Bug 1249042

Summary: [GSS] Add a use-case for the CRUSH OSD tunable "osd crush update on start" in RHCS1.3 Storage Strategies documentation
Product: [Red Hat Storage] Red Hat Ceph Storage Reporter: Vimal Kumar <vikumar>
Component: DocumentationAssignee: ceph-docs <ceph-docs>
Status: CLOSED CURRENTRELEASE QA Contact: ceph-qe-bugs <ceph-qe-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 1.3.0CC: asriram, kdreyer, ngoswami, tmuthami
Target Milestone: rc   
Target Release: 1.3.2   
Hardware: All   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2015-12-18 10:07:19 UTC Type: Bug
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Vimal Kumar 2015-07-31 12:21:54 UTC 
a) Description of problem:

Add a use-case for the CRUSH OSD tunable "osd crush update on start" under the section "4.1.1. ceph-crush-location hook" in RHCS1.3 Storage Strategies documentation.

If a user sets a custom hostname for an OSD node in CRUSH map, and the OSD process or the node is restarted, the CRUSH maps get reverted back to the initial state. This makes the custom settings vanish.

In order to overcome this, set "osd crush update on start = false" in /etc/ceph/ceph.conf and push the configuration to the OSD/MON nodes with :

# ceph-deploy --overwrite-conf config push <node1> <node2> ... <nodeN>


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

RHCS1.2.3 Storage Strategies documentation.

NOTE: Editing a crush map and setting custom hostnames for rulesets and buckets are something customers do usually. The Crush map will revert back to the default as per the OSD hierarchy, if this tunable is not set. We need to get this added as a use-case.
Comment 2 John Wilkins 2015-09-14 21:55:52 UTC 
This seems like it might be useful to mention in a few more places. For example, the installation guide's section on creating a CRUSH hierarchy, and maybe the details for creating a CRUSH hierarchy. Alternatively, perhaps we should instruct the user to add `crush_location` when adding an OSD to a CRUSH hierarchy so this setting doesn't need to be set.
Comment 3 John Wilkins 2015-09-14 21:56:32 UTC 
https://gitlab.cee.redhat.com/jowilkin/red-hat-ceph-storage-strategies-guide/commit/5e9ac01e9c034fc814016f5481dcb1fb602028c0
Comment 4 Nilamdyuti 2015-10-09 13:08:32 UTC 
Here's the doc link:

https://gitlab.cee.redhat.com/jowilkin/red-hat-ceph-storage-strategies-guide/blob/v1.3/crush-admin.adoc
Comment 5 Tamil 2015-10-10 00:53:21 UTC 
verified on 1.3.0 and it looks good