VolumePlacementStrategy CRD reference
Portworx provides a CustomResouceDefinition (CRD) called VolumePlacementStrategy. The specification for this CRD is composed of 4 main sections:
Additional Information:
replicaAffinity
Schema
| Field | Description | Optional? | Default |
|---|---|---|---|
| enforcement | Specifies if the given rule is required (hard) or preferred (soft). Portworx will fail volume creation if it cannot provision volumes matching a rule with hard enforcement enabled. | Yes | required |
| matchExpressions | matchExpressions is a list of label selector requirements. The requirements are ANDed. The labels provided here are matched against the following:
|
Yes * * required if topologyKey is empty |
empty |
| topologyKey | Key for the node label that the system uses to denote a topology domain. The key can be for any node label that is present on the Kubernetes node.
NOTE: Using topologyKey requires nodes to be consistently labelled, i.e. every node in the cluster must have an appropriate label matching topologyKey. If some or all nodes are missing the specified topologyKey label, it can lead to unintended behavior.
|
Yes* * required if matchExpressions is empty |
empty |
| weight | Specifies the weight of the rule. If more than one rule matches, then the rule with the highest weight is applied. | Yes | 0 |
| affected_replicas | Specifies the number of volume replicas affected by this rule. | Yes | 0 (Interpreted as all volume replicas) |
Example use cases of replicaAffinity
- Use SSD pools
- Use SSD and SATA and spread replicas evenly
- First replica SSD, others SATA
- Place volume on specific nodes , example infra etc
- Place volume only on racks 1, 2 and 3
By default, Portworx automatically adds the following labels to each of its storage pools. These can be used for replica affinity rules to target replicas on a specific storage pool type:
ioprioritymedium (Media Type)
replicaAntiAffinity
Schema
| Field | Description | Optional? | Default |
|---|---|---|---|
| enforcement | Specifies if the given rule is required (hard) or preferred (soft). Portworx will fail volume creation if it cannot provision volumes matching a rule with hard enforcement enabled. | Yes | required |
| topologyKey | Key for the node label that the system uses to denote a topology domain. The key can be for any node label that is present on the Kubernetes node. Using topologyKey requires nodes to be consistently labelled, i.e. every node in the cluster must have an appropriate label matching topologyKey. If some or all nodes are missing the specified topologyKey label, it can lead to unintended behavior. | Yes* * required if matchExpressions is empty | empty |
Example use cases
volumeAffinity
Schema
| Field | Description | Optional? | Default |
|---|---|---|---|
| enforcement | Specifies if the given rule is required (hard) or preferred (soft) Portworx will fail volume creation if it cannot provision volumes matching a rule with hard enforcement enabled. | Yes | required |
| topologyKey | Key for the node label that the system uses to denote a topology domain. The key can be for any node label that is present on the Kubernetes node. Using topologyKey requires nodes to be consistently labelled, i.e. every node in the cluster must have an appropriate label matching topologyKey. If some or all nodes are missing the specified topologyKey label, it can lead to unintended behavior. |
Yes | empty |
| matchExpressions | matchExpressions is a list of label selector requirements. The requirements are ANDed. The labels provided here are matched against the following:
|
No | empty |
| weight | Specifies the weight of the rule. If more than one rule matches, then the rule with the highest weight is applied. | Yes | 0 |
Example use cases
volumeAntiAffinity
Schema
| Field | Description | Optional? | Default |
|---|---|---|---|
| enforcement | Specifies if the given rule is required (hard) or preferred (soft). Portworx will fail volume creation if it cannot provision volumes matching a rule with hard enforcement enabled. | Yes | required |
| topologyKey | Key for the node label that the system uses to denote a topology domain. The key can be for any node label that is present on the Kubernetes node. Using topologyKey requires nodes to be consistently labelled, i.e. every node in the cluster must have an appropriate label matching topologyKey. If some or all nodes are missing the specified topologyKey label, it can lead to unintended behavior. |
Yes | empty |
| matchExpressions | matchExpressions is a list of label selector requirements. The requirements are ANDed. The labels provided here are matched against the following:
|
No | empty |
Example use cases
topologyKey
If topologyKey is not set, by default the rule will avoid/colocate volumes at the node level using built-in unique node identifiers.
Portworx Built-in
topologyKey can use the built-in key portworx.io/pool that is set automatically as a unique key/value on every Portworx pool. This can be used with volumeAffinity/volumeAntiAffinity to control volume placement at the pool level to work for individual pools.
Templates
Parameter values in matchExpressions may use predefined templates. The VolumePlacementStrategy will automatically resolve these templates at provision time as detailed below:
- key:
namespace${pvc.namespace}- Replaced with namespace of the
PersistentVolumeClaimthat triggered provisioning - Example: Do not collocate with other app volumes within the same namespace
- Replaced with namespace of the
- key:
px/statefulset-pod${pvc.statefulset-pod}- Replaced with the
StatefulSetpod name thePersistentVolumeClaimbelongs to - Matches corresponding label key/value applied to the volume
- Use this with multiple
volumeClaimTemplatesin aStatefulSetto relate volumes for the same replica pod to each other - Works with
Immediatebinding mode - Example: Collocate volumes that belong to the same StatefulSet pod
- Replaced with the
Last edited: Tuesday, May 9, 2023
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