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Cloning block volumes

Objective: Clone a Virtual Server block volume between storage classes, or regions.
Overview: This guide details using the clone_block_volume function from the Kubernetes Cloud repository to clone between two example datacenter regions.

note

This guide requires kubectl and a valid access token. View Getting Started for more details.

Volume Cloning​

Storage Classes​

Storage on CoreWeave Cloud is delineated by storage classes, in the notation of <storage type block|shared>-<storage medium hdd|nvme>-<region ord1|las1|etc>. For example:

  • block-nvme-ewr1
  • block-nvme-las1
  • block-nvme-lga1
  • block-nvme-ord1

CSI Volume Cloning allows an existing volume to be duplicated:

Cloning via CLI within the same Storage Class​

Cloning a block volume within the same storage class is easily done using our PVC cloning script, or with a simple PVC manifest:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: destination-pvc
spec:
  accessModes:
  - ReadWriteOnce
  storageClassName: block-nvme-ord1
  volumeMode: Block
  resources:
    requests:
      storage: 1234Gi
  dataSource:
    kind: PersistentVolumeClaim
    name: source-pvc

Cloning via Web UI within the same Storage Class​

Cloning within the same storage class can also be accomplished via the CoreWeave Cloud Storage UI:

Cloning via CLI between Storage Classes​

Cloning a block volume between storage classes, as done when cloning between regions, requires data within the volume to be manually duplicated, as it cannot be zero-copied.

To automate the process of cloning a Virtual Server root disk block volume, we provide a block volume cloning script. This script creates a Kubernetes Job along with a new volume in the destination region, and uses dd to clone between source as destination.

First, we identify the Virtual Server root disk volume we'd like to clone, located on CoreWeave's GitHub.

$ kubectl get pvc vs-example
NAME         STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS      AGE
vs-example   Bound    pvc-78d4950a-e1ba-476f-815e-b9c32e9c8b27   40Gi       RWO            block-nvme-ewr1   3m11s

Ensure it's not running:

$ kubectl get vs vs-example
NAME         STATUS                 REASON                 STARTED   INTERNAL IP   EXTERNAL IP
vs-example   VirtualServerStopped   VirtualServerStopped   False

Download and source the script:

$ curl https://raw.githubusercontent.com/coreweave/kubernetes-cloud/master/virtual-server/clone_block_volume.sh -o ~/clone_block_volume.sh
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  4109  100  4109    0     0  27211      0 --:--:-- --:--:-- --:--:-- 27211

$ source ~/clone_block_volume.sh

Initiate a clone:

$ clone_block_volume  --source vs-example --destination vs-example --region lga1
persistentvolumeclaim/vs-example-lga1 created
job.batch/clone-vs-example-lga1 created
No resources found in namespace.
pod/clone-vs-example-lga1-rn55n condition met
job.batch/clone-vs-example-lga1 condition met
42945478656 bytes (43 GB, 40 GiB) copied, 54 s, 795 MB/s
40960+0 records in
40960+0 records out
42949672960 bytes (43 GB, 40 GiB) copied, 54.0091 s, 795 MB/s
job.batch "clone-vs-example-lga1" deleted

Script Workflow​

In the clone example above, the following actions were performed:

  • A new PVC in the destination namespace was created - vs-example-lga1
  • A cloning job was created - clone-vs-example-lga1
  • The script pauses until a worker pod is spun up - clone-vs-example-lga1-rn55n
  • The script pauses until the job reports a completed status
  • Stats from the copy job are printed
  • The Job (and its worker pod) are cleaned up and deleted

Script Arguments​

  • --source
    • Name of the root disk volume being cloned
  • --destination
    • Desired name of new volume
    • Region will always be appended as -region, e.g new-vol-lga1
  • --region
    • Name of destination region
    • Storage class is automatically derived as block-nvme-region