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KumoScale Overview

For more information on KumoScale software defined NVMe-oF storage go to https://kumoscale.kioxia.com

kumoscale-csi-plugin

The ks-csi-plugin enables storage provisioning from Kubernetes(R) on top of KumoScaleTM and provisioner. See the ks-csi.yaml on how to deploy on Kubernetes cluster. You also need to update the versions of the ks-csi-plugin image. The current version of ks-clsi-plugin requires Kubernetes version >= 14.1. Use ks-csi.yaml for kube version >= 1.16 and ks-csi15.yaml for kube version which is < 1.16 .

Kubernetes install preparation

  1. Download ks-csi-plugin-v1.4.244.tar.gz
  2. Upload this driver image file to local container registry with appropriate tag

Kubernetes install instructions

  1. Download the yaml example artifacts
  2. Edit the provisioner-secret.yaml and provide the provisioner url , kumoscale-generated token and optionaly tenantId of an existing provisioner tenant.
  3. Create the secret: kubectl create -f provisioner-secret.yaml
  4. Edit the install yaml: ks-csi.yaml with required parameters as explained above. If kublet is running with non default root directory (the default root directory is /var/lib/kubelet) You need to replace every occurence of /var/lib/kubelet in the instalation yaml with with the root directory which is in use.
  5. Install the driver with: kubectl create -f ks-csi.yaml

Kubernetes - Provision storage from KumoScale and provisioner

  1. Create a storage class with one of the examples, for example: kubectl create -f provisioner-storage-class.yaml The CSI plug-in supports the following parameters in the storage class: See storage class parameters summary bellow for supported options
  2. Create a persistent volume claim (PVC) with one of the example which is based on the storage class you've created.
  3. Create a pod based on the PVC.

Kubernetes - Expanding volumes

  1. Kubernetes 'Expand Volume' is in Beta (1.15) and Alpha (1.14), therefor, it needs to be enabled by --feature-gates=ExpandCSIVolumes=true,ExpandInUsePersistentVolumes=true in centos kube do: a) In all kube nodes : Edit /var/lib/kubelet/kubeadm-flags.env : Add the above feature gates to the variable KUBELET_KUBEADM_ARGS . b) In master do: add the feature gates to api server in file : /etc/kubernetes/manifests/kube-apiserver.yaml
  2. To expand a volume, the storage class needs to enable it by setting: allowVolumeExpansion: true See example in storage class yamls.
  3. A special secret should be created with the namespace kube-system and the name kumoscale-provisioner. This secret should contain the provisioner url and token. You can use the provisioner-secret.yaml from the example for this purpose
  4. To expand a volume , you need to edit the PVC: kubectl edit pvc Simply enlarge the pvc size under spec->storage Allow 1-2 minutes for the expansion to occur, as it take some time for kube to notice the change and perform the expansion.

Kubernetes - Snapshots

  1. Kubernetes 'Snapshots' is in Alpha (1.16), therefor, it needs to be enabled by --feature-gates=VolumeSnapshotDataSource=true See 'Expand Volume' section on how to enable feature gates.
  2. To create a snapshot, you first need to create a VolumeSnapshotClass - see SnapshotClass.yaml for example. You can specify the reservedSpace for snapshots of this class in percentage from the original volume size.
  3. Create a PVC with a storage class which has replicas=1 (use kube1PVC.yaml for example)
  4. Create a snapshot with a snapshot yaml that refers to the created PVC(See Snapshot.yaml example)
  5. Create a snapshot volume with a snapshot volume yaml (See SnapshotVolume.yaml example)
  6. Deletion needs to be in the same order (first delete the snashot volume then, the snapshot and then the volume)

Kubernetes - Storage Class Parameters Summary

File system type: (supported types ext2,ext3,ext4,xfs default : ext4) : #csi.storage.k8s.io/fstype: "xfs"

Number of replicas (default 1): #numReplicas: "1"

Allow replicas on KumoScales from the same rack (boolean : default "false"): #sameRackAllowed: "false" Limit IOPS on volumes - per giga byte (default - "0" - unlimmited ) #maxIOPSPerGB : "0" Desired IOPS for volume - per gig byte (default - "0" - not set) #desiredIOPSPerGB: "0" Limit bandwidth on volumes - per giga byte, in KB/sec (default - "0" - unlimmited ) #maxBWPerGB: "0" Desired bandwidth on volumes - per giga byte,in KB/sec (default - "0" - not set) #desiredBWPerGB: "0" Volume block size - Volume and file system block size (default 4096) #blockSize: "4096" The space to reserve for snapshot volume changes in (%) from from total size #default 10 reservedSpacePercentage: "20"

Specify whether snapshot volumes from this class are writable or not #default true writable: "true"

Select thick for thick volume or thin for thin volume - default thick #provisioningType: "thick"

Kubernetes - Collecting Logs

To collect logs for each container (ks-csi-plugin) you can use kubectl logs. For example, to collect controller logs run: kubectl logs -n kube-system csi-kumoscale-controller-0 ks-csi-plugin > controller.log

Kubernetes - CSI topology supported

CSI topology features enables volume allocation on backends which are accessible to nodes. In order to enable this feature the user needs to:

  1. Set volumeBindingMode: WaitForFirstConsumer in the storage class - So that pvc allocation will be done when a pod that refers it starts running for the first time
  2. Label each of Kubernetes nodes with topology labels: failure-domain.beta.kubernetes.io/region failure-domain.beta.kubernetes.io/zone Note: after labeling nodes, you need to redploy the csi driver.
  3. Set region ,zone, rack to backends (use REST command update backend or add backend)
  4. Check that when a pod is assigned to a node, the volume is allocated on backend within the same region and zone of the node when possible (such backend exist with enough capacity)