket_quota": {
            "enabled": false,
            "max_size_kb": -1,
            "max_objects": -1
        },
        "user_quota": {
            "enabled": false,
            "max_size_kb": -1,
            "max_objects": -1
        },
        "temp_url_keys": [],
        "attrs": [
            {
                "key": "user.rgw.idtag",
                "val": ""
            },
            {
                "key": "user.rgw.manifest",
                "val": ""
            }
        ]
    }
}

sudo radosgw-admin metadata put user:tuanzi <user.md.json

$ radosgw-admin region get > region.conf.json
$ cat region.conf.json
{ "name": "default",
  "api_name": "",
  "is_master": "true",
  "endpoints": [],
  "master_zone": "",
  "zones": [
        { "name": "default",
          "endpoints": [],
          "log_meta": "false",
          "log_data": "false"}],
  "placement_targets": [
        { "name": "default-placement",
          "tags": []}],
  "default_placement": "default-placement"}


#<edit region config, add a new placement target>

{ "name": "default",
  "api_name": "",
  "is_master": "true",
  "endpoints": [],
  "master_zone": "",
  "zones": [
        { "name": "default",
          "endpoints": [],
          "log_meta": "false",
          "log_data": "false"}],
  "placement_targets": [
        { "name": "default-placement",
          "tags": []},
        { "name": "ssd-placement",
          "tags": []}],
  "default_placement": "default-placement"}

$ radosgw-admin region set < region.conf.json

sudo radosgw-admin zone get --rgw-zone=default >zone.json

#先创建在SSD设备上的default.rgw.buckets.data.ssd pool

vi zone.json # add ssd-placement 
{
    "id": "3d240698-79c4-4af0-abab-6b83b340a538",
    "name": "default",
    "domain_root": "default.rgw.data.root",
    "control_pool": "default.rgw.control",
    "gc_pool": "default.rgw.gc",
    "log_pool": "default.rgw.log",
    "intent_log_pool": "default.rgw.intent-log",
    "usage_log_pool": "default.rgw.usage",
    "user_keys_pool": "default.rgw.users.keys",
    "user_email_pool": "default.rgw.users.email",
    "user_swift_pool": "default.rgw.users.swift",
    "user_uid_pool": "default.rgw.users.uid",
    "system_key": {
        "access_key": "",
        "secret_key": ""
    },
    "placement_pools": [
        {
            "key": "default-placement",
            "val": {
                "index_pool": "default.rgw.buckets.index",
                "data_pool": "default.rgw.buckets.data",
                "data_extra_pool": "default.rgw.buckets.non-ec",
                "index_type": 0
            }
        },
        {
            "key": "ssd-placement",
            "val": {
                "index_pool": "default.rgw.buckets.index",
                "data_pool": "default.rgw.buckets.data.ssd",
                "data_extra_pool": "default.rgw.buckets.non-ec",
                "index_type": 0
            }
        }
    ],
    "metadata_heap": "default.rgw.meta",
    "realm_id": ""
}

sudo radosgw-admin zone set --rgw-zone=default --infile zone.json

设置以上规则后，再创建的bucket 放置规则是新的ssd-placement规则了。

http://cephnotes.ksperis.com/blog/2014/11/28/placement-pools-on-rados-gw

https://blog.widodh.nl/2013/11/changing-the-region-of-a-rgw-bucket/