Disk Provisioning on VMware vSphere


This guide explains how the Portworx Dynamic Disk Provisioning feature works within Kubernetes on VMware and the requirements for it.

Installation steps below are only supported if you are running with Kubernetes.

Architecture

Below diagram gives an overview of the Portworx architecture on vSphere using shared datastores.

  • Portworx runs as a Daemonset hence each Kubernetes minion/worker will have the Portworx daemon running.
  • Based on the given spec by the end user, Portworx on each node will create it’s disk on the configured shared datastore(s) or datastore cluster(s).
  • Portworx will aggregate all of the disks and form a single storage cluster. End users can carve PVCs (Persistent Volume Claims), PVs (Persistent Volumes) and Snapshots from this storage cluster.
  • Portworx tracks and manages the disks that it creates. So in a failure event, if a new VM spins up, Portworx on the new VM will be able to attach to the same disk that was previously created by the node on the failed VM.

Portworx architecture for PKS on vSphere using shared datastores or datastore clusters

Limiting storage nodes

PX allows you to create a heterogenous cluster where some of the nodes are storage nodes and rest of them are storageless.

You can specify the number of storage nodes in your cluster by setting the max_storage_nodes_per_zone input argument. This instructs PX to limit the number of storage nodes in one zone to the value specified in max_storage_nodes_per_zone argument. The total number of storage nodes in your cluster will be

Total Storage Nodes = (Num of Zones) * max_storage_nodes_per_zone.

While planning capacity for your auto scaling cluster make sure the minimum size of your cluster is equal to the total number of storage nodes in PX. This ensures that when you scale up your cluster, only storage less nodes will be added. While when you scale down the cluster, it will scale to the minimum size which ensures that all PX storage nodes are online and available.

You can always ignore the max_storage_nodes_per_zone argument. When you scale up the cluster, the new nodes will also be storage nodes but while scaling down you will loose storage nodes causing PX to loose quorum.

Examples:

  • "-s", "type=zeroedthick,size=200", "-max_storage_nodes_per_zone", "1"

For a cluster of 6 nodes spanning 3 zones (zone-1a,zone-1b,zone-1c), in the above example PX will have 3 storage nodes (one in each zone) and 3 storage less nodes. PX will create a total 3 disks of size 200 each and attach one disk to each storage node.

  • "-s", "type=zeroedthick,size=200", "-s", "type=zeroedthick,size=100", "-max_storage_nodes_per_zone", "2"

For a cluster of 9 nodes spanning 2 zones (zone-1a,zone-1b), in the above example PX will have 4 storage nodes and 5 storage less nodes. PX will create a total of 8 disks (4 of size 200 and 4 of size 100). PX will attach a set of 2 disks (one of size 200 and one of size 100) to each of the 4 storage nodes.

Availability across failure domains

Since PX is a storage overlay that automatically replicates your data, we recommend using multiple availability zones when creating your VMware vSphere based cluster. Portworx automatically detects regions and zones that are populated using known Kubernetes node labels. You can also label nodes with custom labels to inform Portworx about region, zones and racks. The page Cluster Topology awareness explains this in more detail.

Installation

Run these steps from a machine which has kubectl access to your cluster.

Step 1: vCenter user for Portworx

You will need to provide Portworx with a vCenter server user that will need to either have the full Admin role or, for increased security, a custom-created role with the following minimum vSphere privileges:

  • Datastore
    • Browse datastore
    • Low level file operations
    • Remove file
  • Host
    • Local operations
    • Reconfigure virtual machine
  • Virtual machine
    • Change Configuration
    • Add existing disk
    • Add new disk
    • Add or remove device
    • Advanced configuration
    • Change Settings
    • Modify device settings
    • Remove disk

If you create a custom role as above, make sure to select “Propagate to children” when assigning the user to the role.

All commands in the subsequent steps need to be run on a machine with kubectl access.

Step 2: Create a Kubernetes secret with your vCenter user and password

Update the following items in the Secret template below to match your environment:

  1. VSPHERE_USER: Use output of printf <vcenter-server-user> | base64
  2. VSPHERE_PASSWORD: Use output of printf <vcenter-server-password> | base64
apiVersion: v1
kind: Secret
metadata:
  name: px-vsphere-secret
  namespace: kube-system
type: Opaque
data:
  VSPHERE_USER: YWRtaW5pc3RyYXRvckB2c3BoZXJlLmxvY2Fs
  VSPHERE_PASSWORD: cHgxLjMuMEZUVw==

kubectl apply the above spec after you update the above template with your user and password.

Step 3: Generate rest of the specs

vSphere environment details

Export following env variables based on your vSphere environment. These variables will be used in a later step when generating the yaml spec.

# Hostname or IP of your vCenter server
export VSPHERE_VCENTER=myvcenter.net

# Prefix of your shared ESXi datastore(s) names. Portworx will use datastores who names match this prefix to create disks.
export VSPHERE_DATASTORE_PREFIX=mydatastore-

# Change this to the port number vSphere services are running on if you have changed the default port 443
export VSPHERE_VCENTER_PORT=443

Disk templates

A disk template defines the VMDK properties that Portworx will use as a reference for creating the actual disks out of which Portworx will create the virtual volumes for your PVCs.

Following example will create a 150GB zeroed thick vmdk on each VM.

export VSPHERE_DISK_TEMPLATE=type=zeroedthick,size=150

The template follows the following format:

"type=<vmdk type>,size=<size of the vmdk>"
  • type: Supported types are thin, zeroedthick , eagerzeroedthick
  • size: This is the size of the VMDK in GiB

Generate the spec file

Now generate the spec with the following curl command.

Observe how curl below uses the environment variables setup up above as query parameters.
export VER=$(kubectl version --short | awk -Fv '/Server Version: /{print $3}')
curl -fsL -o px-spec.yaml "https://install.portworx.com/2.2?kbver=$VER&c=portworx-demo-cluster&b=true&st=k8s&csi=true&vsp=true&ds=$VSPHERE_DATASTORE_PREFIX&vc=$VSPHERE_VCENTER&s=%22$VSPHERE_DISK_TEMPLATE%22"

Apply the specs

Apply the generated specs to your cluster.

kubectl apply -f px-spec.yaml
Monitor the portworx pods

Wait till all Portworx pods show as ready in the below output:

kubectl get pods -o wide -n kube-system -l name=portworx
Monitor Portworx cluster status
PX_POD=$(kubectl get pods -l name=portworx -n kube-system -o jsonpath='{.items[0].metadata.name}')
kubectl exec $PX_POD -n kube-system -- /opt/pwx/bin/pxctl status



Last edited: Friday, Oct 4, 2019