reclaim_policy.md

title	authors	owners	creation-date	last-updated	status
ReclaimPolicy	k8s storage contributors	k8s storage contributors	2021-06-16	2021-06-16	Implemented

StorageClass Volume Reclaim Policy

Table of Contents

• StorageClass Volume Reclaim Policy
• Table of Contents
• Summary
• Motivation
  • Goals
• Proposal
  • Implementation Details
  • Usage Details
  • Test Plan
• Graduation Criteria
• Drawbacks
• Alternatives

Summary

This proposal points out workflow details of volume reclaim policies.

Motivation

Goals

• As a user, I should be able to retain underlying LVM Volume even after deleting PVC.
• As a user, I should be able to delete LVM volume after deleting PVC.

Proposal

Implementation Details

LocalPV-LVM doesn't have any direct dependency over volume reclaim policies moreover these are is a standard Kubernetes storageclass option. Kubernetes supports two kind of volume policies that are Retain & Delete. By the name Retain states underlying volume should exist even after deleting PVC whereas Delete states underlying volume should be deleted and space should be reclaimed to serve a different purpose.

• If reclaim policy is Delete then external-provisioner will make DeleteVolume gRPC request to CSI-Driver.
• If reclaim policy is Retain then external-provisioner will not issue any gRPC request to CSI-Driver.

Note: If ReclaimPolicy is unspecified then defaults of Delete policy.

Usage Details

• User/Admin can specify the type of Reclaim policy under StorageClass options.

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: openebs-lvm
provisioner: local.csi.openebs.io
parameters:
  storage: "lvm"
  vgpattern: "lvmvg.*"
reclaimPolicy: Delete          ## Reclaim policy can be specified here. It also accepts Retain

Test Plan

• Provision and de-provision volume with Delete reclaim policy and verify that PV & LVMVolume resources should get deleted.
• Provision volume with Retain reclaim policy and trigger deletion of volume and verify that underlying volume should retain.
• Provision & de-provision volume with Retain reclaim policy then try to claim retained volume by creating PVC referencing to retained volume and verify that volume should get provisioned.

Graduation Criteria

All testcases mentioned in Test Plan section need to be automated

Drawbacks

NA

Alternatives

NA