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Dense Mode and Node Pools

Cloud service provider relevance: AKS

AKS Node Pools​

In AKS, nodes with the same configuration are grouped into node pools containing the underlying VMs that run your applications.

node-pools-list

In Ocean, each virtual node group manages its own set of node pools.

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AKS is responsible for launching VMs with the given configuration and registering them with the cluster. Ocean uses the node pool data to get information about a VM.

Dense Scaling Mode​

For Ocean with AKS, new nodes are scaled up using AKS’s node pools in accordance with the native AKS method for launching nodes.

Due to the limited number of node pools in AKS clusters, Ocean considers market density and scales from existing node pools.

In normal operation, Ocean creates new node pools to extend the number of markets.

Under normal operating conditions, other services recycle node pools to maintain alignment with cluster settings (such as specific SKUs, VM replacements, and spot availability). However, these processes require the ability to create new node pools.

Ocean switches to dense scaling mode when one of these conditions is met:

  • Active node pools in the virtual node group reach saturation (determined dynamically by an algorithm). When this happens, Ocean scales node pools in dense mode without affecting other virtual node groups.

  • The cluster uses an unsupported Azure AKS version: When the cluster's AKS version is no longer supported by Azure, new node pool creation is disabled (an Azure AKS limitation). Ocean switches to dense mode and scales using only existing node pools.

In dense mode, Ocean only uses existing node pools for scaling operations and does not create new ones.

View Node Pools in the Console​

To access the Node pools tab:

  • Click Ocean > Cloud Clusters on the left main menu.
  • Select a cluster from the list of clusters.
  • Click the Node Pools tab.
Click to view image

The node pools list contains these columns:

  • Node Pool: Click on the link to open the node pool details, attributes, and list of nodes (in the Nodes tab).
    • You can sort this column by either name or status.
  • Virtual Node Group: Click on the link to open the configuration for the virtual node group.
  • Availability Zone: Availability zone for the node pool.
  • VM Size: Machine type.
  • Life Cycle: Regular or spot.
  • Node Count: Number of nodes in the node pool.
  • OS: For example, Linux.
  • OS Disk: Ephemeral or managed.
  • OS SKU: For example, Ubuntu.
  • Image: Image name.
  • K8s version: Kubernetes version number.

Node Pool Status​

  • icon-successful-20 Running successfully.
  • icon-spinner Spinner (node pool being processed).
  • icon-lock Locked. When a node pool is locked in Azure, modifications, scaling, or deletions by Ocean are restricted to ensure stability and prevent unintended changes. The locking mechanism helps maintain operational integrity during critical operations.
  • icon-warmedup Warmed-up: Node pool that has been pre-provisioned and is ready to manage workloads:
    • Pre-provisioning: Nodes in a warmed-up pool are created in advance, which reduces the time needed to scale up when traffic increases. This helps ensure that applications can respond quickly to sudden spikes in demand.
    • The nodes are ready, meaning they are fully initialized and can accept pods without the delay associated with starting new nodes from scratch.
    • Use case: This is particularly useful for applications with predictable traffic patterns, improving performance and reliability.
  • icon-unmanaged1 Unmanaged Node Pool.