Support for multiple storage directories (#296)

# Description Fixes #274

Author: sbernauer

CHANGELOG.md

@@ -7,6 +7,7 @@ All notable changes to this project will be documented in this file.
 ### Added
 
 - Log aggregation added ([#290]).
+- Support for multiple storage directories ([#296]).
 
 ### Changed
 
@@ -21,6 +22,7 @@ All notable changes to this project will be documented in this file.
 [#281]: https://github.com/stackabletech/hdfs-operator/pull/281
 [#286]: https://github.com/stackabletech/hdfs-operator/pull/286
 [#290]: https://github.com/stackabletech/hdfs-operator/pull/290
+[#296]: https://github.com/stackabletech/hdfs-operator/pull/296
 
 ## [0.6.0] - 2022-11-07
 

deploy/helm/hdfs-operator/crds/crds.yaml

@@ -192,7 +192,52 @@ dataNodes:
 
 In the above example, all data nodes in the default group will store data (the location of `dfs.datanode.name.dir`) on a `128Gi` volume.
 
-By default, in case nothing is configured in the custom resource for a certain role group, each Pod will have a `1Gi` large local volume mount for the data location.
+By default, in case nothing is configured in the custom resource for a certain role group, each Pod will have a `5Gi` large volume mount for the data location.
+
+==== Multiple storage volumes
+
+Datanodes can have multiple disks attached to increase the storage size as well as speed.
+They can be of different type, e.g. HDDs or SSDs.
+
+You can configure multiple [PersistentVolumeClaims](https://kubernetes.io/docs/concepts/storage/persistent-volumes/#persistentvolumeclaims) (PVCs) for the datanodes as follows:
+
+[source,yaml]
+----
+dataNodes:
+ roleGroups:
+ default:
+ config:
+ resources:
+ storage:
+ data: # We need to overwrite the data pvcs coming from the default value
+ count: 0
+ my-disks:
+ count: 3
+ capacity: 12Ti
+ hdfsStorageType: Disk
+ my-ssds:
+ count: 2
+ capacity: 5Ti
+ storageClass: premium-ssd
+ hdfsStorageType: SSD
+----
+
+This will create the following PVCs:
+
+1. `my-disks-hdfs-datanode-default-0` (12Ti)
+2. `my-disks-1-hdfs-datanode-default-0` (12Ti)
+3. `my-disks-2-hdfs-datanode-default-0` (12Ti)
+4. `my-ssds-hdfs-datanode-default-0` (5Ti)
+5. `my-ssds-1-hdfs-datanode-default-0` (5Ti)
+
+By configuring and using a dedicated https://kubernetes.io/docs/concepts/storage/storage-classes/[StorageClass] you can configure your HDFS to use local disks attached to Kubernetes nodes.
+
+[NOTE]
+====
+You might need to re-create the StatefulSet to apply the new PVC configuration because of https://github.com/kubernetes/kubernetes/issues/68737[this Kubernetes issue].
+You can delete the StatefulSet using `kubectl delete sts --cascade=false <statefulset>`.
+The hdfs-operator will re-create the StatefulSet automatically.
+====
 
 === Resource Requests
 

deploy/manifests/crds.yaml

@@ -50,3 +50,13 @@ pub const DFS_HA_NAMENODES: &str = "dfs.ha.namenodes";
 // core-site.xml
 pub const FS_DEFAULT_FS: &str = "fs.defaultFS";
 pub const HA_ZOOKEEPER_QUORUM: &str = "ha.zookeeper.quorum";
+
+pub const STACKABLE_ROOT_DATA_DIR: &str = "/stackable/data";
+pub const NAMENODE_ROOT_DATA_DIR: &str = "/stackable/data/namenode";
+pub const JOURNALNODE_ROOT_DATA_DIR: &str = "/stackable/data/journalnode";
+
+// Will end up with something like `/stackable/data/<pvc-name>/datanode` e.g. `/stackable/data/data/datanode` and `/stackable/data/data-1/datanode` etc.
+// We need one additional level because we don't want users to call their pvc e.g. `hadoop`
+// ending up with a location of `/stackable/hadoop/data`
+pub const DATANODE_ROOT_DATA_DIR_PREFIX: &str = "/stackable/data/";
+pub const DATANODE_ROOT_DATA_DIR_SUFFIX: &str = "/datanode";