Pool Placement and Storage Classes¶
Contents
归置目标¶
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 each storage class.
Storage Classes¶
New in version Nautilus.
Storage classes are used to customize the placement of object data. S3 Bucket Lifecycle rules can automate the transition of objects between storage classes.
Storage classes are defined in terms of placement targets. Each zonegroup
placement target lists its available storage classes with an initial class
named STANDARD
. The zone configuration is responsible for providing a
data_pool
pool name for each of the zonegroup’s storage classes.
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": [],
"storage_classes": [
"STANDARD"
]
}
],
"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",
"storage_classes": {
"STANDARD": {
"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
.
新增一个归置目标¶
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
Adding a Storage Class¶
To add a new storage class named COLD
to the default-placement
target,
start by adding it to the zonegroup:
$ radosgw-admin zonegroup placement add \
--rgw-zonegroup default \
--placement-id default-placement \
--storage-class COLD
Then provide the zone placement info for that storage class:
$ radosgw-admin zone placement add \
--rgw-zone default \
--placement-id default-placement \
--storage-class COLD \
--data-pool default.rgw.cold.data \
--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.
Similarly, the default_storage_class
can override the STANDARD
storage class applied to objects by default.
$ radosgw-admin user info --uid testid
{
...
"default_placement": "",
"default_storage_class": "",
"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
Using Storage Classes¶
All placement targets have a STANDARD
storage class which is applied to
new objects by default. The user can override this default with its
default_storage_class
.
To create an object in a non-default storage class, provide that storage class
name in an HTTP header with the request. The S3 protocol uses the
X-Amz-Storage-Class
header, while the Swift protocol uses the
X-Object-Storage-Class
header.
S3 Object Lifecycle Management can then be used to move object data between
storage classes using Transition
actions.