Scaling in your IBM Db2 Warehouse MPP cluster

You can reduce the capacity of your cluster by removing nodes from your deployment.

Before you begin

The image container is in IBM® Cloud Container Registry. To pull a Db2® Warehouse container image, see Getting container images.

About this task

All currently deployed nodes must be at the same level.

Restriction:

You cannot have fewer than three nodes in your cluster.
You can remove data nodes only. The host that you specified as the head node must retain that designation.

To perform this task, you require root authority.

Procedure

On the head node, stop the Db2 Warehouse services by issuing the following command:
```
docker exec -it Db2wh stop
```
On each node, stop the container by issuing the following command:
```
docker stop Db2wh
```
On each node, remove the Db2 Warehouse container by issuing the following command:
```
docker rm Db2wh
```
In the /mnt/clusterfs/nodes configuration file, remove the entries for the nodes that you no longer want.
Log in to Docker on each node host by using your API key:
```
echo <apikey> | docker login -u iamapikey --password-stdin icr.io
```
where <apikey> is the API key that you created as a prerequisite in Getting container images.

On each node, create and initialize the Db2 Warehouse container by issuing the applicable command:

For a container for POWER® LE hardware:

docker run -d -it --privileged=true --net=host --name=Db2wh -v /mnt/clusterfs:/mnt/bludata0 -v /mnt/clusterfs:/mnt/blumeta0 icr.io/obs/hdm/db2wh_ee:v11.5.6.0-db2wh-ppcle

For a container for z Systems® hardware:

docker run -d -it --privileged=true --net=host --name=Db2wh -v /mnt/clusterfs:/mnt/bludata0 -v /mnt/clusterfs:/mnt/blumeta0 icr.io/obs/hdm/db2wh_ee:v11.5.6.0-db2wh-s390x

For a container for x86 hardware:

docker run -d -it --privileged=true --net=host --name=Db2wh -v /mnt/clusterfs:/mnt/bludata0 -v /mnt/clusterfs:/mnt/blumeta0 icr.io/obs/hdm/db2wh_ee:v11.5.6.0-db2wh-linux

On the node hosts that you removed from the cluster, remove the Db2 Warehouse images. If they remain on the hosts, you cannot re-add them to your cluster later.