Chapter 7. Configuring the Object Storage service (swift)
You can configure the Object Storage service (swift) to use PersistentVolumes (PVs) on OpenShift nodes or disks on external data plane nodes.
When you use PVs on OpenShift nodes, this configuration is limited to a single PV per node. The Object Storage service requires multiple PVs. To maximize availability and data durability, you create these PVs on different nodes, and only use one PV per node.
You can use external data plane nodes for more flexibility in larger storage deployments, where you can use multiple disks per node to deploy a larger Object Storage cluster.
Prerequisites
-
You have the
oc
command line tool installed on your workstation. -
You are logged on to a workstation that has access to the RHOSO control plane as a user with
cluster-admin
privileges.
7.1. Deploying the Object Storage service on OpenShift nodes by using PersistentVolumes
You use at least two swiftProxy
replicas and three swiftStorage
replicas in a default Object Storage service (swift) deployment. You can increase these values to distribute storage across more nodes and disks.
The ringReplicas
value defines the number of object copies in the cluster. For example, if you set ringReplicas: 3
and swiftStorage/replicas: 5
, every object is stored on 3 different PersistentVolumes (PVs), and there are 5 PVs in total.
Procedure
Open your
OpenStackControlPlane
CR file,openstack_control_plane.yaml
, and add the following parameters to theswift
template:apiVersion: core.openstack.org/v1beta1 kind: OpenStackControlPlane metadata: name: openstack-control-plane namespace: openstack spec: ... swift: enabled: true template: swiftProxy: replicas: 2 swiftRing: ringReplicas: 3 swiftStorage: replicas: 3 storageClass: <swift-storage> storageRequest: 100Gi ...
-
Increase the
swiftProxy/replicas:
value to distribute proxy instances across more nodes. -
Replace the
ringReplicas:
value to define the number of object copies you want in your cluster. -
Increase the
swiftStorage/replicas:
value to define the number of PVs in your cluster. -
Replace
<swift-storage>
with the name of the storage class you want the Object Storage service to use.
-
Increase the
Update the control plane:
$ oc apply -f openstack_control_plane.yaml -n openstack
Wait until RHOCP creates the resources related to the
OpenStackControlPlane
CR. Run the following command to check the status:$ oc get openstackcontrolplane -n openstack
The
OpenStackControlPlane
resources are created when the status is "Setup complete".TipAppend the
-w
option to the end of theget
command to track deployment progress.
7.2. Object Storage rings
The Object Storage service (swift) uses a data structure called the ring to distribute partition space across the cluster. This partition space is core to the data durability engine in the Object Storage service. With rings, the Object Storage service can quickly and easily synchronize each partition across the cluster.
Rings contain information about Object Storage partitions and how partitions are distributed among the different nodes and disks in your Red Hat OpenStack Services on OpenShift (RHOSO) deployment. When any Object Storage component interacts with data, a quick lookup is performed locally in the ring to determine the possible partitions for each object.
The Object Storage service has three rings to store the following types of data:
- Account information
- Containers, to facilitate organizing objects under an account
- Object replicas
7.3. Ring partition power
The ring power determines the partition to which a resource, such as an account, container, or object, is mapped. The partition is included in the path under which the resource is stored in a back-end file system. Therefore, changing the partition power requires relocating resources to new paths in the back-end file systems.
In a heavily populated cluster, a relocation process is time consuming. To avoid downtime, relocate resources while the cluster is still operating. You must do this without temporarily losing access to data or compromising the performance of processes, such as replication and auditing. For assistance with increasing ring partition power, contact Red Hat Support.
When you use separate nodes for the Object Storage service (swift), use a higher partition power value.
The Object Storage service distributes data across disks and nodes using modified hash rings. There are three rings by default: one for accounts, one for containers, and one for objects. Each ring uses a fixed parameter called partition power. This parameter sets the maximum number of partitions that can be created.
7.4. Increasing ring partition power
You can only change the partition power parameter for new containers and their objects, so you must set this value before initial deployment.
The default partition power value is 10
. Refer to the following table to select an appropriate partition power if you use three replicas:
Partition Power | Maximum number of disks |
10 | ~ 35 |
11 | ~ 75 |
12 | ~ 150 |
13 | ~ 250 |
14 | ~ 500 |
Setting an excessively high partition power value (for example, 14
for only 40 disks) negatively impacts replication times.
Procedure
Open your
OpenStackControlPlane
CR file,openstack_control_plane.yaml
, and change the value forpartPower
under theswiftRing
parameter in theswift
template:apiVersion: core.openstack.org/v1beta1 kind: OpenStackControlPlane metadata: name: openstack-control-plane namespace: openstack spec: ... swift: enabled: true template: swiftProxy: replicas: 2 swiftRing: partPower: 12 ringReplicas: 3 ...
Replace
<12>
with the value you want to set for partition power.TipYou can also configure an additional object server ring for new containers. This is useful if you want to add more disks to an Object Storage service deployment that initially uses a low partition power.