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Scaling storage

Red Hat OpenShift Container Storage 4.7

Horizontal and vertical scaling options

Red Hat Storage Documentation Team

Abstract

This document explains scaling options for Red Hat OpenShift Container Storage.

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Preface

To scale the storage capacity of OpenShift Container Storage in internal mode, you can do either of the following:

  • Scale up storage nodes - Add storage capacity to the existing Red Hat OpenShift Container Storage worker nodes
  • Scale out storage nodes - Add new worker nodes containing storage capacity

For scaling your storage in external mode, see Red Hat Ceph Storage documentation.

Chapter 1. Requirements for scaling storage nodes

Before you proceed to scale the storage nodes, refer to the following sections to understand the node requirements for your specific Red Hat OpenShift Container Storage instance:

Important

Always ensure that you have plenty of storage capacity.

If storage ever fills completely, it is not possible to add capacity or delete or migrate content away from the storage to free up space. Completely full storage is very difficult to recover.

Capacity alerts are issued when cluster storage capacity reaches 75% (near-full) and 85% (full) of total capacity. Always address capacity warnings promptly, and review your storage regularly to ensure that you do not run out of storage space.

If you do run out of storage space completely, contact Red Hat Customer Support.

1.1. Supported Deployments for Red Hat OpenShift Container Storage

  • User-provisioned infrastructure:

    • Amazon Web Services (AWS)
    • VMware
    • Bare metal
    • IBM Power Systems
    • IBM Z or LinuxONE

  • Installer-provisioned infrastructure:

    • Amazon Web Services (AWS)
    • Microsoft Azure
    • VMware
    • Red Hat Virtualization

Chapter 2. Scaling up storage capacity

Depending on the type of your deployment, you can choose one of the following procedures to scale up storage capacity.

If you want to scale using a storage class other than the one provisioned during deployment, you must also define an additional storage class before you scale. See Creating a storage class for details.

Note

OpenShift Container Storage does not support heterogeneous OSD sizes.

2.1. Creating a Storage Class

You can define a new storage class to dynamically provision storage from an existing provider.

Prerequisites

  • Administrator access to OpenShift web console.

Procedure

  1. Log in to OpenShift Web Console.
  2. Click Storage → Storage Classes.
  3. Click Create Storage Class.
  4. Enter the storage class Name and Description.
  5. Select the required Reclaim Policy and Provisioner.
  6. Click Create to create the Storage Class.

Verification steps

  • Click Storage → Storage Classes and verify that you can see the new storage class.

2.2. Scaling up storage by adding capacity to your OpenShift Container Storage nodes

Use this procedure to add storage capacity and performance to your configured Red Hat OpenShift Container Storage worker nodes on the following infrastructures:

  • AWS
  • VMware vSphere
  • Red Hat Virtualization
  • Microsoft Azure

Prerequisites

  • A running OpenShift Container Storage Platform.
  • Administrative privileges on the OpenShift Web Console.
  • To scale using a storage class other than the one provisioned during deployment, first define an additional storage class. See Creating a storage class for details.

Procedure

  1. Log in to the OpenShift Web Console.
  2. Click on Operators → Installed Operators.
  3. Click OpenShift Container Storage Operator.
  4. Click Storage Cluster tab.
  5. The visible list should have only one item. Click (⋮) on the far right to extend the options menu.
  6. Select Add Capacity from the options menu.

  7. Select the Storage Class.

    Set the storage class to gp2 on AWS, thin on VMware, or ovirt-csi-sc on Red Hat Virtualization, or managed_premium on Microsoft Azure if you are using the default storage class generated during deployment. If you have created other storage classes, select whichever is appropriate.

    Important

    Using storage classes other than the default for your provider is a Technology Preview feature.

    Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

    For more information, see Technology Preview Features Support Scope.

    The Raw Capacity field shows the size set during storage class creation. The total amount of storage consumed is three times this amount, because OpenShift Container Storage uses a replica count of 3.

  8. Click Add and wait for the cluster state to change to Ready.

Verification steps

  • Navigate to Overview → Persistent Storage tab, then check the Raw Capacity breakdown card.

    Note that the capacity increases based on your selections.

    Note

    The raw capacity does not take replication into account and shows the full capacity.

  • Verify that the new OSDs and their corresponding new PVCs are created.

    • To view the state of the newly created OSDs:

      1. Click Workloads → Pods from the OpenShift Web Console.
      2. Select openshift-storage from the Project drop-down list.

    • To view the state of the PVCs:

      1. Click Storage → Persistent Volume Claims from the OpenShift Web Console.
      2. Select openshift-storage from the Project drop-down list.

  • (Optional) If cluster-wide encryption is enabled on the cluster, verify that the new OSD devices are encrypted.

    1. Identify the node(s) where the new OSD pod(s) are running. 

      $ oc get -o=custom-columns=NODE:.spec.nodeName pod/<OSD pod name>

      For example: 

      oc get -o=custom-columns=NODE:.spec.nodeName pod/rook-ceph-osd-0-544db49d7f-qrgqm

    2. For each of the nodes identified in previous step, do the following:

      1. Create a debug pod and open a chroot environment for the selected host(s). 

        $ oc debug node/<node name>
$ chroot /host

      2. Run “lsblk” and check for the “crypt” keyword beside the ocs-deviceset name(s) 

        $ lsblk
Important

Cluster reduction is not currently supported, regardless of whether reduction would be done by removing nodes or OSDs.

2.3. Scaling up storage by adding capacity to your OpenShift Container Storage nodes using local storage devices

Use this procedure to add storage capacity (additional storage devices) to your configured local storage based OpenShift Container Storage worker nodes on the following infrastructures:

  • Bare metal
  • VMware
  • Red Hat Virtualization
Important

Scaling up storage on Amazon EC2 I3 is a Technology Preview feature. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

Note

For Amazon EC2 I3 infrastructure, adding nodes is the only option for adding capacity, as deployment is done using both the available NVMe devices.

Prerequisites

Procedure

To add capacity, you can either use a storage class that you provisioned during the deployment or any other storage class that matches the filter.

  1. On the OpenShift web console, click on Operators → Installed Operators.
  2. Click OpenShift Container Storage Operator.
  3. Click Storage Cluster tab.
  4. The visible list should have only one item. Click (⋮) on the far right to extend the options menu.
  5. Select Add Capacity from the options menu.
  6. Select the Storage Class for which you added disks or the new storage class depending on your requirement. Available Capacity displayed is based on the local disks available in storage class.

  7. Click Add.

    You might need to wait a couple of minutes for the storage cluster to reach Ready state.

Verification steps

  • Navigate to Overview → Persistent Storage tab, then check the Raw Capacity breakdown card.

    Note that the capacity increases based on your selections.

    Note

    The raw capacity does not take replication into account and shows the full capacity.

  • Verify that the new OSDs and their corresponding new PVCs are created.

    • To view the state of the newly created OSDs:

      1. Click Workloads → Pods from the OpenShift Web Console.
      2. Select openshift-storage from the Project drop-down list.

    • To view the state of the PVCs:

      1. Click Storage → Persistent Volume Claims from the OpenShift Web Console.
      2. Select openshift-storage from the Project drop-down list.

  • (Optional) If cluster-wide encryption is enabled on the cluster, verify that the new OSD devices are encrypted.

    1. Identify the node(s) where the new OSD pod(s) are running. 

      $ oc get -o=custom-columns=NODE:.spec.nodeName pod/<OSD pod name>

      For example: 

      oc get -o=custom-columns=NODE:.spec.nodeName pod/rook-ceph-osd-0-544db49d7f-qrgqm

    2. For each of the nodes identified in previous step, do the following:

      1. Create a debug pod and open a chroot environment for the selected host(s). 

        $ oc debug node/<node name>
$ chroot /host

      2. Run “lsblk” and check for the “crypt” keyword beside the ocs-deviceset name(s) 

        $ lsblk
Important

OpenShift Container Storage does not support cluster reduction either by reducing OSDs or reducing nodes.

2.4. Scaling up storage by adding capacity to your OpenShift Container Storage nodes on IBM Z or LinuxONE infrastructure

Use this procedure to add storage capacity and performance to your configured Red Hat OpenShift Container Storage worker nodes.

Prerequisites

  • A running OpenShift Container Storage Platform.
  • Administrative privileges on the OpenShift Web Console.
  • To scale using a storage class other than the one provisioned during deployment, first define an additional storage class. See Creating a storage class for details.

Procedure

  1. Add additional hardware resources with zFCP disks

    1. List all the disks with the following command. 

      $ lszdev

      Example output: 

      TYPE         ID                                              ON   PERS  NAMES
zfcp-host    0.0.8204                                        yes  yes
zfcp-lun     0.0.8204:0x102107630b1b5060:0x4001402900000000  yes  no    sda sg0
zfcp-lun     0.0.8204:0x500407630c0b50a4:0x3002b03000000000  yes  yes   sdb sg1
qeth         0.0.bdd0:0.0.bdd1:0.0.bdd2                      yes  no    encbdd0
generic-ccw  0.0.0009                                        yes  no

      A SCSI disk is represented as a zfcp-lun with the structure <device-id>:<wwpn>:<lun-id> in the ID section. The first disk is used for the operating system. The device id for the new disk can be the same.

    2. Append a new SCSI disk with the following command. 

      $ chzdev -e 0.0.8204:0x400506630b1b50a4:0x3001301a00000000
      Note

      The device ID for the new disk must be the same as the disk to be replaced. The new disk is identified with its WWPN and LUN ID.

    3. List all the FCP devices to verify the new disk is configured. 

      $ lszdev zfcp-lun
TYPE         ID                                              ON   PERS  NAMES
zfcp-lun     0.0.8204:0x102107630b1b5060:0x4001402900000000 yes  no    sda sg0
zfcp-lun     0.0.8204:0x500507630b1b50a4:0x4001302a00000000  yes  yes   sdb sg1
zfcp-lun     0.0.8204:0x400506630b1b50a4:0x3001301a00000000  yes  yes   sdc sg2
  2. Navigate to the OpenShift Web Console.
  3. Click Operators on the left navigation bar.
  4. Select Installed Operators.
  5. In the window, click OpenShift Container Storage Operator:
  6. In the top navigation bar, scroll right and click Storage Cluster tab.
  7. Click (⋮) next to the visible list to extend the options menu.

  8. Select Add Capacity from the options menu.

    The Raw Capacity field shows the size set during storage class creation. The total amount of storage consumed is three times this amount, because OpenShift Container Storage uses a replica count of 3.

  9. Click Add and wait for the cluster state to change to Ready.

Verification steps

  1. Navigate to Overview → Persistent Storage tab, then check the Capacity breakdown card.

    Note that the capacity increases based on your selections.

    Note

    The raw capacity does not take replication into account and shows the full capacity.

Important

Cluster reduction is not currently supported, regardless of whether reduction would be done by removing nodes or OSDs.

2.5. Scaling up storage by adding capacity to your OpenShift Container Storage nodes on IBM Power Systems infrastructure using local storage devices

Use this procedure to add storage capacity (additional storage devices) to your configured local storage based OpenShift Container Storage worker nodes on IBM Power Systems infrastructures.

Prerequisites

  • You must be logged into OpenShift Container Platform (RHOCP) cluster.

  • You must have installed local storage operator. Use the following procedures, see

  • You must have three OpenShift Container Platform worker nodes with the same storage type and size attached to each node (for example, 0.5TB SSD) as the original OpenShift Container Storage StorageCluster was created with.

Procedure

  1. To add storage capacity to OpenShift Container Platform nodes with OpenShift Container Storage installed, you need to

    1. Add a new disk that is, minimum of one device per worker node in your Openshift Container Platform (RHOCP) cluster.

    2. Check if the new disk is added to the node by running lsblk inside node. 

      $ oc debug node/worker-0
$lsblk

      Example output: 

      Creating debug namespace/openshift-debug-node-ggrqr ...
Starting pod/worker-2-debug ...
To use host binaries, run `chroot /host`
Pod IP: 192.168.88.23
If you don't see a command prompt, try pressing enter.
sh-4.4# chroot /host
sh-4.4# lsblk
NAME                         MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
loop0                          7:0    0  256G  0 loop
vda                          252:0    0   40G  0 disk
|-vda1                       252:1    0    4M  0 part
|-vda2                       252:2    0  384M  0 part /boot
`-vda4                       252:4    0 39.6G  0 part
  `-coreos-luks-root-nocrypt 253:0    0 39.6G  0 dm   /sysroot
vdb                          252:16   0  512B  1 disk
vdc                          252:32   0  256G  0 disk
vdd                          252:48   0  256G  0 disk
sh-4.4#
sh-4.4#
Removing debug pod ...
Removing debug namespace/openshift-debug-node-ggrqr ...
    3. Newly added disk will automatically gets discovered by LocalVolumeSet.

  2. Display the newly created PVs with storageclass name used in localVolumeSet CR. 

    $ oc get pv | grep localblock | grep Available

    Example output: 

    local-pv-290020c2   256Gi   RWO     Delete  Available   localblock      2m35s
local-pv-7702952c   256Gi   RWO     Delete  Available   localblock      2m27s
local-pv-a7a567d    256Gi   RWO     Delete  Available   localblock      2m22s
...

    There are three more available PVs of same size which will be used for new OSDs.

  3. Navigate to the OpenShift Web Console.
  4. Click on Operators on the left navigation bar.
  5. Select Installed Operators.
  6. In the window, click OpenShift Container Storage Operator:
  7. In the top navigation bar, scroll right and click Storage Cluster tab.
  8. The visible list should have only one item. Click (⋮) on the far right to extend the options menu.

  9. Select Add Capacity from the options menu.

    From this dialog box, set the Storage Class name to the name used in the localVolumeset CR. Available Capacity displayed is based on the local disks available in storage class.

  10. Once you are done with your setting, click Add. You might need to wait a couple of minutes for the storage cluster to reach Ready state.

  11. Verify that the new OSDs and their corresponding new PVCs are created. 

    $ oc get -n openshift-storage pods -l app=rook-ceph-osd

    Example output: 

    NAME                               READY   STATUS    RESTARTS   AGE
rook-ceph-osd-0-6f8655ff7b-gj226   1/1     Running   0          1h
rook-ceph-osd-1-6c66d77f65-cfgfq   1/1     Running   0          1h
rook-ceph-osd-2-69f6b4c597-mtsdv   1/1     Running   0          1h
rook-ceph-osd-3-c784bdbd4-w4cmj    1/1     Running   0          5m
rook-ceph-osd-4-6d99845f5b-k7f8n   1/1     Running   0          5m
rook-ceph-osd-5-fdd9897c9-r9mgb    1/1     Running   0          5m

    In the above example, osd-3, osd-4, and osd-5 are the newly added pods to the OpenShift Container Storage cluster. 

    $ oc get pvc -n openshift-storage |grep localblock

    Example output: 

    ocs-deviceset-localblock-0-data-0-sfsgf   Bound    local-pv-8137c873      256Gi     RWO    localblock  1h
ocs-deviceset-localblock-0-data-1-qhs9m   Bound    local-pv-290020c2      256Gi     RWO    localblock  10m
ocs-deviceset-localblock-1-data-0-499r2   Bound    local-pv-ec7f2b80      256Gi     RWO    localblock  1h
ocs-deviceset-localblock-1-data-1-p9rth   Bound    local-pv-a7a567d       256Gi     RWO    localblock  10m
ocs-deviceset-localblock-2-data-0-8pzjr   Bound    local-pv-1e31f771      256Gi     RWO    localblock  1h
ocs-deviceset-localblock-2-data-1-7zwwn   Bound    local-pv-7702952c      256Gi     RWO    localblock  10m

    In the above example, we see three new PVCs are created.

Verification steps

  1. Navigate to Overview → Persistent Storage tab, then check the Capacity breakdown card.

    Note that the capacity increases based on your selections.

    Note

    The raw capacity does not take replication into account and shows the full capacity.

Important

OpenShift Container Storage does not support cluster reduction either by reducing OSDs or reducing nodes.

Chapter 3. Scaling out storage capacity

To scale out storage capacity, you need to perform the following steps:

  • Add a new node
  • Verify that the new node is added successfully
  • Scale up the storage capacity
Note

OpenShift Container Storage does not support heterogeneous OSD sizes.

3.1. Adding a node

You can add nodes to increase the storage capacity when existing worker nodes are already running at their maximum supported OSDs, which is increment of 3 OSDs of the capacity selected during initial configuration.

Depending on the type of your deployment, you can choose one of the following procedures to add a storage node:

3.1.1. Adding a node on an installer-provisioned infrastructure

Use this proecdure to add a node on the following installer provisioned infrastructures:

  • AWS
  • Azure
  • Red Hat Virtualization

Prerequisites

  • You must be logged into OpenShift Container Platform (RHOCP) cluster.

Procedure

  1. Navigate to Compute → Machine Sets.
  2. On the machine set where you want to add nodes, select Edit Machine Count.
  3. Add the amount of nodes, and click Save.
  4. Click Compute → Nodes and confirm if the new node is in Ready state.

  5. Apply the OpenShift Container Storage label to the new node.

    1. For the new node, Action menu (⋮) → Edit Labels.
    2. Add cluster.ocs.openshift.io/openshift-storage and click Save.
Note

It is recommended to add 3 nodes, one each in different zones. You must add 3 nodes and perform this procedure for all of them.

Verification steps

3.1.2. Adding a node on an user-provisioned infrastructure

Use this procedure to add a node on an AWS or VMware user-provisioned infrastructure.

Prerequisites

  • You must be logged into OpenShift Container Platform (RHOCP) cluster.

Procedure

  1. Depending on whether you are adding a node on an AWS user provisioned infrastructure or a VMware user-provisioned infrastructure, perform the following steps:

    • For AWS

      1. Create a new AWS machine instance with the required infrastructure. See Platform requirements.
      2. Create a new OpenShift Container Platform node using the new AWS machine instance.

    • For VMware:

      1. Create a new VM on vSphere with the required infrastructure. See Platform requirements.
      2. Create a new OpenShift Container Platform worker node using the new VM.

  2. Check for certificate signing requests (CSRs) related to OpenShift Container Storage that are in Pending state: 

    $ oc get csr

  3. Approve all required OpenShift Container Storage CSRs for the new node: 

    $ oc adm certificate approve <Certificate_Name>
  4. Click Compute → Nodes, confirm if the new node is in Ready state.

  5. Apply the OpenShift Container Storage label to the new node using any one of the following:

    From User interface
    1. For the new node, click Action Menu (⋮) → Edit Labels
    2. Add cluster.ocs.openshift.io/openshift-storage and click Save.
    From Command line interface

    • Execute the following command to apply the OpenShift Container Storage label to the new node: 

      $ oc label node <new_node_name> cluster.ocs.openshift.io/openshift-storage=""
      Note

      It is recommended to add 3 nodes, one each in different zones. You must add 3 nodes and perform this procedure for all of them.

Verification steps

3.1.3. Adding a node using a local storage device

Use this procedure to add a node on the following:

  • Bare metal
  • IBM Power Systems
  • IBM Z or LinuxONE
  • Amazon EC2
  • VMware
  • Red Hat Virtualization
Important

Scaling storage nodes for Amazon EC2 infrastructure is a Technology Preview feature. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

Prerequisites

  • You must be logged into the OpenShift Container Platform (RHOCP) cluster.
  • You must have three OpenShift Container Platform worker nodes with the same storage type and size attached to each node (for example, 2TB SSD or 2TB NVMe drive) as the original OpenShift Container Storage StorageCluster was created with.
  • If you have upgraded from a previous version of OpenShift Container Storage and have not already created a LocalVolumeDiscovery object, do so now by following the procedure described in Post-update configuration changes for clusters backed by local storage.
  • If you have upgraded from a previous version of OpenShift Container Storage and have not already created a LocalVolumeSet object to enable automatic provisioning of devices, do so now by following the procedure described in Post-update configuration changes for clusters backed by local storage.

Procedure

  1. Depending on whether you are adding a node on bare metal, IBM Power Systems, IBM Z or LinuxONE, Amazon EC2, VMware infrastructure, or Red Hat Virtualization platform, perform the following steps:

    • For Amazon EC2

      1. Create a new Amazon EC2 I3 machine instance with the required infrastructure. See Creating a MachineSet in AWS and Platform requirements.
      2. Create a new OpenShift Container Platform node using the new Amazon EC2 I3 machine instance.

    • For VMware:

      1. Create a new VM on vSphere with the required infrastructure. See Platform requirements.
      2. Create a new OpenShift Container Platform worker node using the new VM.

    • For Red Hat Virtualization:

      1. Create a new VM on Red Hat Virtualization with the required infrastructure. See Platform requirements.
      2. Create a new OpenShift Container Platform worker node using the new VM.

    • For bare metal:

      1. Get a new bare metal machine with the required infrastructure. See Platform requirements.
      2. Create a new OpenShift Container Platform node using the new bare metal machine.

    • For IBM Power Systems:

      1. Get a new IBM Power machine with the required infrastructure. See Platform requirements.
      2. Create a new OpenShift Container Platform node using the new IBM Power machine.

    • For IBM Z or LinuxONE:

      1. Get a new IBM Z or LinuxONE machine with the required infrastructure. See Platform requirements.
      2. Create a new OpenShift Container Platform node using the new IBM Z or LinuxONE machine.

  2. Check for certificate signing requests (CSRs) related to OpenShift Container Storage that are in Pending state: 

    $ oc get csr

  3. Approve all required OpenShift Container Storage CSRs for the new node: 

    $ oc adm certificate approve <Certificate_Name>
  4. Click Compute → Nodes, confirm if the new node is in Ready state.

  5. Apply the OpenShift Container Storage label to the new node using any one of the following:

    From User interface
    1. For the new node, click Action Menu (⋮) → Edit Labels
    2. Add cluster.ocs.openshift.io/openshift-storage and click Save.
    From Command line interface

    • Execute the following command to apply the OpenShift Container Storage label to the new node: 

      $ oc label node <new_node_name> cluster.ocs.openshift.io/openshift-storage=""

  6. Click Operators → Installed Operators from the OpenShift Web Console.

    From the Project drop-down list, make sure to select the project where the Local Storage Operator is installed.

  7. Click on Local Storage.
  8. Click the Local Volume Discovery tab.
  9. Beside the LocalVolumeDiscovery, click Action menu (⋮) → Edit Local Volume Discovery.
  10. In the YAML, add the hostname of the new node in the values field under the node selector.
  11. Click Save.
  12. Click the Local Volume Sets tab.
  13. Beside the LocalVolumeSet, click Action menu (⋮) → Edit Local Volume Set.

  14. In the YAML, add the hostname of the new node in the values field under the node selector.

    Figure 3.1. YAML showing the addition of new hostnames

    Screenshot of YAML showing the addition of new hostnames.
  15. Click Save.
Note

It is recommended to add 3 nodes, one each in different zones. You must add 3 nodes and perform this procedure for all of them.

Verification steps

3.1.4. Verifying the addition of a new node

  1. Execute the following command and verify that the new node is present in the output: 

    $ oc get nodes --show-labels | grep cluster.ocs.openshift.io/openshift-storage= |cut -d' ' -f1

  2. Click Workloads → Pods, confirm that at least the following pods on the new node are in Running state:

    • csi-cephfsplugin-*
    • csi-rbdplugin-*

3.2. Adding capacity to a newly added node

To add capacity to a newly added node, either use the Add Capacity option to expand the storage cluster with 3 OSDs or use the new flexible scaling feature that allows you to expand the storage cluster by any number of OSDs if it is enabled.

3.2.1. Add capacity with 3 OSDs using the Add Capacity option

To add capacity by 3 OSDs for dynamic and local storage using the Add Capacity option in the user interface, see Scaling up storage by adding capacity. The Add Capacity option is available for storage clusters with or without the flexible scaling feature enabled.

3.2.2. Add capacity using YAML

With flexible scaling enabled, you can add capacity by 1 or more OSDs at a time using the YAML instead of the default set of 3 OSDs. However, you need to make sure that you add disks in a way that the cluster remains balanced.

Flexible scaling is supported only for the internal-attached mode of storage cluster creation. Flexible scaling of storage clusters is available only for the new deployments of Red Hat OpenShift Container Storage 4.7 and not for the upgraded clusters.

To enable flexible scaling, create a cluster with 3 nodes, and fewer than 3 availability zones. The OpenShift Web Console detects the 3 nodes spread across fewer than 3 availability zones and enables flexible scaling.

Important

You can not enable or disable the flexible scaling feature after creating the storage cluster.

3.2.2.1. Verifying if flexible scaling is enabled

To verify if flexible scaling is enabled on your storage cluster, perform the following steps:

  1. Click OpenShift Container Storage Operator.
  2. Click the Storage Cluster tab.
  3. Click on the action menu (⋮) next to the storage cluster.
  4. Click Edit Storage Cluster. You are redirected to the YAML.

  5. In the YAML, search for the keys flexibleScaling in spec section and failureDomain in status section. If flexible scaling is true and failureDomain is set to host, flexible scaling feature is enabled. 

    spec:
flexibleScaling: true
[…]
status:
failureDomain: host
3.2.2.2. Adding capacity using the YAML in multiples of 1 OSD

To add OSDs to your storage cluster flexibly through the YAML, perform the following steps:

Prerequisites

  • Administrator access to the OpenShift Container Platform web console.
  • A storage cluster with flexible scaling enabled.
  • Additional disks available for adding capacity.

Procedure

  1. Click Operators → Installed Operators to view all the installed operators. Ensure that the Project selected is openshift-storage.
  2. Click the OpenShift Container Storage operator.
  3. Click the Storage Cluster tab.
  4. Click on the action menu (⋮) next to the storage cluster you want to scale up.
  5. Click Edit Storage Cluster. You are redirected to the YAML.
  6. In YAML, search for the key count . This count parameter scales up the capacity.

  7. Increase the count by the number of OSDs you want to add to your cluster.

    Important

    Ensure the count parameter in YAML is incremented depending on the number of available disks and also make sure that you add disks in a way that the cluster remains balanced.

  8. Click Save.

You might need to wait a couple of minutes for the storage cluster to reach the Ready state.

Verification steps

  • Navigate to Overview → Persistent Storage tab, then check the Raw Capacity breakdown card.

    Note that the capacity increases based on your selections.

    Note

    The raw capacity does not take replication into account and shows the full capacity.

  • Verify that the new OSDs and their corresponding new PVCs are created.

    • To view the state of the newly created OSDs:

      1. Click Workloads → Pods from the OpenShift Web Console.
      2. Select openshift-storage from the Project drop-down list.

    • To view the state of the PVCs:

      1. Click Storage → Persistent Volume Claims from the OpenShift Web Console.
      2. Select openshift-storage from the Project drop-down list.

  • (Optional) If cluster-wide encryption is enabled on the cluster, verify that the new OSD devices are encrypted.

    1. Identify the node(s) where the new OSD pod(s) are running. 

      $ oc get -o=custom-columns=NODE:.spec.nodeName pod/<OSD pod name>

      For example: 

      oc get -o=custom-columns=NODE:.spec.nodeName pod/rook-ceph-osd-0-544db49d7f-qrgqm

    2. For each of the nodes identified in previous step, do the following:

      1. Create a debug pod and open a chroot environment for the selected host(s). 

        $ oc debug node/<node name>
$ chroot /host

      2. Run “lsblk” and check for the “crypt” keyword beside the ocs-deviceset name(s) 

        $ lsblk
Important

OpenShift Container Storage does not support cluster reduction either by reducing OSDs or reducing nodes.

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