Pool Placement ¶

Placement Targets ¶

New in version Jewel.

Placement targets control which Pools are associated with a particular bucket. A bucket’s placement target is selected on creation, and cannot be modified. The radosgw-admin bucket stats command will display its placement_rule.

The zonegroup configuration contains a list of placement targets with an initial target named default-placement. The zone configuration then maps each zonegroup placement target name onto its local storage. This zone placement information includes the index_pool name for the bucket index, the data_extra_pool name for metadata about incomplete multipart uploads, and a data_pool name for object data.

Zonegroup/Zone Configuration ¶

Placement configuration is performed with radosgw-admin commands on the zonegroups and zones.

The zonegroup placement configuration can be queried with:

$ radosgw-admin zonegroup get
{
    "id": "ab01123f-e0df-4f29-9d71-b44888d67cd5",
    "name": "default",
    "api_name": "default",
    ...
    "placement_targets": [
        {
            "name": "default-placement",
            "tags": [],
        }
    ],
    "default_placement": "default-placement",
    ...
}

The zone placement configuration can be queried with:

$ radosgw-admin zone get
{
    "id": "557cdcee-3aae-4e9e-85c7-2f86f5eddb1f",
    "name": "default",
    "domain_root": "default.rgw.meta:root",
    ...
    "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
            }
        }
    ],
    ...
}

Note

If you have not done any previous Multisite Configuration, a default zone and zonegroup are created for you, and changes to the zone/zonegroup will not take effect until the Ceph Object Gateways are restarted. If you have created a realm for multisite, the zone/zonegroup changes will take effect once the changes are committed with radosgw-admin period update --commit.

Adding a Placement Target ¶

To create a new placement target named temporary, start by adding it to the zonegroup:

$ radosgw-admin zonegroup placement add \
      --rgw-zonegroup default \
      --placement-id temporary

Then provide the zone placement info for that target:

$ radosgw-admin zone placement add \
      --rgw-zone default \
      --placement-id temporary \
      --data-pool default.rgw.temporary.data \
      --index-pool default.rgw.temporary.index \
      --data-extra-pool default.rgw.temporary.non-ec \
      --compression lz4

Customizing Placement ¶

Default Placement ¶

By default, new buckets will use the zonegroup’s default_placement target. This zonegroup setting can be changed with:

$ radosgw-admin zonegroup placement default \
      --rgw-zonegroup default \
      --placement-id new-placement

User Placement ¶

A Ceph Object Gateway user can override the zonegroup’s default placement target by setting a non-empty default_placement field in the user info.

$ radosgw-admin user info --uid testid
{
    ...
    "default_placement": "",
    "placement_tags": [],
    ...
}

If a zonegroup’s placement target contains any tags, users will be unable to create buckets with that placement target unless their user info contains at least one matching tag in its placement_tags field. This can be useful to restrict access to certain types of storage.

The radosgw-admin command cannot modify these fields directly, so the json format must be edited manually:

$ radosgw-admin metadata get user:<user-id> > user.json
$ vi user.json
$ radosgw-admin metadata put user:<user-id> < user.json

S3 Bucket Placement ¶

When creating a bucket with the S3 protocol, a placement target can be provided as part of the LocationConstraint to override the default placement targets from the user and zonegroup.

Normally, the LocationConstraint must match the zonegroup’s api_name:

<LocationConstraint>default</LocationConstraint>

A custom placement target can be added to the api_name following a colon:

<LocationConstraint>default:new-placement</LocationConstraint>

Swift Bucket Placement ¶

When creating a bucket with the Swift protocol, a placement target can be provided in the HTTP header X-Storage-Policy:

X-Storage-Policy: new-placement