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Bug #47613

open

pg autoscaler: don't always treat target ratios as a weight

Added by Dan van der Ster over 3 years ago. Updated over 3 years ago.

Status:
New
Priority:
High
Assignee:
-
Category:
-
Target version:
-
% Done:

0%

Source:
Community (dev)
Tags:
Backport:
Regression:
Yes
Severity:
2 - major
Reviewed:
Affected Versions:
ceph-qa-suite:
Pull request ID:
Crash signature (v1):
Crash signature (v2):

Description

https://tracker.ceph.com/issues/43947 has an undesireable bootstrapping effect that if an admin sets the target ratio of just one pool to a small value, e.g. 0.1, on a new cluster, the ceph will immediately scale that up to 1.0 and therefore consume all of the PGs for a cluster. (Once they add target ratios to other pools, then those PGs will eventually be merged, but this is all a complex waste of IO, imho).

IMHO it would be more intuitive if we treat target ratios as weights only if their sum is >1. If their sum is <1, we should use them as-is.

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