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Bug #27000

mgr balancer does not save optimized plan but latest

Added by Stefan Priebe 4 months ago. Updated 3 months ago.

Status:
Resolved
Priority:
Normal
Assignee:
-
Category:
balancer module
Target version:
-
Start date:
08/22/2018
Due date:
% Done:

100%

Source:
Tags:
Backport:
luminous,mimic
Regression:
No
Severity:
3 - minor

Description

The current balancer module fails to deepcopy the optimized plan so that best_ws and best_ow are modified later.

Example log which might explain everything:
It fixes the following (mgr debug output):
2018-08-20 22:33:46.078525 7f2fbc3b6700 0 mgr[balancer] Step result
score 0.001152 -> 0.001180, misplacing 0.000912
2018-08-20 22:33:46.078574 7f2fbc3b6700 0 mgr[balancer] Score got
worse, taking another step
2018-08-20 22:33:46.078770 7f2fbc3b6700 0 mgr[balancer] Balancing root
default (pools ['cephstor2']) by bytes
2018-08-20 22:33:46.156326 7f2fbc3b6700 0 mgr[balancer] Step result
score 0.001152 -> 0.001180, misplacing 0.000912
2018-08-20 22:33:46.156374 7f2fbc3b6700 0 mgr[balancer] Score got
worse, taking another step
2018-08-20 22:33:46.156581 7f2fbc3b6700 0 mgr[balancer] Balancing root
default (pools ['cephstor2']) by bytes
2018-08-20 22:33:46.233818 7f2fbc3b6700 0 mgr[balancer] Step result
score 0.001152 -> 0.001180, misplacing 0.000912
2018-08-20 22:33:46.233868 7f2fbc3b6700 0 mgr[balancer] Score got
worse, taking another step
2018-08-20 22:33:46.234043 7f2fbc3b6700 0 mgr[balancer] Balancing root
default (pools ['cephstor2']) by bytes
2018-08-20 22:33:46.313212 7f2fbc3b6700 0 mgr[balancer] Step result
score 0.001152 -> 0.001180, misplacing 0.000912
2018-08-20 22:33:46.313714 7f2fbc3b6700 0 mgr[balancer] Score got
worse, trying smaller step 0.000244
2018-08-20 22:33:46.313887 7f2fbc3b6700 0 mgr[balancer] Balancing root
default (pools ['cephstor2']) by bytes
2018-08-20 22:33:46.391586 7f2fbc3b6700 0 mgr[balancer] Step result
score 0.001152 -> 0.001152, misplacing 0.001141
2018-08-20 22:33:46.393374 7f2fbc3b6700 0 mgr[balancer] Balancing root
default (pools ['cephstor2']) by bytes
2018-08-20 22:33:46.473956 7f2fbc3b6700 0 mgr[balancer] Step result
score 0.001152 -> 0.001180, misplacing 0.000912
2018-08-20 22:33:46.474001 7f2fbc3b6700 0 mgr[balancer] Score got
worse, taking another step
2018-08-20 22:33:46.474046 7f2fbc3b6700 0 mgr[balancer] Success, score
0.001155 -> 0.001152

BUT:
  1. ceph balancer eval myplan
    plan myplan final score 0.001180 (lower is better)

So the final plan does NOT contain the expected optimization. The
deepcopy fixes it.

after the patch applied (see PR on github):
  1. ceph balancer eval myplan
    plan myplan final score 0.001152 (lower is better)

Related issues

Copied to mgr - Backport #32080: luminous: mgr balancer does not save optimized plan but latest Resolved
Copied to mgr - Backport #32082: mimic: mgr balancer does not save optimized plan but latest Resolved

History

#2 Updated by Nathan Cutler 4 months ago

  • Status changed from New to Need Review

#3 Updated by Kefu Chai 4 months ago

  • Status changed from Need Review to Pending Backport

#5 Updated by Nathan Cutler 4 months ago

  • Copied to Backport #32080: luminous: mgr balancer does not save optimized plan but latest added

#6 Updated by Nathan Cutler 4 months ago

  • Copied to Backport #32082: mimic: mgr balancer does not save optimized plan but latest added

#7 Updated by Nathan Cutler 3 months ago

  • Status changed from Pending Backport to Resolved

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