Bug 1375389

Summary:	[Doc] Wrongly mentioned primary OSD number in storage strategies guide
Product:	Red Hat Ceph Storage	Reporter:	Prashant Dhange <pdhange>
Component:	Documentation	Assignee:	Bara Ancincova <bancinco>
Status:	CLOSED CURRENTRELEASE	QA Contact:	ceph-qe-bugs <ceph-qe-bugs>
Severity:	medium	Docs Contact:
Priority:	unspecified
Version:	2.0	CC:	kdreyer
Target Milestone:	rc
Target Release:	2.1
Hardware:	x86_64
OS:	Linux
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Fixed In Version:		Doc Type:	If docs needed, set a value
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Last Closed:	2016-09-30 17:21:18 UTC	Type:	Bug
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Description Prashant Dhange 2016-09-13 01:04:02 UTC

Description of problem:
Document Red_Hat_Ceph_Storage-2-Storage_Strategies_Guide-en-US, Chapter 3 - Section 3.1. ABOUT PLACEMENT GROUPS
https://access.redhat.com/documentation/en/red-hat-ceph-storage/2/paged/storage-strategies-guide/chapter-3-placement-groups-pgs

The below section has minor mistake with primary OSD 1 is being documented instead of primary OSD 5.

For example, if CRUSH assigns an object to a placement group, and the placement group is assigned to OSD 5 as the primary OSD, if CRUSH calculates that OSD 1 and OSD 8 are secondary OSDs for the placement group, the primary OSD 1 will copy the data to OSDs 1 and 8. By copying data on behalf of clients, Ceph simplifies the client interface and reduces the client workload.

Version-Release number of selected component (if applicable):
Ceph 2.0

How reproducible:

Steps to Reproduce:
1.
2.
3.

Actual results:
For example, if CRUSH assigns an object to a placement group, and the placement group is assigned to OSD 5 as the primary OSD, if CRUSH calculates that OSD 1 and OSD 8 are secondary OSDs for the placement group, the primary OSD 1 will copy the data to OSDs 1 and 8. By copying data on behalf of clients, Ceph simplifies the client interface and reduces the client workload.

Expected results:
For example, if CRUSH assigns an object to a placement group, and the placement group is assigned to OSD 5 as the primary OSD, if CRUSH calculates that OSD 1 and OSD 8 are secondary OSDs for the placement group, the primary OSD 5 will copy the data to OSDs 1 and 8. By copying data on behalf of clients, Ceph simplifies the client interface and reduces the client workload.

Additional info:

Comment 3 Prashant Dhange 2016-09-13 01:10:41 UTC

There is another minor mistake in section 3.1, "will" repeated twice:

Should the primary OSD fail and get marked out of the cluster, CRUSH will assign the placement group to another OSD, which will will receive copies of objects in the placement group. Another OSD in the Up Set will assume the role of the primary OSD.

Expected:
Should the primary OSD fail and get marked out of the cluster, CRUSH will assign the placement group to another OSD, which will receive copies of objects in the placement group. Another OSD in the Up Set will assume the role of the primary OSD.