Volume Placement Strategy CRD reference in OCP GCP
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 OpenShift 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:
iopriority
medium (Media Type)