mirror of https://github.com/ceph/ceph-csi.git synced 2024-11-09 16:00:22 +00:00

Prasanna Kumar Kalever 2945f7b669 cleanup: stick to standards when using dollar-sign in md

MD014 - Dollar signs used before commands without showing output
The dollar signs are unnecessary, it is easier to copy and paste and
less noisy if the dollar signs are omitted. Especially when the
command doesn't list the output, but if the command follows output
we can use `$ ` (dollar+space) mainly to differentiate between
command and its ouput.

scenario 1: when command doesn't follow output
```console
cd ~/work
```

scenario 2: when command follow output (use dollar+space)
```console
$ ls ~/work
file1 file2 dir1 dir2 ...
```

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>

2020-11-11 13:18:05 +00:00

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Steps and RBD CLI commands for RBD snapshot and clone operations

Steps and RBD CLI commands for RBD snapshot and clone operations

This document outlines the command used to create RBD snapshot, delete RBD snapshot, Restore RBD snapshot and Create new RBD image from existing RBD image.

Create a snapshot from PVC

Refer snapshot for more information realted to Volume cloning in kubernetes.

steps to create a snapshot

Check if the parent image has more snapshots than the configured value, if it has more snapshot, add tasks to flatten all the temporary cloned images and return ResourceExhausted error message
Create a temporary snapshot from the parent image
Clone a new image from a temporary snapshot with options --rbd-default-clone-format 2 --image-feature layering,deep-flatten
Delete temporary snapshot created
Check the image chain depth, if the softlimit is reached add a task to flatten the cloned image and return success. If the depth is reached hardlimit add a task flatten the cloned image and return snapshot status ready as false

RBD CLI commands to create snapshot

rbd snap ls <RBD image for src k8s volume> --all

// If the parent has more snapshots than the configured `maxsnapshotsonimage`
// add backgound tasks to flatten the temporary cloned images (temporary cloned
// image names will be same as snapshot names)
ceph rbd task add flatten <RBD image for temporary snap images>

rbd snap create <RBD image for src k8s volume>@<random snap name>
rbd clone --rbd-default-clone-format 2 --image-feature
    layering,deep-flatten <RBD image for src k8s volume>@<random snap>
    <RBD image for temporary snap image>
rbd snap rm <RBD image for src k8s volume>@<random snap name>
rbd snap create <RBD image for temporary snap image>@<random snap name>

// check the depth, if the depth is greater than configured hardlimit add a
// task to flatten the cloned image, return snapshot status ready as `false`,
// if the depth is greater than softlimit add a task to flatten the image
// and return success
ceph rbd task add flatten <RBD image for temporary snap image>

Create PVC from a snapshot (datasource snapshot)

steps to create a pvc from snapshot

Check the depth(n) of the cloned image if n>=(hardlimit -2), add task to flatten the image and return ABORT (to avoid image leak)
Clone a new image from the snapshot with user-provided options

RBD CLI commands to create clone from snapshot

// check the depth, if the depth is greater than configured (hardlimit)
// Add a task to value flatten the cloned image
ceph rbd task add flatten <RBD image for temporary snap image>

rbd clone --rbd-default-clone-format 2 --image-feature <k8s dst vol config>
    <RBD image for temporary snap image>@<random snap name>
    <RBD image for k8s dst vol>
// check the depth,if the depth is greater than configured hardlimit add a task
// to flatten the cloned image return ABORT error, if the depth is greater than
// softlimit add a task to flatten the image and return success
ceph rbd task add flatten <RBD image for k8s dst vol>

Delete a snapshot

steps to delete a snapshot

Delete temporary snapshot on temporary cloned image
Move the temporary cloned image to trash
Add task to remove the image from trash

RBD CLI commands to delete a snapshot

rbd snap create <RBD image for temporary snap image>@<random snap name>
rbd trash mv <RBD image for temporary snap image>
ceph rbd task trash remove <RBD image for temporary snap image ID>

Delete a Volume (PVC)

With earlier implementation to delete the image we used to add a task to remove the image. With new changes this cannot be done as the image may contains snapshots or linking, so we will be following below steps to delete an image(this will be applicable for both normal image and cloned image)

steps to delete a volume

Move the rbd image to trash
Add task to remove the image from trash

RBD CLI commands to delete a volume

1) rbd trash mv <image>
2) ceph rbd task trash remove <image>

Volume cloning (datasource pvc)

Refer volume-cloning for more information realted to Volume cloning in kubernetes.

steps to create a Volume from Volume

Check the depth(n) of the cloned image if n>=((hard limit) -2), add task to flatten the image and return ABORT (to avoid image leak)
Create snapshot of rbd image
Clone the snapshot (temp clone)
Delete the snapshot
Snapshot the temp clone
Clone the snapshot (final clone)
Delete the snapshot

RBD CLI commands to create a Volume from Volume

// check the image depth of the parent image if flatten required add a
// task to flatten image and return ABORT to avoid leak(same hardlimit and
// softlimit check will be done)
ceph rbd task add flatten <RBD image for src k8s volume>

rbd snap create <RBD image for src k8s volume>@<random snap name>
rbd clone --rbd-default-clone-format 2 --image-feature
    layering,deep-flatten <RBD image for src k8s volume>@<random snap>
    <RBD image for temporary snap image>
rbd snap rm <RBD image for src k8s volume>@<random snap name>
rbd snap create <RBD image for temporary snap image>@<random snap name>
rbd clone --rbd-default-clone-format 2 --image-feature <k8s dst vol config>
    <RBD image for temporary snap image>@<random snap name>
    <RBD image for k8s dst vol>
rbd snap rm <RBD image for src k8s volume>@<random snap name>

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