Shrink a cluster

Shrinking a cluster may be required when you need to reduce the cluster's costs, and the performance degradation does not affect your business.

You can shrink the cluster by performing one of the following:

• Remove only some drives from the cluster.

• Remove containers with their allocated drives.

Removing cores, drives, or containers requires deactivating the drives you want to remove. But, if the deactivation leads to insufficient SSD capacity of the currently-provisioned filesystems, the WEKA system does not deactivate the drives, and shrinking the cluster is not allowed.

Before you begin

Run the following command to display a list of all the drives in the cluster with their details, such as UUID and status:

weka cluster drive

Example

root@void-new-1:~# weka cluster drive
DISK ID  UUID                                  HOSTNAME     NODE ID  SIZE      STATUS    LIFETIME % USED  ATTACHMENT  DRIVE STATUS
37       84c4574d-5a46-4644-91aa-df1ceef27ff1  void-new-10  1921     1.09 TiB  ACTIVE    0                OK          OK
45       ecd05959-629c-4319-9d24-f69497c499e3  void-new-19  2401     1.09 TiB  ACTIVE    0                OK          OK
46       4c8af0fa-894b-4096-adb6-17fe98a3a690  void-new-17  2281     1.09 TiB  ACTIVE    0                OK          OK
47       49f684d0-9f2e-4b0a-9153-9aa3570067bd  void-new-18  2341     1.09 TiB  ACTIVE    0                OK          OK
57       7202db57-1f4e-4332-a132-33a47a729d46  void-new-0   1141     1.09 TiB  INACTIVE  0                OK
58       6c2ad35b-a1ff-4b30-9882-0ed3ec166747  void-new-1   1321     1.09 TiB  ACTIVE    0                OK          OK
59       ae8dd40a-9d3d-4154-a26d-3e9643f59e6f  void-new-2   1381     1.09 TiB  ACTIVE    0                OK          OK
60       b96e3c32-3a29-436a-ac35-2e8cf6808e9a  void-new-3   1441     1.09 TiB  ACTIVE    0                OK          OK
61       63ab4d5d-82ed-4248-9ce1-817ce5d7e106  void-new-4   1501     1.09 TiB  ACTIVE    0                OK          OK
62       0f303d2c-5fd0-47e6-9150-0da4afcc454b  void-new-5   1561     1.09 TiB  ACTIVE    0                OK          OK
63       d21f4b3b-1458-4402-8592-06e7ca426d9c  void-new-6   1621     1.09 TiB  ACTIVE    0                OK          OK
64       0c3de49c-b123-4b0b-bd64-e7a90454b41d  void-new-7   1681     1.09 TiB  ACTIVE    0                OK          OK
65       c519e608-ae1d-402e-9f10-da69b227d2c8  void-new-8   1741     1.09 TiB  ACTIVE    0                OK          OK
66       80d53c1d-206e-4021-848b-e52b47bf32fa  void-new-9   1801     1.09 TiB  ACTIVE    0                OK          OK
68       3d669d70-6db2-4a7d-a13b-47ad531f43dd  void-new-11  1861     1.09 TiB  ACTIVE    0                OK          OK
69       ded74ec1-d208-41a9-af2d-eb1c1e81e613  void-new-12  1981     1.09 TiB  ACTIVE    0                OK          OK
70       4451db18-8417-4d4f-b5d0-02bad359b9ff  void-new-13  2041     1.09 TiB  ACTIVE    0                OK          OK
71       019f2b88-c284-4cf4-b384-0a0fde6ea128  void-new-14  2101     1.09 TiB  ACTIVE    0                OK          OK
72       7a315ea8-9f12-4143-b67b-213f2f3f6748  void-new-15  2161     1.09 TiB  ACTIVE    0                OK          OK
73       dce3f522-5672-4964-8db8-383774c11569  void-new-16  2221     1.09 TiB  ACTIVE    0                OK          OK

Remove only some drives from the cluster

Perform the following:

1. Deactivate drives.

2. Remove drives from the cluster.

Deactivate drives

Drive deactivation starts an asynchronous process known as phasing out. It is a gradual redistribution of the data between the remaining drives in the system. On completion, the phased-out drives are in an inactive state. The WEKA cluster does not use inactive drives, but they still appear in the drives list.

To deactivate a drive, run the following command:

weka cluster drive deactivate <uuids>

Parameters

Name	Value
uuids*	Comma-separated drive identifiers.

Running the weka cluster drive command is displayed whether the redistribution is still being performed.

Remove drives from the cluster

Once you remove a drive from the cluster, the drive is not recoverable.

To remove a drive, run the following command:

weka cluster drive remove <uuids>

Parameters

Name	Value
Name	Value
uuids*	Comma-separated drive identifiers.

Remove containers with their allocated drives

Perform the following:

1. Deactivate containers.

2. Remove containers from the cluster.

Deactivate containers

To deactivate containers with their drives, run the following command:

weka cluster container deactivate <container-ids> [--allow-unavailable]

Parameters

Name	Value	Default
container-ids*	Space-separated container identifiers
allow-unavailable	Allow deactivation of an unavailable container. If the container-id value returns, it joins the cluster in an active state.	No

Remove containers from the cluster

Removing containers from the cluster switches them to a stem mode (not part of a cluster), so they can be reallocated to another cluster or purpose.

To remove the container from the cluster, run the following command:

weka cluster container remove <container-id>

Parameters

Name	Value
container-id*	Comma-separated container identifiers.