Bug 763924 (GLUSTER-2192)

Summary:	add-brick and remove-brick changes order of subvolumes
Product:	[Community] GlusterFS	Reporter:	Harshavardhana <fharshav>
Component:	glusterd	Assignee:	tcp
Status:	CLOSED NOTABUG	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	3.1.1	CC:	amarts, cww, gluster-bugs, krishna, vijay
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	RTNR	Mount Type:	---
Documentation:	DNR	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:

Description Harshavardhana 2010-12-05 07:11:00 UTC

For example if you have 48 bricks :- 

Remove 5 bricks and add 5 bricks, adding bricks are not sequential and never maintain proper topology. 

This topology or order of sub-volumes is important in case of distribute. 

Such a change in topology results in a live i/o to exit. But its a problem as the order of sub-volumes has changed, distribute tries to rehash everything and writes new layout. 

This case was tested @ customer site during LUN migration. 

Current solution is to use replace-brick over a stopped volume to do in-place brick replacement.

Comment 1 tcp 2011-01-20 10:58:05 UTC

I am not clear about what the actual problem is.

Are we adding a new brick, or are we adding the old ones back (with no change in data but with a change in the brick parameters - like change in hostname, change in path etc) ?

Can you please elaborate on the LUN migration setup ? And, elucidate what the actual problem is ? Do you mean that the problem in such a scenario is that the rehashing will cause in creation of lot of link files?

Comment 2 tcp 2011-01-25 06:16:07 UTC

Can you please respond to the update?

Comment 3 Harshavardhana 2011-01-26 22:16:13 UTC

(In reply to comment #2)
> Can you please respond to the update?


Resolving this since, replace-brick fixes the issue.