rawfile-localpv/README.md
Mehran Kholdi d1c0d49cf0 Support online volume expansion
Summary:
Online volume expansion is a 2 phase process:

1. The backing storage, in this case the raw file, needs to be resized. (i.e. `truncate -s`)
2. The node should be notified, so that it can both refresh its device capacity (i.e. `losetup -c`) and resize the filesystem (`resize2fs`) accordingly.

Although in our case both steps could be performed on the node itself, for the sake of following the semantics of how volume expansion works, we perform step 1 from the controller, and step 2 from the node.

Also, the `external-resizer` component is added which watches for PVC size updates, and notifies the CSI controller about it.

Test Plan:
Setup:
- Deploy
- Create a rawfile-backed pvc, and attach a Deployment to it
- Keep an eye on `rawfile` pod logs in `kube-system` namespace to see if any errors pop out during all scenarios

Scenario 1:
- Increase the size of the pvc
- Exec into the pod and verify that the volume is resized indeed (using `df`)

Scenario 2:
- Decrease deployment's replica to 0
- Increase the size of the pvc. Wait for a couple of minutes.
- Increase deployment's replica to 1
- Exec into the pod and verify that the volume is resized indeed.

Reviewers: bghadiri, mhyousefi, h.marvi, sina_rad

Reviewed By: bghadiri, mhyousefi, sina_rad

Differential Revision: https://phab.hamravesh.ir/D817
2020-06-14 03:35:17 +04:30

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Markdown

RawFilePV
===
Kubernetes LocalPVs on Steroids
Install
---
`helm install -n kube-system rawfile-csi ./deploy/charts/rawfile-csi/`
Usage
---
Create a `StorageClass` with your desired options:
```
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: my-sc
provisioner: rawfile.hamravesh.com
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true
```
Features
---
- [x] Direct I/O: Near-zero disk performance overhead
- [x] Dynamic provisioning
- [x] Enforced volume size limit
- [x] Thin provisioned
- [x] Access Modes
- [x] ReadWriteOnce
- ~~ReadOnlyMany~~
- ~~ReadWriteMany~~
- [ ] Volume modes
- [x] `Filesystem` mode
- [ ] `Block` mode
- [x] Volume metrics
- [ ] Supports fsTypes
- [x] Online expansion: If fs supports it (e.g. ext4, btrfs)
- [ ] Online shrinking: If fs supports it (e.g. btrfs)
- [ ] Offline expansion/shrinking
- [ ] Ephemeral inline volume
- [ ] Snapshots: If the fs supports it (e.g. btrfs)