storage

Red Hat OpenShift Container Platform supports the use of Fibre Channel (FC) based storage that allows users to provision volumes based on it. The Kubernetes persistent volume framework allows users to request those resources without knowledge of the underlying storage infrastructure.

This article provides information on how we can configure and use Dell’s Powermax Storage on OpenShift 4 clusters with the help of the Dell CSI Operator. The Dell Powermax in addition has the capabilities for expansion and snapshots of volumes provisioned of it.

The Dell CSI Operator is a Kubernetes Operator, which can be used to install and manage the CSI Drivers provided by Dell for various storage platforms. This operator is available as a community operator and certified operator for OpenShift clusters and can be deployed using the OpenShift Container Platform. Both these methods of installation use OLM (Operator Lifecycle Manager). The operator can also be deployed manually. 

Prerequisites

Before we proceed with the installation of the Operator, the following prerequisites are required as part of the installation.

Multipath

Multipath configured across all compute nodes.

  • Create the base64 contents for multipath configuration as follows

       echo 'defaults {
    user_friendly_names yes
    find_multipaths yes
    }
    blacklist {
    }' | base64 -w0
    ZGVmYXVsdHMgewoKdXNlcl9mcmllbmRseV9uYW1lcyB5ZXMKCmZpbmRfbXVsdGlwYXRocyB5ZXMKCn0KCmJsYWNrbGlzdCB7Cgp9Cg==
  • Create a MachineConfig file and specify the above contents to it.

    apiVersion: machineconfiguration.openshift.io/v1
    kind: MachineConfig
    metadata:
    name: multipath-conf-default
    labels:
    machineconfiguration.openshift.io/role: worker
    spec:
    config:
    ignition:
    version: 3.1.0
    storage:
    files:
    - contents:
    source: data:text/plain;charset=utf-8;base64,ZGVmYXVsdHMgewoKdXNlcl9mcmllbmRseV9uYW1lcyB5ZXMKCmZpbmRfbXVsdGlwYXRocyB5ZXMKCn0KCmJsYWNrbGlzdCB7Cgp9Cg==
    verification: {}
    filesystem: root
    mode: 400
    path: /etc/multipath.conf
    # oc apply -f machineconfig.yaml 

This triggers an mcp update and you can find all the nodes in updating state for which the changes are being applied and then the nodes being restarted. This enables and starts the service on the compute nodes.

Secret

  • We are required to configure the secret with user access to the Powermax management console. NOTE: The secret needs to be configured with the name powermax-creds.

    apiVersion: v1
    kind: Secret
    metadata:
    name: powermax-creds
    namespace: dell-storage-powermax
    type: Opaque
    data:
    # specify base64 creds
    username: <base64 contents of username>
    password: <base64 contents of password>

This is created into the namespace dell-storage-powermax in our case that we will be using for deploying our Powermax custom resource that was previously created.

Installation

The installation of the operator in OCP4 can be done directly from the OperatorHub. Once selected, we can proceed with the Install of the operator to all the namespaces with it installed on the NS openshift-operators. This starts the operator pod in the namespace

❯ oc get pods -n openshift-operators

NAME READY STATUS RESTARTS AGE

dell-csi-operator-controller-manager-9ff7f55bc-96hgw 1/1 Running 0 7m48s

The installation of the Operator provides us with the API functionalities or CRD’s configured for the following resources

  • CSI PowerScale
  • CSI PowerMax
  • CSI PowerMax ReverseProxy
  • CSI PowerStore
  • CSI Unity XT
  • CSI PowerFlex

In our case, we will be configuring CSI Powermax for this.

Configuration

Custom Resource - PowerMax

Next, we are required to create the Powermax custom resource that includes information about the array details, management endpoint Address, 3 letter keyword as cluster prefixes for volumes provisioned by the storage and transport protocol. This can be done either via the UI or console having included the necessary information

csipowerma

This will create the powermax controller pods along with powermax pods running on each of the compute nodes. If you have multiple compute nodes for different roles or purposes, it would be best to configure a nodeselector on the project and add the label to the nodes so that the powermax pods are only running on them specifically or this can be achieved using the node topology keys.

$ oc get pods -n dell-storage-powermax

NAME READY STATUS RESTARTS AGE

powermax-controller-332f6cvf-453ff 5/5 Running 0 101s
powermax-controller-332f6cvf-ser34 5/5 Running 0 101s
powermax-node-594v4 2/2 Running 0 101s
powermax-node-r8tgl 2/2 Running 0 101s
powermax-node-rkm7g 2/2 Running 0 101s

The logs for the container driver in powermax-node when accessed will be having information on the HBA’s being discovered and logging into these devices.

StorageClass

We can now proceed with the installation of the SC based on the YAML file below or from the UI where the provisioner needs to be specified as CSI powermax. The storage filesystem type if not specified resorts to ext4 by default.

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: powermaxsc
parameters:
csi.storage.k8s.io/fstype: xfs
SRP: SRP_1
SYMID: "000497600159"
ServiceLevel: “Diamond”
provisioner: csi-powermax.dellemc.com
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true

The above SC yaml can be applied on the cluster

$ oc apply -f storage_class.yaml

$ oc get sc

NAME PROVISIONER AGE
powermaxsc csi-powermax.dellemc.com 50s

This creates the StorageClass on the cluster with CSI Powermax.

Provisioning FC Volumes

With the storage class made available to all users, this allows the provision of FC volumes of it. Once you create a PVC, this will be in WaitForFirstConsumer state till it gets attached to a pod.

# Create a PVC 
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: fc-powermax-volume-1
namespace: my-test-namespace
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 5Gi
storageClassName: powermaxsc

$ oc create -f pvc.yaml
$ oc get pvc -n my-test-namespace

NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
fc-powermax-volume-1 WaitForFirstConsumer 5Gi RWO powermaxsc
# Create a pod and attach the volume.

apiVersion: v1
kind: Pod
metadata:
name: example
namespace: my-test-namespace
spec:
containers:
- name: test-pvc-powermax
image: quay.io/centos/centos
ports:
- containerPort: 80
name: "http-server"
volumeMounts:
- mountPath: "/mnt"
name: fc
command: ["/bin/bash", "-c", "cp /tmp/keys /mnt/keys && sleep 2000000000"]
volumes:
- name: fc
persistentVolumeClaim:
claimName: fc-powermax-volume-1
$ oc create -f pod.yaml

This starts the provisioning of the volume on the Dell SAN storage side and once done attach’s it to the node and starts the pod for this.

Below are the events that pertain to this.

LAST        SEEN          TYPE            REASON                   OBJECT                                           MESSAGE
24m Normal WaitForFirstConsumer persistentvolumeclaim/fc-powermax-volume-1 waiting for first consumer to be created before binding

24m Normal Provisioning persistentvolumeclaim/fc-powermax-volume-1 External provisioner is provisioning volume for claim "my-test-namespace/fc-powermax-volume-1"

24m Normal ExternalProvisioning persistentvolumeclaim/fc-powermax-volume-1 waiting for a volume to be created, either by external provisioner "csi-powermax.dellemc.com" or manually created by system administrator

24m Normal ProvisioningSucceeded persistentvolumeclaim/fc-powermax-volume-1 Successfully provisioned volume pmax-a23bdd02ab

24m Normal Scheduled pod/example Successfully assigned my-test-namespace/example to worker-1-region-2

24m Normal SuccessfulAttachVolume pod/example AttachVolume.Attach succeeded for volume "pmax-a23bdd02ab"

24m Normal AddedInterface pod/example Add eth0 [100.121.35.203/22] from ovn-kubernetes

24m Normal Pulling pod/example Pulling image "quay.io/centos/centos:latest"

24m Normal Pulled pod/example Successfully pulled image "quay.io/centos/centos:latest" in 7.176869952s

24m Normal Created pod/example Created container test-pvc-powermax
24m Normal Started pod/example Started container test-pvc-powermax

We are able to rsh/login to the pod once created to verify the volume that was created.

$ oc rsh example

sh-4.4# df -h

Filesystem Size Used Avail Use% Mounted on

overlay 1.5T 66G 1.4T 5% /

tmpfs 64M 0 64M 0% /dev

tmpfs 252G 0 252G 0% /sys/fs/cgroup

shm 64M 0 64M 0% /dev/shm

tmpfs 252G 90M 252G 1% /etc/hostname

/dev/mapper/mpatha 5G 10M 5G 1% /mnt

/dev/mapper/coreos-luks-root-encrypt 1.5T 66G 1.4T 5% /tmp

tmpfs 503G 20K 503G 1% /run/secrets/kubernetes.io/serviceaccount

tmpfs 252G 0 252G 0% /proc/acpi

tmpfs 252G 0 252G 0% /proc/scsi

tmpfs 252G 0 252G 0% /sys/firmware

This successfully completes the provisioning of volumes on Dell PowerMax

Conclusion

The Dell Powermax has advantages such as volume expansion that allows to expand PVC’s even when the pod is running. In addition, it allows a snapshot of the volume that helps to back up data to a point in time and then have it restored on user namespaces. If you run into issues during configuring or provisioning of this Storage you can always gather information from the driver container in powermax-controller pod or specific node level driver containers for extracting more information and raise a support case with Red Hat or the vendor.

Hope this helped give you an insight into how FC storage can be configured on OpenShift 4.x for your application development teams.

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