Bug 1372846 - [Documentation] use the supported values for K/M options for Erasure Coding
Summary: [Documentation] use the supported values for K/M options for Erasure Coding
Keywords:
Status: CLOSED CURRENTRELEASE
Alias: None
Product: Red Hat Ceph Storage
Classification: Red Hat Storage
Component: Documentation
Version: 2.0
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: 2.3
Assignee: Aron Gunn
QA Contact: Vidushi Mishra
URL:
Whiteboard:
Depends On:
Blocks: 1437903
TreeView+ depends on / blocked
 
Reported: 2016-09-02 22:06 UTC by Neil Levine
Modified: 2020-07-16 08:53 UTC (History)
16 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2017-06-20 18:23:10 UTC
Embargoed:


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Links
System ID Private Priority Status Summary Last Updated
Ceph Project Bug Tracker 18188 0 None None None 2016-12-08 06:53:50 UTC
Red Hat Bugzilla 1456580 0 unspecified CLOSED [Doc] Example in Erasure Code Profiles report unsupported configuration 2021-02-22 00:41:40 UTC

Internal Links: 1456580

Description Neil Levine 2016-09-02 22:06:03 UTC
Currently, we don't specify which k/m values we support. We need to explicitly test and document the following values which are the same used by RHGS.

1. 8+3
2. 8+4
3. 4+2

This will require upstream tests to be added too.

Support values should be documented at: https://access.redhat.com/articles/1548993

Comment 3 Neil Levine 2016-09-02 22:07:15 UTC
These values also need to be exposed on RHScon.

Comment 4 Loic Dachary 2016-10-20 18:41:23 UTC
From the point of view of data integrity we explicitly test the following combinations for

SHEC plugin: https://github.com/ceph/ceph-erasure-code-corpus/blob/master/v0.92-988/non-regression.sh#L66
LRC plugin: https://github.com/ceph/ceph-erasure-code-corpus/blob/master/v0.92-988/non-regression.sh#L94
ISA plugin: https://github.com/ceph/ceph-erasure-code-corpus/blob/master/v0.92-988/non-regression.sh#L113
jerasure plugin:
  with cauchy and cauchy_good techniques :
         https://github.com/ceph/ceph-erasure-code-corpus/blob/master/v0.92-988/non-regression.sh#L220
  with reed_sol_van technique:
         https://github.com/ceph/ceph-erasure-code-corpus/blob/master/v0.92-988/non-regression.sh#L243

From the point of view of how rados handles erasure coded pools we have:

LRC plugin with k=4,m=2,l=3
   https://github.com/ceph/ceph-qa-suite/blob/master/suites/rados/thrash-erasure-code-big/workloads/ec-rados-plugin%3Dlrc-k%3D4-m%3D2-l%3D3.yaml
ISA plugin with k=2,m=1
   https://github.com/ceph/ceph-qa-suite/blob/master/suites/rados/thrash-erasure-code-isa/workloads/ec-rados-plugin%3Disa-k%3D2-m%3D1.yaml
SHEC plugin with k=4,m=3,c=2
   https://github.com/ceph/ceph-qa-suite/blob/master/suites/rados/thrash-erasure-code-shec/workloads/ec-rados-plugin%3Dshec-k%3D4-m%3D3-c%3D2.yaml
jerasure plugin with k=2, m=1 and k=3, m=1

From the point of view of upgrades we are using the jerasure plugin with k=2, m=1 and scenarios verifying an erasure coded pool behaves during upgrades from:

  hammer to kraken : https://github.com/ceph/ceph-qa-suite/tree/master/suites/upgrade/hammer-x
  jewel to kraken : https://github.com/ceph/ceph-qa-suite/tree/master/suites/upgrade/jewel-x

Comment 6 Neil Levine 2016-10-21 21:27:07 UTC
Perfect! 

Ken: feels like we can turn this into a doc task. I am going to update the supported config page but we should also include the support K/M values explicitly in the erasure code section of our docs.

Comment 7 Neil Levine 2016-12-08 00:34:36 UTC
Can we add in 2+2 as well?

Comment 8 Loic Dachary 2016-12-08 06:53:51 UTC
@Neil added 2+2 tests upstream, scheduled for backport to jewel.

Comment 10 Josh Durgin 2017-04-01 01:18:29 UTC
https://access.redhat.com/documentation/en-us/red_hat_ceph_storage/2/html/storage_strategies_guide/erasure_code_pools#erasure_code_profiles

Does not mention anything about supported values.

Re-adding the accidentally cleared needinfo from Neil from comment #6

Comment 14 John Poelstra 2017-06-20 18:23:10 UTC
Closing this bug as the documentation has been published with the release


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