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Bug #65085

closed

rados: replica mlcod tends to lag by two cycles rather than one limiting replica reads

Added by Samuel Just almost 2 years ago. Updated 5 months ago.

Status:
Resolved
Priority:
Normal
Assignee:
Samuel Just
Category:
-
Target version:
Ceph - v20.0.0
% Done:

100%

Source:
Development
Backport:
Regression:
No
Severity:
3 - minor
Reviewed:
Affected Versions:
ceph-qa-suite:
Component(RADOS):
OSD
Pull request ID:
56677
Tags (freeform):
Merge Commit:
048ce81f45a4af62c7a2712abe4ec5ce7b09d278
Fixed In:
v19.3.0-5934-g048ce81f45
Released In:
v20.2.0~1668
Upkeep Timestamp:
2025-11-01T01:19:28+00:00

Description

The replica and the primary populate RepModify::last_complete and RepGather::pg_local_last_complete prior to doing PrimaryLogPG::log_operation. This causes the last_complete_ondisk value and consequently min_last_complete_ondisk to lag by an additional write cycle (mlcod on replicas will tend to lag last_update by two versions rather than one). The practical consequence of this is mainly the objects written in the last two log versions will be unavailable for replica read rather than the last one.

See https://tracker.ceph.com/issues/65013 for debugging process/discussion.

Related issues 2 (0 open — 2 closed)

Related to RADOS - Bug #65013: replica_read not available on most recently updated objects in each PGResolvedSamuel Just

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Related to crimson - Feature #68828: Support MSG_OSD_PG_PCTResolvedSamuel Just

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 #1

Updated by Samuel Just almost 2 years ago

  • Related to Bug #65013: replica_read not available on most recently updated objects in each PG added
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 #2

Updated by Samuel Just almost 2 years ago

  • Description updated (diff)
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 #3

Updated by Samuel Just over 1 year ago

  • Status changed from New to Fix Under Review
  • Pull request ID set to 66316
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 #4

Updated by Laura Flores over 1 year ago

@Samuel Just this has the wrong PR id.

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 #5

Updated by Samuel Just over 1 year ago

  • Pull request ID changed from 66316 to 56677
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 #6

Updated by Matan Breizman over 1 year ago

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 #7

Updated by Samuel Just over 1 year ago

  • Status changed from Fix Under Review to Resolved
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 #8

Updated by Konstantin Shalygin about 1 year ago

  • Assignee set to Samuel Just
  • Target version set to v20.0.0
  • % Done changed from 0 to 100
  • Source set to Development
  • Component(RADOS) OSD added
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 #9

Updated by Upkeep Bot 8 months ago

  • Merge Commit set to 048ce81f45a4af62c7a2712abe4ec5ce7b09d278
  • Fixed In set to v19.3.0-5934-g048ce81f45a
  • Upkeep Timestamp set to 2025-07-11T14:11:56+00:00
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 #10

Updated by Upkeep Bot 8 months ago

  • Fixed In changed from v19.3.0-5934-g048ce81f45a to v19.3.0-5934-g048ce81f45
  • Upkeep Timestamp changed from 2025-07-11T14:11:56+00:00 to 2025-07-14T23:10:03+00:00
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 #11

Updated by Upkeep Bot 5 months ago

  • Released In set to v20.2.0~1668
  • Upkeep Timestamp changed from 2025-07-14T23:10:03+00:00 to 2025-11-01T01:19:28+00:00
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