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12.2. Reducing Storage Capacity

Heketi also supports the reduction of storage capacity. You can reduce storage by deleting devices, nodes, and clusters. These requests can only be performed by using the Heketi CLI or the API. For information on using command line API, see Heketi API https://github.com/heketi/heketi/wiki/API.

Note

  • The IDs can be retrieved by executing the heketi-cli topology info command. 
    # heketi-cli topology info
  • The heketidbstorage volume cannot be deleted as it contains the heketi database.

12.2.1. Deleting Volumes

You can delete the volume using the following Heketi CLI command: 
# heketi-cli volume delete <volume_id>
For example: 
heketi-cli volume delete 12b2590191f571be9e896c7a483953c3
Volume 12b2590191f571be9e896c7a483953c3 deleted

12.2.2. Deleting Device

Deleting the device deletes devices from heketi's topology. Devices that have bricks cannot be deleted. You must ensure they are free of bricks by disabling and removing devices.

12.2.2.1. Disabling and Enabling a Device

Disabling devices stops further allocation of bricks onto the device. You can disable devices using the following Heketi CLI command: 
# heketi-cli device disable <device_id>
For example: 
# heketi-cli device disable f53b13b9de1b5125691ee77db8bb47f4
Device f53b13b9de1b5125691ee77db8bb47f4 is now offline
If you want to re-enable the device, execute the following command. Enabling the device allows allocation of bricks onto the device. 
# heketi-cli device enable <device_id>
For example: 
# heketi-cli device enable f53b13b9de1b5125691ee77db8bb47f4
Device f53b13b9de1b5125691ee77db8bb47f4 is now online

12.2.2.2. Removing and Deleting the Device

Removing devices moves existing bricks from the device to other devices. This helps in ensuring the device is free of bricks. A device can be removed only after disabling it.
  1. Remove device using the following command: 
     # heketi-cli device remove <device_id>
    For example: 
    heketi-cli device remove e9ef1d9043ed3898227143add599e1f9
Device e9ef1d9043ed3898227143add599e1f9 is now removed
  2. Delete the device using the following command: 
    # heketi-cli device delete <device_id>
    For example: 
    heketi-cli device delete 56912a57287d07fad0651ba0003cf9aa
Device 56912a57287d07fad0651ba0003cf9aa deleted
    The only way to reuse a deleted device is by adding the device to heketi's topology again.

12.2.2.3. Replacing a Device

Heketi does not allow one-to-one replacement of a device with another. However, in case of a failed device, follow the example below for the sequence of operations that are required to replace a failed device.
  1. Locate the device that has failed using the following command: 
    # heketi-cli topology info
    …
…
...
    Nodes:
Node Id: 8faade64a9c8669de204b66bc083b10d
...
...
…
                Id:a811261864ee190941b17c72809a5001   Name:/dev/vdc            State:online    Size (GiB):499     Used (GiB):281     Free (GiB):218     
                        Bricks:
                                Id:34c14120bef5621f287951bcdfa774fc   Size (GiB):280     Path: /var/lib/heketi/mounts/vg_a811261864ee190941b17c72809a5001/brick_34c14120bef5621f287951bcdfa774fc/brick
…
…
...
    The example below illustrates the sequence of operations that are required to replace a failed device. The example uses device ID a811261864ee190941b17c72809a5001 which belongs to node with id 8faade64a9c8669de204b66bc083b10das.
  2. Add a new device preferably to the same node as the device being replaced. 
    # heketi-cli device add --name /dev/vdd --node 8faade64a9c8669de204b66bc083b10d
Device added successfully
  3. Disable the failed device. 
    # heketi-cli device disable a811261864ee190941b17c72809a5001
Device a811261864ee190941b17c72809a5001 is now offline
  4. Remove the failed device. 
    # heketi-cli device remove a811261864ee190941b17c72809a5001
 Device a811261864ee190941b17c72809a5001 is now removed
    At this stage, the bricks are migrated from the failed device. Heketi chooses a suitable device based on the brick allocation algorithm. As a result, there is a possibility that all the bricks might not be migrated to the new added device.
  5. Delete the failed device. 
    # heketi-cli device delete a811261864ee190941b17c72809a5001
Device a811261864ee190941b17c72809a5001 deleted
  6. Before repeating the above sequence of steps on another device, you must wait for the self-heal operation to complete. You can verify that the self-heal operation completed when the Number of entries value returns a 0 value. 
    # oc rsh <any_gluster_pod_name>
for each in $(gluster volume list) ; do gluster vol heal $each info | grep "Number of entries:" ; done
Number of entries: 0
Number of entries: 0
Number of entries: 0

12.2.3. Deleting Node

Nodes that have devices added to it cannot be deleted. To delete the node, the devices that are associated with the node have to be deleted. Disabling and removing the node ensures all the underlying devices are removed too. Once the node is removed, all the devices in it can be deleted and finally the node can be deleted.

12.2.3.1. Disabling and Enabling a Node

Disabling node stops further allocation of bricks onto all the devices associated to the node. You can disable nodes using the following Heketi CLI command: 
# heketi-cli node disable <node_id>
For example: 
heketi-cli node disable 5f0af88b968ed1f01bf959fe4fe804dc
Node 5f0af88b968ed1f01bf959fe4fe804dc is now offline
If you want to re-enable the node, execute the following command. 
# heketi-cli node enable <node_id>
For example: 
heketi-cli node enable 5f0af88b968ed1f01bf959fe4fe804dc
Node 5f0af88b968ed1f01bf959fe4fe804dc is now online

12.2.3.2. Removing and Deleting the Node

Removing nodes moves existing bricks from all the devices in the node to other devices in the cluster. This helps in ensuring all the device in the node is free of bricks. A device can be removed only after disabling it.
  1. To remove the node execute the following command: 
    # heketi-cli node remove <node_id>
    For example: 
    heketi-cli node remove 5f0af88b968ed1f01bf959fe4fe804dc
Node 5f0af88b968ed1f01bf959fe4fe804dc is now removed
  2. Delete the devices associated with the node by executing the following command as the nodes that have devices associated with it cannot be deleted: 
    # heketi-cli device delete <device_id>
    For example: 
    heketi-cli device delete 56912a57287d07fad0651ba0003cf9aa
Device 56912a57287d07fad0651ba0003cf9aa deleted
    Execute the command for every device on the node.
  3. Delete the node using the following command: 
    # heketi-cli node delete <node_id>
    For example: 
    heketi-cli node delete 5f0af88b968ed1f01bf959fe4fe804dc
Node 5f0af88b968ed1f01bf959fe4fe804dc deleted
    Deleting the node deletes the node from the heketi topology. The only way to reuse a deleted node is by adding the node to heketi's topology again

12.2.3.3. Replacing a Node

Heketi does not allow one-to-one replacement of a node with another. However, in case of a failed node, follow the example below for the sequence of operations that are required to replace a failed node and its respective devices.
  1. Locate the node that has failed using the following command: 
    # heketi-cli topology info

…
…
...
    Nodes:
Node Id: 8faade64a9c8669de204b66bc083b10d
...
...
…
                Id:a811261864ee190941b17c72809a5001   Name:/dev/vdc            State:online    Size (GiB):499     Used (GiB):281     Free (GiB):218     
                        Bricks:
                                Id:34c14120bef5621f287951bcdfa774fc   Size (GiB):280     Path: /var/lib/heketi/mounts/vg_a811261864ee190941b17c72809a5001/brick_34c14120bef5621f287951bcdfa774fc/brick
…
…
...
    The example below illustrates the sequence of operations that are required to replace a failed node. The example uses node ID 8faade64a9c8669de204b66bc083b10d.
  2. Add a new node, preferably that has the same devices as the node being replaced. 
    # heketi-cli node add --zone=1 --cluster=597fceb5d6c876b899e48f599b988f54 --management-host-name=node4.example.com --storage-host-name=192.168.10.104

# heketi-cli device add --name /dev/vdd --node 8faade64a9c8669de204b66bc083b10d

Node and device added successfully
  3. Disable the failed node. 
    # heketi-cli node disable 8faade64a9c8669de204b66bc083b10d
Node 8faade64a9c8669de204b66bc083b10d is now offline
  4. Remove the failed node. 
    # heketi-cli node remove 8faade64a9c8669de204b66bc083b10d
 Node 8faade64a9c8669de204b66bc083b10d is now removed
    At this stage, the bricks are migrated from the failed node. Heketi chooses a suitable device based on the brick allocation algorithm.
  5. Delete the devices associated with the node by executing the following command as the nodes that have devices associated with it cannot be deleted: 
    # heketi-cli device delete <device_id>
    For example: 
    heketi-cli device delete 56912a57287d07fad0651ba0003cf9aa
Device 56912a57287d07fad0651ba0003cf9aa deleted
    Execute the command for every device on the node.
  6. Delete the failed node. 
    # heketi-cli node delete 8faade64a9c8669de204b66bc083b10d
Node 8faade64a9c8669de204b66bc083b10d deleted

12.2.4. Deleting Clusters

You can delete the cluster using the following Heketi CLI command: 
# heketi-cli cluster delete <cluster_id>
For example: 
heketi-cli cluster delete 0e949d91c608d13fd3fc4e96f798a5b1
Cluster 0e949d91c608d13fd3fc4e96f798a5b1 deleted