Supervised optimization

Break down the balancer operations in a phased manner.

About this task

The balancer operation is broken into a few distinct phases.

Procedure

Build a plan.
Evaluate the quality of the data distribution, either for the current PG distribution, or the PG distribution that might result after running a plan.
Run the plan.
1. Evaluate and score the current distribution.
```
ceph balancer eval
```
2. Evaluate the distribution for a single pool.
```
ceph balancer eval POOL_NAME
```
  For example,
```
[ceph: root@host01 /]# ceph balancer eval rbd
```
3. See a greater detail for the evaluation.
```
ceph balancer eval-verbose ...
```
4. Generate a plan using the currently configured mode.
```
ceph balancer optimize PLAN_NAME
```
  Replace PLAN_NAME with a custom plan name.
  For example,
```
[ceph: root@host01 /]# ceph balancer optimize rbd_123
```
5. See the contents of a plan.
```
ceph balancer show PLAN_NAME
```
  For example,
```
[ceph: root@host01 /]# ceph balancer show rbd_123
```
6. Discard old plans.
```
ceph balancer rm PLAN_NAME
```
  For example,
```
[ceph: root@host01 /]# ceph balancer rm rbd_123
```
7. See currently recorded plans use the status command.
```
ceph balancer status
```
8. Calculate the quality of the distribution that would result after executing a plan.
```
ceph balancer eval PLAN_NAME
```
  For example,
```
[ceph: root@host01 /]# ceph balancer eval rbd_123
```
9. Run the plan.
```
ceph balancer execute PLAN_NAME
```
  For example,
```
[ceph: root@host01 /]# ceph balancer execute rbd_123
```
  Note: Only run the plan if it is expected to improve the distribution. After execution, the plan is discarded.