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Congratulations on upgrading your cluster to the Luminous release of Ceph. You have diligently followed all the steps outlined in the upgrade notes to the point where you are ready to mark the upgrade complete by executing the following:
$ ceph osd require-osd-release luminous
Once your cluster has been flagged as fully upgraded to the Luminous release, a new feature will be enabled: application pool tags.
Your first encounter with the new feature might possibly be in the form of a new health warning indicating that one or more of your in-use pools is missing an application tag:
$ ceph health HEALTH_WARN application not enabled on 3 pool(s) $ ceph health detail HEALTH_WARN application not enabled on 3 pool(s) POOL_APP_NOT_ENABLED application not enabled on 3 pool(s) application not enabled on pool 'block-devices' application not enabled on pool 'custom-application' application not enabled on pool 'object-gateway' use 'ceph osd pool application enable <pool-name> <app-name>', where <app-name> is 'cephfs', 'rbd', 'rgw', or freeform for custom applications.
As indicated by the detailed health message, these warnings can be disabled by running “ceph osd pool application enable <pool-name> <app-name>” for each pool listed. The <app-name> parameter is free-form, although we recommend that you use “rbd” for RBD-related pools and “rgw” for RGW-related pools. There should not be a need to ever manually tag a CephFS pool.
For example, the above health warnings can be cleared with
$ ceph osd pool application enable block-devices rbd $ ceph osd pool application enable custom-application mything $ ceph osd pool application enable object-gateway rgw
The final Luminous upgrade step via “ceph osd require-osd-release luminous” makes an attempt to automatically tag any existing pools with the appropriate application using the following heuristics:
Once the upgrade is complete, adding new pools to CephFS will automatically tag those pools as “cephfs”-owned and RGW will automatically tag any pools it creates as “rgw”-owned.
If you create a fresh Ceph cluster with Luminous, you’ll notice another change: there no default pools. Previously versions pre-created an “rbd” pool for you but Luminous does not presume to know what you will use the cluster for (or how many PGs are appropriate for your use-case).
If you will be using RBD, you’ll need to create the pool yourself. You may want to refer to the discussion of placement groups to decide what value for <pg_num> to use.
$ ceph osd pool create <pool-name> <pg_num>
Once the pool is created, there is a new rbd command to simplify the tagging of new RBD pools:
$ rbd pool init <pool-name>
Disregarding the potentially scary health warning, the absence or presence of application pool tags will not affect the behavior of your Luminous cluster. Yet. Pool tags were introduced into the system as a simple foundation for future features. Some of these future changes include: