Ce contenu n'est pas disponible dans la langue sélectionnée.
Chapter 8. Post-installation storage configuration
After installing OpenShift Container Platform, you can further expand and customize your cluster to your requirements, including storage configuration.
8.1. Dynamic provisioning
8.1.1. About dynamic provisioning
The StorageClass
resource object describes and classifies storage that can be requested, as well as provides a means for passing parameters for dynamically provisioned storage on demand. StorageClass
objects can also serve as a management mechanism for controlling different levels of storage and access to the storage. Cluster Administrators (cluster-admin
) or Storage Administrators (storage-admin
) define and create the StorageClass
objects that users can request without needing any detailed knowledge about the underlying storage volume sources.
The OpenShift Container Platform persistent volume framework enables this functionality and allows administrators to provision a cluster with persistent storage. The framework also gives users a way to request those resources without having any knowledge of the underlying infrastructure.
Many storage types are available for use as persistent volumes in OpenShift Container Platform. While all of them can be statically provisioned by an administrator, some types of storage are created dynamically using the built-in provider and plugin APIs.
8.1.2. Available dynamic provisioning plugins
OpenShift Container Platform provides the following provisioner plugins, which have generic implementations for dynamic provisioning that use the cluster’s configured provider’s API to create new storage resources:
Storage type | Provisioner plugin name | Notes |
---|---|---|
Red Hat OpenStack Platform (RHOSP) Cinder |
| |
RHOSP Manila Container Storage Interface (CSI) |
| Once installed, the OpenStack Manila CSI Driver Operator and ManilaDriver automatically create the required storage classes for all available Manila share types needed for dynamic provisioning. |
AWS Elastic Block Store (EBS) |
|
For dynamic provisioning when using multiple clusters in different zones, tag each node with |
Azure Disk |
| |
Azure File |
|
The |
GCE Persistent Disk (gcePD) |
| In multi-zone configurations, it is advisable to run one OpenShift Container Platform cluster per GCE project to avoid PVs from being created in zones where no node in the current cluster exists. |
|
Any chosen provisioner plugin also requires configuration for the relevant cloud, host, or third-party provider as per the relevant documentation.
8.2. Defining a storage class
StorageClass
objects are currently a globally scoped object and must be created by cluster-admin
or storage-admin
users.
The Cluster Storage Operator might install a default storage class depending on the platform in use. This storage class is owned and controlled by the operator. It cannot be deleted or modified beyond defining annotations and labels. If different behavior is desired, you must define a custom storage class.
The following sections describe the basic definition for a StorageClass
object and specific examples for each of the supported plugin types.
8.2.1. Basic StorageClass object definition
The following resource shows the parameters and default values that you use to configure a storage class. This example uses the AWS ElasticBlockStore (EBS) object definition.
Sample StorageClass
definition
kind: StorageClass 1 apiVersion: storage.k8s.io/v1 2 metadata: name: <storage-class-name> 3 annotations: 4 storageclass.kubernetes.io/is-default-class: 'true' ... provisioner: kubernetes.io/aws-ebs 5 parameters: 6 type: gp2 ...
- 1
- (required) The API object type.
- 2
- (required) The current apiVersion.
- 3
- (required) The name of the storage class.
- 4
- (optional) Annotations for the storage class.
- 5
- (required) The type of provisioner associated with this storage class.
- 6
- (optional) The parameters required for the specific provisioner, this will change from plugin to plugin.
8.2.2. Storage class annotations
To set a storage class as the cluster-wide default, add the following annotation to your storage class metadata:
storageclass.kubernetes.io/is-default-class: "true"
For example:
apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: annotations: storageclass.kubernetes.io/is-default-class: "true" ...
This enables any persistent volume claim (PVC) that does not specify a specific storage class to automatically be provisioned through the default storage class. However, your cluster can have more than one storage class, but only one of them can be the default storage class.
The beta annotation storageclass.beta.kubernetes.io/is-default-class
is still working; however, it will be removed in a future release.
To set a storage class description, add the following annotation to your storage class metadata:
kubernetes.io/description: My Storage Class Description
For example:
apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: annotations: kubernetes.io/description: My Storage Class Description ...
8.2.3. RHOSP Cinder object definition
cinder-storageclass.yaml
kind: StorageClass apiVersion: storage.k8s.io/v1 metadata: name: <storage-class-name> 1 provisioner: kubernetes.io/cinder parameters: type: fast 2 availability: nova 3 fsType: ext4 4
- 1
- Name of the storage class. The persistent volume claim uses this storage class for provisioning the associated persistent volumes.
- 2
- Volume type created in Cinder. Default is empty.
- 3
- Availability Zone. If not specified, volumes are generally round-robined across all active zones where the OpenShift Container Platform cluster has a node.
- 4
- File system that is created on dynamically provisioned volumes. This value is copied to the
fsType
field of dynamically provisioned persistent volumes and the file system is created when the volume is mounted for the first time. The default value isext4
.
8.2.4. AWS Elastic Block Store (EBS) object definition
aws-ebs-storageclass.yaml
kind: StorageClass apiVersion: storage.k8s.io/v1 metadata: name: <storage-class-name> 1 provisioner: kubernetes.io/aws-ebs parameters: type: io1 2 iopsPerGB: "10" 3 encrypted: "true" 4 kmsKeyId: keyvalue 5 fsType: ext4 6
- 1
- (required) Name of the storage class. The persistent volume claim uses this storage class for provisioning the associated persistent volumes.
- 2
- (required) Select from
io1
,gp2
,sc1
,st1
. The default isgp2
. See the AWS documentation for valid Amazon Resource Name (ARN) values. - 3
- Optional: Only for io1 volumes. I/O operations per second per GiB. The AWS volume plugin multiplies this with the size of the requested volume to compute IOPS of the volume. The value cap is 20,000 IOPS, which is the maximum supported by AWS. See the AWS documentation for further details.
- 4
- Optional: Denotes whether to encrypt the EBS volume. Valid values are
true
orfalse
. - 5
- Optional: The full ARN of the key to use when encrypting the volume. If none is supplied, but
encypted
is set totrue
, then AWS generates a key. See the AWS documentation for a valid ARN value. - 6
- Optional: File system that is created on dynamically provisioned volumes. This value is copied to the
fsType
field of dynamically provisioned persistent volumes and the file system is created when the volume is mounted for the first time. The default value isext4
.
8.2.5. Azure Disk object definition
azure-advanced-disk-storageclass.yaml
apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: name: <storage-class-name> 1 provisioner: kubernetes.io/azure-disk volumeBindingMode: WaitForFirstConsumer 2 allowVolumeExpansion: true parameters: kind: Managed 3 storageaccounttype: Premium_LRS 4 reclaimPolicy: Delete
- 1
- Name of the storage class. The persistent volume claim uses this storage class for provisioning the associated persistent volumes.
- 2
- Using
WaitForFirstConsumer
is strongly recommended. This provisions the volume while allowing enough storage to schedule the pod on a free worker node from an available zone. - 3
- Possible values are
Shared
(default),Managed
, andDedicated
.ImportantRed Hat only supports the use of
kind: Managed
in the storage class.With
Shared
andDedicated
, Azure creates unmanaged disks, while OpenShift Container Platform creates a managed disk for machine OS (root) disks. But because Azure Disk does not allow the use of both managed and unmanaged disks on a node, unmanaged disks created withShared
orDedicated
cannot be attached to OpenShift Container Platform nodes. - 4
- Azure storage account SKU tier. Default is empty. Note that Premium VMs can attach both
Standard_LRS
andPremium_LRS
disks, Standard VMs can only attachStandard_LRS
disks, Managed VMs can only attach managed disks, and unmanaged VMs can only attach unmanaged disks.-
If
kind
is set toShared
, Azure creates all unmanaged disks in a few shared storage accounts in the same resource group as the cluster. -
If
kind
is set toManaged
, Azure creates new managed disks. If
kind
is set toDedicated
and astorageAccount
is specified, Azure uses the specified storage account for the new unmanaged disk in the same resource group as the cluster. For this to work:- The specified storage account must be in the same region.
- Azure Cloud Provider must have write access to the storage account.
-
If
kind
is set toDedicated
and astorageAccount
is not specified, Azure creates a new dedicated storage account for the new unmanaged disk in the same resource group as the cluster.
-
If
8.2.6. Azure File object definition
The Azure File storage class uses secrets to store the Azure storage account name and the storage account key that are required to create an Azure Files share. These permissions are created as part of the following procedure.
Procedure
Define a
ClusterRole
object that allows access to create and view secrets:apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: # name: system:azure-cloud-provider name: <persistent-volume-binder-role> 1 rules: - apiGroups: [''] resources: ['secrets'] verbs: ['get','create']
- 1
- The name of the cluster role to view and create secrets.
Add the cluster role to the service account:
$ oc adm policy add-cluster-role-to-user <persistent-volume-binder-role> system:serviceaccount:kube-system:persistent-volume-binder
Create the Azure File
StorageClass
object:kind: StorageClass apiVersion: storage.k8s.io/v1 metadata: name: <azure-file> 1 provisioner: kubernetes.io/azure-file parameters: location: eastus 2 skuName: Standard_LRS 3 storageAccount: <storage-account> 4 reclaimPolicy: Delete volumeBindingMode: Immediate
- 1
- Name of the storage class. The persistent volume claim uses this storage class for provisioning the associated persistent volumes.
- 2
- Location of the Azure storage account, such as
eastus
. Default is empty, meaning that a new Azure storage account will be created in the OpenShift Container Platform cluster’s location. - 3
- SKU tier of the Azure storage account, such as
Standard_LRS
. Default is empty, meaning that a new Azure storage account will be created with theStandard_LRS
SKU. - 4
- Name of the Azure storage account. If a storage account is provided, then
skuName
andlocation
are ignored. If no storage account is provided, then the storage class searches for any storage account that is associated with the resource group for any accounts that match the definedskuName
andlocation
.
8.2.6.1. Considerations when using Azure File
The following file system features are not supported by the default Azure File storage class:
- Symlinks
- Hard links
- Extended attributes
- Sparse files
- Named pipes
Additionally, the owner user identifier (UID) of the Azure File mounted directory is different from the process UID of the container. The uid
mount option can be specified in the StorageClass
object to define a specific user identifier to use for the mounted directory.
The following StorageClass
object demonstrates modifying the user and group identifier, along with enabling symlinks for the mounted directory.
kind: StorageClass apiVersion: storage.k8s.io/v1 metadata: name: azure-file mountOptions: - uid=1500 1 - gid=1500 2 - mfsymlinks 3 provisioner: kubernetes.io/azure-file parameters: location: eastus skuName: Standard_LRS reclaimPolicy: Delete volumeBindingMode: Immediate
8.2.7. GCE PersistentDisk (gcePD) object definition
gce-pd-storageclass.yaml
apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: name: <storage-class-name> 1 provisioner: kubernetes.io/gce-pd parameters: type: pd-standard 2 replication-type: none volumeBindingMode: WaitForFirstConsumer allowVolumeExpansion: true reclaimPolicy: Delete
8.2.8. VMware vSphere object definition
vsphere-storageclass.yaml
kind: StorageClass apiVersion: storage.k8s.io/v1 metadata: name: <storage-class-name> 1 provisioner: kubernetes.io/vsphere-volume 2 parameters: diskformat: thin 3
- 1
- Name of the storage class. The persistent volume claim uses this storage class for provisioning the associated persistent volumes.
- 2
- For more information about using VMware vSphere with OpenShift Container Platform, see the VMware vSphere documentation.
- 3
diskformat
:thin
,zeroedthick
andeagerzeroedthick
are all valid disk formats. See vSphere docs for additional details regarding the disk format types. The default value isthin
.
8.2.9. Red Hat Virtualization (RHV) object definition
OpenShift Container Platform creates a default object of type StorageClass
named ovirt-csi-sc
which is used for creating dynamically provisioned persistent volumes.
To create additional storage classes for different configurations, create and save a file with the StorageClass
object described by the following sample YAML:
ovirt-storageclass.yaml
apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: name: <storage_class_name> 1 annotations: storageclass.kubernetes.io/is-default-class: "<boolean>" 2 provisioner: csi.ovirt.org allowVolumeExpansion: <boolean> 3 reclaimPolicy: Delete 4 volumeBindingMode: Immediate 5 parameters: storageDomainName: <rhv-storage-domain-name> 6 thinProvisioning: "<boolean>" 7 csi.storage.k8s.io/fstype: <file_system_type> 8
- 1
- Name of the storage class.
- 2
- Set to
false
if the storage class is the default storage class in the cluster. If set totrue
, the existing default storage class must be edited and set tofalse
. - 3
true
enables dynamic volume expansion,false
prevents it.true
is recommended.- 4
- Dynamically provisioned persistent volumes of this storage class are created with this reclaim policy. This default policy is
Delete
. - 5
- Indicates how to provision and bind
PersistentVolumeClaims
. When not set,VolumeBindingImmediate
is used. This field is only applied by servers that enable theVolumeScheduling
feature. - 6
- The RHV storage domain name to use.
- 7
- If
true
, the disk is thin provisioned. Iffalse
, the disk is preallocated. Thin provisioning is recommended. - 8
- Optional: File system type to be created. Possible values:
ext4
(default) orxfs
.
8.3. Changing the default storage class
Use the following process to change the default storage class. For example you have two defined storage classes, gp2
and standard
, and you want to change the default storage class from gp2
to standard
.
List the storage class:
$ oc get storageclass
Example output
NAME TYPE gp2 (default) kubernetes.io/aws-ebs 1 standard kubernetes.io/aws-ebs
- 1
(default)
denotes the default storage class.
Change the value of the
storageclass.kubernetes.io/is-default-class
annotation tofalse
for the default storage class:$ oc patch storageclass gp2 -p '{"metadata": {"annotations": {"storageclass.kubernetes.io/is-default-class": "false"}}}'
Make another storage class the default by setting the
storageclass.kubernetes.io/is-default-class
annotation totrue
:$ oc patch storageclass standard -p '{"metadata": {"annotations": {"storageclass.kubernetes.io/is-default-class": "true"}}}'
Verify the changes:
$ oc get storageclass
Example output
NAME TYPE gp2 kubernetes.io/aws-ebs standard (default) kubernetes.io/aws-ebs
8.4. Optimizing storage
Optimizing storage helps to minimize storage use across all resources. By optimizing storage, administrators help ensure that existing storage resources are working in an efficient manner.
8.5. Available persistent storage options
Understand your persistent storage options so that you can optimize your OpenShift Container Platform environment.
Storage type | Description | Examples |
---|---|---|
Block |
| AWS EBS and VMware vSphere support dynamic persistent volume (PV) provisioning natively in OpenShift Container Platform. |
File |
| RHEL NFS, NetApp NFS [1], and Vendor NFS |
Object |
| AWS S3 |
- NetApp NFS supports dynamic PV provisioning when using the Trident plugin.
Currently, CNS is not supported in OpenShift Container Platform 4.10.
8.6. Recommended configurable storage technology
The following table summarizes the recommended and configurable storage technologies for the given OpenShift Container Platform cluster application.
Storage type | ROX1 | RWX2 | Registry | Scaled registry | Metrics3 | Logging | Apps |
---|---|---|---|---|---|---|---|
1
2 3 Prometheus is the underlying technology used for metrics. 4 This does not apply to physical disk, VM physical disk, VMDK, loopback over NFS, AWS EBS, and Azure Disk.
5 For metrics, using file storage with the 6 For logging, using any shared storage would be an anti-pattern. One volume per elasticsearch is required. 7 Object storage is not consumed through OpenShift Container Platform’s PVs or PVCs. Apps must integrate with the object storage REST API. | |||||||
Block | Yes4 | No | Configurable | Not configurable | Recommended | Recommended | Recommended |
File | Yes4 | Yes | Configurable | Configurable | Configurable5 | Configurable6 | Recommended |
Object | Yes | Yes | Recommended | Recommended | Not configurable | Not configurable | Not configurable7 |
A scaled registry is an OpenShift image registry where two or more pod replicas are running.
8.6.1. Specific application storage recommendations
Testing shows issues with using the NFS server on Red Hat Enterprise Linux (RHEL) as storage backend for core services. This includes the OpenShift Container Registry and Quay, Prometheus for monitoring storage, and Elasticsearch for logging storage. Therefore, using RHEL NFS to back PVs used by core services is not recommended.
Other NFS implementations on the marketplace might not have these issues. Contact the individual NFS implementation vendor for more information on any testing that was possibly completed against these OpenShift Container Platform core components.
8.6.1.1. Registry
In a non-scaled/high-availability (HA) OpenShift image registry cluster deployment:
- The storage technology does not have to support RWX access mode.
- The storage technology must ensure read-after-write consistency.
- The preferred storage technology is object storage followed by block storage.
- File storage is not recommended for OpenShift image registry cluster deployment with production workloads.
8.6.1.2. Scaled registry
In a scaled/HA OpenShift image registry cluster deployment:
- The storage technology must support RWX access mode.
- The storage technology must ensure read-after-write consistency.
- The preferred storage technology is object storage.
- Red Hat OpenShift Data Foundation (ODF), Amazon Simple Storage Service (Amazon S3), Google Cloud Storage (GCS), Microsoft Azure Blob Storage, and OpenStack Swift are supported.
- Object storage should be S3 or Swift compliant.
- For non-cloud platforms, such as vSphere and bare metal installations, the only configurable technology is file storage.
- Block storage is not configurable.
8.6.1.3. Metrics
In an OpenShift Container Platform hosted metrics cluster deployment:
- The preferred storage technology is block storage.
- Object storage is not configurable.
It is not recommended to use file storage for a hosted metrics cluster deployment with production workloads.
8.6.1.4. Logging
In an OpenShift Container Platform hosted logging cluster deployment:
- The preferred storage technology is block storage.
- Object storage is not configurable.
8.6.1.5. Applications
Application use cases vary from application to application, as described in the following examples:
- Storage technologies that support dynamic PV provisioning have low mount time latencies, and are not tied to nodes to support a healthy cluster.
- Application developers are responsible for knowing and understanding the storage requirements for their application, and how it works with the provided storage to ensure that issues do not occur when an application scales or interacts with the storage layer.
8.6.2. Other specific application storage recommendations
It is not recommended to use RAID configurations on Write
intensive workloads, such as etcd
. If you are running etcd
with a RAID configuration, you might be at risk of encountering performance issues with your workloads.
- Red Hat OpenStack Platform (RHOSP) Cinder: RHOSP Cinder tends to be adept in ROX access mode use cases.
- Databases: Databases (RDBMSs, NoSQL DBs, etc.) tend to perform best with dedicated block storage.
- The etcd database must have enough storage and adequate performance capacity to enable a large cluster. Information about monitoring and benchmarking tools to establish ample storage and a high-performance environment is described in Recommended etcd practices.
Additional resources
8.7. Deploy Red Hat OpenShift Data Foundation
Red Hat OpenShift Data Foundation is a provider of agnostic persistent storage for OpenShift Container Platform supporting file, block, and object storage, either in-house or in hybrid clouds. As a Red Hat storage solution, Red Hat OpenShift Data Foundation is completely integrated with OpenShift Container Platform for deployment, management, and monitoring.
If you are looking for Red Hat OpenShift Data Foundation information about… | See the following Red Hat OpenShift Data Foundation documentation: |
---|---|
What’s new, known issues, notable bug fixes, and Technology Previews | |
Supported workloads, layouts, hardware and software requirements, sizing and scaling recommendations | |
Instructions on deploying OpenShift Data Foundation to use an external Red Hat Ceph Storage cluster | |
Instructions on deploying OpenShift Data Foundation to local storage on bare metal infrastructure | Deploying OpenShift Data Foundation 4.9 using bare metal infrastructure |
Instructions on deploying OpenShift Data Foundation on Red Hat OpenShift Container Platform VMware vSphere clusters | |
Instructions on deploying OpenShift Data Foundation using Amazon Web Services for local or cloud storage | Deploying OpenShift Data Foundation 4.9 using Amazon Web Services |
Instructions on deploying and managing OpenShift Data Foundation on existing Red Hat OpenShift Container Platform Google Cloud clusters | Deploying and managing OpenShift Data Foundation 4.9 using Google Cloud |
Instructions on deploying and managing OpenShift Data Foundation on existing Red Hat OpenShift Container Platform Azure clusters | Deploying and managing OpenShift Data Foundation 4.9 using Microsoft Azure |
Instructions on deploying OpenShift Data Foundation to use local storage on IBM Power infrastructure | |
Instructions on deploying OpenShift Data Foundation to use local storage on IBM Z infrastructure | |
Allocating storage to core services and hosted applications in Red Hat OpenShift Data Foundation, including snapshot and clone | |
Managing storage resources across a hybrid cloud or multicloud environment using the Multicloud Object Gateway (NooBaa) | |
Safely replacing storage devices for Red Hat OpenShift Data Foundation | |
Safely replacing a node in a Red Hat OpenShift Data Foundation cluster | |
Scaling operations in Red Hat OpenShift Data Foundation | |
Monitoring a Red Hat OpenShift Data Foundation 4.9 cluster | |
Resolve issues encountered during operations | |
Migrating your OpenShift Container Platform cluster from version 3 to version 4 |