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Update docs with topology aware dynamic provisioning #9939

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Sep 11, 2018
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Update docs with topology aware dynamic provisioning #9939

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9bdfeae
Document topology aware volume binding feature
msau42 Sep 7, 2018
6655d3f
update for readability
zparnold Sep 9, 2018
c11b1de
Update storage-classes.md
zparnold Sep 9, 2018
8f7001f
comma splice
zparnold Sep 9, 2018
9988866
don't abbreviate
msau42 Sep 10, 2018
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21 changes: 10 additions & 11 deletions content/en/docs/concepts/storage/storage-classes.md
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Expand Up @@ -133,15 +133,14 @@ provisioning](/docs/concepts/storage/persistent-volumes/#provisioning) should oc

By default, the `Immediate` mode indicates that volume binding and dynamic
provisioning occurs once the PVC is created. For storage
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Should we indicate here that PVC == PersistentVolumeClaim?

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It doesn't hurt to be explicit.

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PVC and PersistentVolumeClaim were introduced at the beginning of this page

backends that are topology-constrained and not globally accessible from all nodes
in the cluster (for example, a zonal disk, or a local volume), this causes
volumes to be bound or provisioned without knowledge of the pod's scheduling
requirements, and can result in unschedulable pods.

To address this issue, the `WaitForFirstConsumer` mode can be specified which
will delay binding and provisioning until a pod using the PVC is created.
Volumes will be selected or provisioned with the appropriate topology that is
compatible with the pod's scheduling constraints, including but not limited to, [resource
backends that are topology-constrained and not globally accessible from all Nodes
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Will it be possible to keep the examples of common topology-constrained volume types [a zonal disk like EBS/GCE PD/Azure Managed disk or a local volume] as was specified earlier? It helps the reader understands where WaitForFirstConsumer is specifically applicable.

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The list of supported plugins is below. Is that what you meant?

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Ah yes, that should be good.

in the cluster, Volumes will be bound or provisioned without knowledge of the Pod's scheduling
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Volumes => PVs

requirements. This may result in unschedulable Pods.

A cluster administrator can address this issue by specifying the `WaitForFirstConsumer` mode which
will delay the binding and provisioning of a Volume until a Pod using the PVC is created.
Volumes will be selected or provisioned conforming to the topology that is
specified by the Pod's scheduling constraints. These include, but are not limited to, [resource
requirements](/docs/concepts/configuration/manage-compute-resources-container),
[node selectors](/docs/concepts/configuration/assign-pod-node/#nodeselector),
[pod affinity and
Expand All @@ -165,11 +164,11 @@ The following plugins support `WaitForFirstConsumer` with pre-created PV binding
**Note:** This feature requires the `VolumeScheduling` feature gate to be
enabled.

When `WaitForFirstConsumer` volume binding mode is specified, it is no longer necessary
When a cluster operactor specifies the `WaitForFirstConsumer` volume binding mode, it is no longer necessary
to restrict provisioning to specific topologies in most situations. However,
if still required, `allowedTopologies` can be specified.

This example demonstrates how to restrict topology of provisioned volumes to specific
This example demonstrates how to restrict the topology of provisioned volumes to specific
zones and should be used as a replacement for the `zone` and `zones` parameters for the
supported plugins.

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