Scale Down Cluster · Documentation

You can scale down the IOMesh cluster by removing chunk pods in the Kubernetes worker nodes.

Precautions

You can only delete chunk pods. Deleting meta pods is not supported.
You can only remove one chunk pod at a time.
Each chunk pod is created sequentially and given a unique number by StatefulSet, and you should remove them in reverse creation order. For example, if there are 5 chunk pods iomesh-chunk-0, iomesh-chunk-1, iomesh-chunk-2, iomesh-chunk-3, iomesh-chunk-4, deletion should start with iomesh-chunk-4.

Procedure

The following example reduces the number of chunk pods by removing iomesh-chunk-2 on the node k8s-worker-2.

Run the ip a command on the k8s-worker-2 node to obtain the unique IP within the data CIDR. Assume the IP is 192.168.29.23.
Run the following command. Locate the status.summary.chunkSummary.chunks field and find the ID of chunks whose IP is 192.168.29.23.
```
kubectl get iomesh iomesh -n iomesh-system -o yaml
```
```
chunks:
- id: 2 # The chunk ID.
  ip: 192.168.29.23
```

Get the meta leader pod name.

kubectl get pod -n iomesh-system -l=iomesh.com/meta-leader -o=jsonpath='{.items[0].metadata.name}'

iomesh-meta-0

Access the meta leader pod.

kubectl exec -it iomesh-meta-0 -n iomesh-system -c iomesh-meta bash

Perform chunk unregister. Replace <chunk_id> with the chunk ID obtained from Step 2.

Depending on the size of the data in the chunk, executing this command can take from a few minutes to several hours.
```
/opt/iomesh/iomeshctl chunk unregister <chunk_id>
```
Find chunk in iomesh.yaml, the default configuration file exported during IOMesh installation, and then edit replicaCount.
```
chunk:
  replicaCount: 3 # Reduce the value to 2. 
```

Apply the modification.

helm upgrade --namespace iomesh-system iomesh iomesh/iomesh --values iomesh.yaml

Verify that the number of chunk pods is reduced.

kubectl get pod -n iomesh-system | grep chunk

If successful, you should see output like this:

iomesh-chunk-0                                         3/3     Running   0          5h5m
iomesh-chunk-1                                         3/3     Running   0          5h5m

Run the following command. Then locate the status.summary.chunkSummary.chunks field to verify that the chunk was removed.
```
kubectl get iomesh iomesh -n iomesh-system -o yaml
```