Shrink a Cluster
This page describes the procedures involved in the shrinking of a cluster, which may be required when it is necessary to reallocate cluster hardware.
Cluster shrinking can involve either the removal of some of the assigned SSDs or the removal of hosts from the system. The following operations are available:
- 1.List all the drives and their states, to receive a view of currently-allocated resources and their status.
- 2.Deactivate drives as the first step before removing a host.
- 3.Remove a subset of SSD drives allocated for the cluster.
- 4.Deactivate hosts, which can be used after deactivating drives in preparation for the removal of the host.
- 5.Remove hosts to complete the cluster shrinking.
weka cluster drive
Use this command to display a list of all the drives in the cluster and their status.
weka cluster drive deactivate
Running this deactivation command will redistribute the stored data on the remaining drives and can be performed on multiple drives.
Drive deactivation starts an asynchronous process known as phasing out, which is a gradual redistribution of the data between the remaining drives in the system. On completion, the phased-out drive is in an inactive state, i.e., not in use by the Weka system, but still appearing in the list of drives.
To deactivate a drive, run the following command:
weka cluster drive deactivate <uuids>
weka cluster drive remove
This command is used to completely remove a drive from the cluster. After removal, the drive will not be recoverable.
To remove a drive, run the following command:
weka cluster drive remove <uuids>
weka cluster host deactivate
To deactivate an entire host, run the following command:
weka cluster host deactivate <host-ids> [--allow-unavailable]
weka cluster host remove
Running this command will eliminate the host from the cluster, i.e., the host will switch to the stem mode after the removal, at which point it can be reallocated either to another cluster or purpose.
To remove the host from the cluster, run the following command:
weka cluster host remove <host-id>