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[replication] Added Unity replication section (#302)
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| --- | ||
| title: Unity | ||
| linktitle: Unity | ||
| weight: 7 | ||
| description: > | ||
| Enabling Replication feature for CSI Unity | ||
| --- | ||
| ## Enabling Replication in CSI Unity | ||
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| Container Storage Modules (CSM) Replication sidecar is a helper container that is installed alongside a CSI driver to facilitate replication functionality. Such CSI drivers must implement `dell-csi-extensions` calls. | ||
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| CSI driver for Dell Unity supports necessary extension calls from `dell-csi-extensions`. To be able to provision replicated volumes you would need to do the steps described in these sections. | ||
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| ### Before Installation | ||
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| #### On Storage Array | ||
| Be sure to configure replication between multiple Unity instances using instructions provided by | ||
| Unity storage. | ||
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| #### In Kubernetes | ||
| Ensure you installed CRDs and replication controller in your clusters. | ||
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| To verify you have everything in order you can execute these commands: | ||
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| * Check controller pods | ||
| ```shell | ||
| kubectl get pods -n dell-replication-controller | ||
| ``` | ||
| Pods should be `READY` and `RUNNING` | ||
| * Check that controller config map is properly populated | ||
| ```shell | ||
| kubectl get cm -n dell-replication-controller dell-replication-controller-config -o yaml | ||
| ``` | ||
| `data` field should be properly populated with cluster-id of your choosing and, if using multi-cluster | ||
| installation, your `targets:` parameter should be populated by a list of target clusters IDs. | ||
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| If you don't have something installed or something is out-of-place, please refer to installation instructions in [installation-repctl](../install-repctl) or [installation](../installation). | ||
| ### Installing Driver With Replication Module | ||
| To install the driver with replication enabled, you need to ensure you have set | ||
| helm parameter `controller.replication.enabled` in your copy of example `values.yaml` file | ||
| (usually called `my-unity-settings.yaml`, `myvalues.yaml` etc.). | ||
| Here is an example of what that would look like: | ||
| ```yaml | ||
| ... | ||
| # controller: configure controller specific parameters | ||
| controller: | ||
| ... | ||
| # replication: allows to configure replication | ||
| replication: | ||
| enabled: true | ||
| image: dellemc/dell-csi-replicator:v1.2.0 | ||
| replicationContextPrefix: "unity" | ||
| replicationPrefix: "replication.storage.dell.com" | ||
| ... | ||
| ``` | ||
| You can leave other parameters like `image`, `replicationContextPrefix`, and `replicationPrefix` as they are. | ||
| After enabling the replication module, you can continue to install the CSI driver for Unity following the usual installation procedure. Just ensure you've added the necessary array connection information to secret. | ||
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| > **_NOTE:_** you need to install your driver on ALL clusters where you want to use replication. Both arrays must be accessible from each cluster. | ||
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| ### Creating Storage Classes | ||
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| To provision replicated volumes, you need to create adequately configured storage classes on both the source and target clusters. | ||
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| A pair of storage classes on the source, and target clusters would be essentially `mirrored` copies of one another. | ||
| You can create them manually or with the help of `repctl`. | ||
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| #### Manual Storage Class Creation | ||
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| You can find a sample replication enabled storage class in the driver repository [here](https://github.com/dell/csi-unity/blob/main/samples/storageclass/unity-replication.yaml). | ||
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| It will look like this: | ||
| ```yaml | ||
| apiVersion: storage.k8s.io/v1 | ||
| kind: StorageClass | ||
| metadata: | ||
| name: unity-replication | ||
| provisioner: csi-unity.dellemc.com | ||
| reclaimPolicy: Delete | ||
| volumeBindingMode: Immediate | ||
| parameters: | ||
| replication.storage.dell.com/isReplicationEnabled: "true" | ||
| replication.storage.dell.com/remoteStorageClassName: "unity-replication" | ||
| replication.storage.dell.com/remoteClusterID: "target" | ||
| replication.storage.dell.com/remoteSystem: "APM000000002" | ||
| replication.storage.dell.com/rpo: "5" | ||
| replication.storage.dell.com/ignoreNamespaces: "false" | ||
| replication.storage.dell.com/volumeGroupPrefix: "csi" | ||
| replication.storage.dell.com/remoteStoragePool: pool_002 | ||
| replication.storage.dell.com/remoteNasServer: nas_124 | ||
| arrayId: "APM000000001" | ||
| protocol: "NFS" | ||
| storagePool: pool_001 | ||
| nasServer: nas_123 | ||
| ``` | ||
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| Let's go through each parameter and what it means: | ||
| * `replication.storage.dell.com/isReplicationEnabled` if set to `true`, will mark this storage class as replication enabled, | ||
| just leave it as `true`. | ||
| * `replication.storage.dell.com/remoteStorageClassName` points to the name of the remote storage class. If you are using replication with the multi-cluster configuration you can make it the same as the current storage class name. | ||
| * `replication.storage.dell.com/remoteClusterID` represents the ID of a remote cluster. It is the same id you put in the replication controller config map. | ||
| * `replication.storage.dell.com/remoteSystem` is the name of the remote system that should match whatever `clusterName` you called it in `unity-creds` secret. | ||
| * `replication.storage.dell.com/rpo` is an acceptable amount of data, which is measured in units of time, that may be lost due to a failure. | ||
| * `replication.storage.dell.com/ignoreNamespaces`, if set to `true` Unity driver, it will ignore in what namespace volumes are created and put every volume created using this storage class into a single volume group. | ||
| * `replication.storage.dell.com/volumeGroupPrefix` represents what string would be appended to the volume group name to differentiate them. | ||
| * `arrayId` is a unique identifier of the storage array you specified in array connection secret. | ||
| * `nasServer` id of the Nas server of local array to which the allocated volume will belong. | ||
| * `storagePool` is the storage pool of the local array. | ||
| After figuring out how storage classes would look, you just need to go and apply them to your Kubernetes clusters with `kubectl`. | ||
| #### Storage Class creation with `repctl` | ||
| `repctl` can simplify storage class creation by creating a pair of mirrored storage classes in both clusters | ||
| (using a single storage class configuration) in one command. | ||
| To create storage classes with `repctl` you need to fill up the config with necessary information. | ||
| You can find an example [here](https://github.com/dell/csm-replication/blob/main/repctl/examples/unity_example_values.yaml), copy it, and modify it to your needs. | ||
| If you open this example you can see a lot of similar fields and parameters you can modify in the storage class. | ||
| Let's use the same example from manual installation and see what config would look like: | ||
| ```yaml | ||
| targetClusterID: "cluster-2" | ||
| sourceClusterID: "cluster-1" | ||
| name: "unity-replication" | ||
| driver: "unity" | ||
| reclaimPolicy: "Retain" | ||
| replicationPrefix: "replication.storage.dell.com" | ||
| remoteRetentionPolicy: | ||
| RG: "Retain" | ||
| PV: "Retain" | ||
| parameters: | ||
| arrayId: | ||
| source: "APM000000001" | ||
| target: "APM000000002" | ||
| storagePool: | ||
| source: pool_123 | ||
| target: pool_124 | ||
| rpo: "0" | ||
| ignoreNamespaces: "false" | ||
| volumeGroupPrefix: "prefix" | ||
| protocol: "NFS" | ||
| nasServer: | ||
| source: nas_123 | ||
| target: nas_123 | ||
| ``` | ||
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| After preparing the config, you can apply it to both clusters with `repctl`. Before you do this, ensure you've added your clusters to `repctl` via the `add` command. | ||
| To create storage classes just run `./repctl create sc --from-config <config-file>` and storage classes would be applied to both clusters. | ||
| After creating storage classes you can make sure they are in place by using `./repctl get storageclasses` command. | ||
| ### Provisioning Replicated Volumes | ||
| After installing the driver and creating storage classes, you are good to create volumes using newly | ||
| created storage classes. | ||
| On your source cluster, create a PersistentVolumeClaim using one of the replication-enabled Storage Classes. | ||
| The CSI Unity driver will create a volume on the array, add it to a VolumeGroup and configure replication | ||
| using the parameters provided in the replication enabled Storage Class. | ||
| ### Supported Replication Actions | ||
| The CSI Unity driver supports the following list of replication actions: | ||
| - FAILOVER_REMOTE | ||
| - UNPLANNED_FAILOVER_LOCAL | ||
| - REPROTECT_LOCAL | ||
| - SUSPEND | ||
| - RESUME | ||
| - SYNC |
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