Add, remove, or reconfigure Ceph OSDs#

Pelagia Lifecycle Management (LCM) Controller simplifies Ceph cluster management by automating LCM operations. This section describes how to add, remove, or reconfigure Ceph OSDs.

Add a Ceph OSD #

Manually prepare the required devices on the existing node.
Optional. If you want to add a Ceph OSD on top of a raw device that already exists on a node or is hot-plugged, add the required device using the following guidelines:
- You can add a raw device to a node during node deployment.
- If a node supports adding devices without a node reboot, you can hot plug a raw device to a node.
- If a node does not support adding devices without a node reboot, you can hot plug a raw device during node shutdown.
Open the CephDeployment custom resource (CR) for editing:
```
kubectl -n pelagia edit cephdpl
```
In one of the following sections, specify parameters for Ceph OSD:
- nodes.<nodeName>.devices
- nodes.<nodeName>.deviceFilter
- nodes.<nodeName>.devicePathFilter
For description of parameters, see CephDeployment: Nodes parameters.

The example configuration of the nodes section with the new node:
```
nodes:
- name: storage-worker-52
  roles:
  - mon
  - mgr
  devices:
  - config: # existing item
      deviceClass: hdd
    fullPath: /dev/disk/by-id/scsi-SATA_HGST_HUS724040AL_PN1334PEHN18ZS
  - config: # new item
      deviceClass: hdd
    fullPath: /dev/disk/by-id/scsi-0ATA_HGST_HUS724040AL_PN1334PEHN1VBC
```
Warning

We highly recommend using the non-wwn by-id symlinks to specify storage devices in the devices list. For details, see Architecture: Addressing Ceph devices.

Verify that the Ceph OSD on the specified node is successfully deployed. The CephDeploymentHealth CR status.healthReport.cephDaemons.cephDaemons section should not contain any issues.

kubectl -n pelagia get cephdeploymenthealth -o yaml

For example:

status:
  healthReport:
    cephDaemons:
      cephDaemons:
        osd:
          info:
          - 3 osds, 3 up, 3 in
          status: ok

Verify the desired Ceph OSD pod is Running:

kubectl -n rook-ceph get pod -l app=rook-ceph-osd -o wide | grep <nodeName>

Remove a Ceph OSD #

Note

Ceph OSD removal presupposes usage of a CephOsdRemoveTask CR. For workflow overview, see High-level workflow of Ceph OSD or node removal.

Warning

When using the non-recommended Ceph pools replicated.size of less than 3, Ceph OSD removal cannot be performed. The minimal replica size equals a rounded up half of the specified replicated.size.

For example, if replicated.size is 2, the minimal replica size is 1, and if replicated.size is 3, then the minimal replica size is 2. The replica size of 1 allows Ceph having PGs with only one Ceph OSD in the acting state, which may cause a PG_TOO_DEGRADED health warning that blocks Ceph OSD removal. We recommend setting replicated.size to 3 for each Ceph pool.

Open the CephDeployment CR on for editing:
```
kubectl -n pelagia edit cephdpl
```

Remove the required Ceph OSD specification from the spec.nodes.<nodeName>.devices list:

The example configuration of the nodes section with removing device:

nodes:
- name: storage-worker-52
  roles:
  - mon
  - mgr
  devices:
  - config:
      deviceClass: hdd
    fullPath: /dev/disk/by-id/scsi-SATA_HGST_HUS724040AL_PN1334PEHN18ZS
  - config: # remove the entire item entry from devices list
      deviceClass: hdd
    fullPath: /dev/disk/by-id/scsi-0ATA_HGST_HUS724040AL_PN1334PEHN1VBC

Create a YAML template for the CephOsdRemoveTask CR. Select from the following options:
- Remove Ceph OSD by device name, by-path symlink, or by-id symlink:
```
apiVersion: lcm.mirantis.com/v1alpha1
kind: CephOsdRemoveTask
metadata:
  name: remove-osd-<nodeName>-task
  namespace: pelagia
spec:
  nodes:
    <nodeName>:
      cleanupByDevice:
      - device: sdb
```
  Warning
  
  We do not recommend setting device name or device by-path symlink in the cleanupByDevice field as these identifiers are not persistent and can change at node boot. Remove Ceph OSDs with by-id symlinks or use cleanupByOsdId instead. For details, see Architecture: Addressing Ceph devices.
  
  Note
  
  If a device was physically removed from a node, cleanupByDevice is not supported. Therefore, use cleanupByOsdId instead.
- Remove Ceph OSD by OSD ID:
```
apiVersion: lcm.mirantis.com/v1alpha1
kind: CephOsdRemoveTask
metadata:
  name: remove-osd-<nodeName>-task
  namespace: pelagia
spec:
  nodes:
    <nodeName>:
      cleanupByOsdId:
      - id: 2
```

Apply the template:

kubectl apply -f remove-osd-<nodeName>-task.yaml

Verify that the corresponding request has been created:

kubectl -n pelagia get cephosdremovetask remove-osd-<nodeName>-task

Verify that the removeInfo section appeared in the CephOsdRemoveTask CR status:

kubectl -n pelagia get cephosdremovetask remove-osd-<nodeName>-task -o yaml

Example of system response:

status:
  removeInfo:
    cleanupMap:
      storage-worker-52:
        osdMapping:
          "2":
            deviceMapping:
              sdb:
                path: "/dev/disk/by-path/pci-0000:00:1t.9"
                partition: "/dev/ceph-b-vg_sdb/osd-block-b-lv_sdb"
                type: "block"
                class: "hdd"
                zapDisk: true

Verify that the cleanupMap section matches the required removal and wait for the ApproveWaiting phase to appear in status:
```
kubectl -n pelagia get cephosdremovetask remove-osd-<nodeName>-task -o yaml
```
Example of system response:
```
status:
  phase: ApproveWaiting
```

Edit the CephOsdRemoveTask CR and set the approve flag to true:

kubectl -n pelagia edit cephosdremovetask remove-osd-<nodeName>-task

For example:

spec:
  approve: true

Review the following status fields of the Ceph LCM CR processing:
- status.phase - current state of request processing;
- status.messages - description of the current phase;
- status.conditions - full history of request processing before the current phase;
- status.removeInfo.issues and status.removeInfo.warnings - error and warning messages occurred during request processing, if any.

Verify that the CephOsdRemoveTask has been completed. For example:

status:
  phase: Completed # or CompletedWithWarnings if there are non-critical issues

Remove the device cleanup jobs:

kubectl delete jobs -n pelagia -l app=pelagia-lcm-cleanup-disks

Reconfigure a Ceph OSD#

There is no hot reconfiguration procedure for existing Ceph OSDs. To reconfigure an existing Ceph OSD, follow the steps below:

Remove a Ceph OSD from the Ceph cluster as described in Remove a Ceph OSD.
Add the same Ceph OSD but with a modified configuration as described in Add a Ceph OSD.