mirror of https://gitee.com/bigwinds/arangodb
135 lines
3.9 KiB
Markdown
135 lines
3.9 KiB
Markdown
<!-- don't edit here, its from https://@github.com/arangodb/kube-arangodb.git / docs/Manual/ -->
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# Storage
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An ArangoDB cluster relies heavily on fast persistent storage.
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The ArangoDB Kubernetes Operator uses `PersistentVolumeClaims` to deliver
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the storage to Pods that need them.
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## Storage configuration
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In the `ArangoDeployment` resource, one can specify the type of storage
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used by groups of servers using the `spec.<group>.storageClassName`
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setting.
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This is an example of a `Cluster` deployment that stores its agent & dbserver
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data on `PersistentVolumes` that use the `my-local-ssd` `StorageClass`
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```yaml
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apiVersion: "database.arangodb.com/v1alpha"
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kind: "ArangoDeployment"
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metadata:
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name: "cluster-using-local-ssh"
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spec:
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mode: Cluster
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agents:
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storageClassName: my-local-ssd
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dbservers:
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storageClassName: my-local-ssd
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```
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The amount of storage needed is configured using the
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`spec.<group>.resources.requests.storage` setting.
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Note that configuring storage is done per group of servers.
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It is not possible to configure storage per individual
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server.
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This is an example of a `Cluster` deployment that requests volumes of 80GB
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for every dbserver, resulting in a total storage capacity of 240GB (with 3 dbservers).
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```yaml
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apiVersion: "database.arangodb.com/v1alpha"
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kind: "ArangoDeployment"
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metadata:
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name: "cluster-using-local-ssh"
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spec:
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mode: Cluster
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dbservers:
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resources:
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requests:
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storage: 80Gi
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```
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## Local storage
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For optimal performance, ArangoDB should be configured with locally attached
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SSD storage.
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The easiest way to accomplish this is to deploy an
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[`ArangoLocalStorage` resource](./StorageResource.md).
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The ArangoDB Storage Operator will use it to provide `PersistentVolumes` for you.
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This is an example of an `ArangoLocalStorage` resource that will result in
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`PersistentVolumes` created on any node of the Kubernetes cluster
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under the directory `/mnt/big-ssd-disk`.
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```yaml
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apiVersion: "storage.arangodb.com/v1alpha"
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kind: "ArangoLocalStorage"
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metadata:
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name: "example-arangodb-storage"
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spec:
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storageClass:
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name: my-local-ssd
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localPath:
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- /mnt/big-ssd-disk
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```
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Note that using local storage required `VolumeScheduling` to be enabled in your
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Kubernetes cluster. ON Kubernetes 1.10 this is enabled by default, on version
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1.9 you have to enable it with a `--feature-gate` setting.
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### Manually creating `PersistentVolumes`
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The alternative is to create `PersistentVolumes` manually, for all servers that
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need persistent storage (single, agents & dbservers).
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E.g. for a `Cluster` with 3 agents and 5 dbservers, you must create 8 volumes.
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Note that each volume must have a capacity that is equal to or higher than the
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capacity needed for each server.
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To select the correct node, add a required node-affinity annotation as shown
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in the example below.
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```yaml
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apiVersion: v1
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kind: PersistentVolume
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metadata:
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name: volume-agent-1
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annotations:
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"volume.alpha.kubernetes.io/node-affinity": '{
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"requiredDuringSchedulingIgnoredDuringExecution": {
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"nodeSelectorTerms": [
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{ "matchExpressions": [
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{ "key": "kubernetes.io/hostname",
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"operator": "In",
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"values": ["node-1"]
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}
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]}
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]}
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}'
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spec:
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capacity:
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storage: 100Gi
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accessModes:
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- ReadWriteOnce
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persistentVolumeReclaimPolicy: Delete
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storageClassName: local-ssd
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local:
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path: /mnt/disks/ssd1
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```
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For Kubernetes 1.9 and up, you should create a `StorageClass` which is configured
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to bind volumes on their first use as shown in the example below.
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This ensures that the Kubernetes scheduler takes all constraints on a `Pod`
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that into consideration before binding the volume to a claim.
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```yaml
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kind: StorageClass
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apiVersion: storage.k8s.io/v1
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metadata:
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name: local-ssd
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provisioner: kubernetes.io/no-provisioner
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volumeBindingMode: WaitForFirstConsumer
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```
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