Feature #17350

Updated by Nico C├ęsar 10 months ago

Once #17349 is done, railsapi will have "replicas_desired" with some values that accept several storage classes.

In this ticket
As example some are listed in the assumption column "Collection effective value" from the valid entries.

Assumption
there are 600 blocks equally distributed in the volumes

h2. Volumes scenario

h3. Scenario 1
<pre>
---
Clusters:
test1:
Collections:
DefaultReplication: 1
Volumes:
test1-nyw5e-000000000000000:
AccessViaHosts:
'http://keep0:25107': {}
test1-nyw5e-111111111111111:
AccessViaHosts:
'http://keep1:25108': {}
</pre>

h3. Scenario 2
<pre>
---
Clusters:
test1:
Collections:
DefaultReplication: 1
Volumes:
test1-nyw5e-000000000000000:
AccessViaHosts:
'http://keep0:25107': {}
test1-nyw5e-111111111111111:
AccessViaHosts:
'http://keep1:25108': {}
StorageClasses:
archival: true
</pre>

h3. Scenario 3
<pre>
---
Clusters:
test1:
Collections:
DefaultReplication: 1
Volumes:
test1-nyw5e-000000000000000:
AccessViaHosts:
'http://keep0:25107': {}
test1-nyw5e-111111111111111:
AccessViaHosts:
'http://keep1:25108': {}
StorageClasses:
archival: true
Read-Only
</pre>

h2. Expected result after tunnign keep balance

|_. Volumes scenario | Expected result after keep-balance run |
| 1 | 300 blocks in each volume |
| 2 | 600 blocks in test1-nyw5e-000000000000000 and 600 blocks in test1-nyw5e-111111111111111 |
| 3 | 600 blocks in test1-nyw5e-000000000000000 and 300 blocks in test1-nyw5e-111111111111111 |

To be talked in next grooming session (Feb 16th)

* What are the common usecase ?
* What other scenarios we care about?
* How we address the process of changing configuration and re-running keep-balance?

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