Chapter 20. Setting Ceph OSD full thresholds

You can set Ceph OSD full thresholds temporarily by using the ODF CLI tool. This is necessary in cases when the cluster gets into a full state and the thresholds need to be immediately increased.

The following examples demonstrate how to use each subcommand:

full

This subcommand allows updating the Ceph OSD full ratio in case Ceph prevents the IO operation on OSDs that reached the specified capacity. The default is 0.85.

For example, set Ceph OSD full ratio to 0.9 and then add capacity:

$ odf set full 0.9

For instructions to add capacity for you specific use case, see the Scaling storage guide.

If OSDs continue to be in stuck, pending, or do not come up at all:

backfillfull

This subcommand allows updating the Ceph OSDd backfillfull ratio in case Ceph denies backfilling to the OSD that reached the capacity specified. The default value is 0.80.

For example, set backfillfull to 0.85:

$ odf set backfillfull 0.85

nearfull

This subcommand allows updating the Ceph OSD nearfull ratio in case Ceph returns the nearfull OSDs message when the cluster reaches the capacity specified. The default value is 0.75.

For example, set nearfull to 0.8:

$ odf set nearfull 0.8

You can set Ceph OSD full thresholds by updating the StorageCluster CR. Use this procedure if you want to override the default settings.

full

Use this following command to update the Ceph OSD full ratio in case Ceph prevents the IO operation on OSDs that reached the specified capacity. The default is 0.85.

For example, to set Ceph OSD full ratio to 0.9:

$ oc patch storagecluster ocs-storagecluster -n openshift-storage --type json --patch '[{ "op": "replace", "path": "/spec/managedResources/cephCluster/fullRatio", "value": 0.90 }]'

backfillfull

Use the following command to set the Ceph OSDd backfillfull ratio in case Ceph denies backfilling to the OSD that reached the capacity specified. The default value is 0.80.

For example, set backfill full to 0.85:

$ oc patch storagecluster ocs-storagecluster -n openshift-storage --type json --patch '[{ "op": "replace", "path": "/spec/managedResources/cephCluster/backfillFullRatio", "value": 0.85 }]'

nearfull

Use the following command to set the Ceph OSD nearfull ratio in case Ceph returns the nearfull OSDs message when the cluster reaches the capacity specified. The default value is 0.75.

For example, set nearfull to 0.8:

$ oc patch storagecluster ocs-storagecluster -n openshift-storage --type json --patch '[{ "op": "replace", "path": "/spec/managedResources/cephCluster/nearFullRatio", "value": 0.8 }]'