Bug 925981

Summary:	default migration bandwidth capping is not honored anymore
Product:	Red Hat Enterprise Virtualization Manager	Reporter:	Nandini Chandra <nachandr>
Component:	vdsm	Assignee:	Saveliev Peter <peet>
Status:	CLOSED ERRATA	QA Contact:	Pavel Stehlik <pstehlik>
Severity:	medium	Docs Contact:
Priority:	urgent
Version:	3.1.3	CC:	abaron, acathrow, bazulay, carlos.molina.ext, dyasny, hateya, iheim, italkohe, jentrena, lpeer, lyarwood, michal.skrivanek, pep, sgrinber, thildred, ykaul, zdover
Target Milestone:	---	Keywords:	ZStream
Target Release:	3.2.0
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	virt
Fixed In Version:	vdsm-4.10.2-16.0.el6ev	Doc Type:	Bug Fix
Doc Text:	Previously, libvirt changed the default behaviour from the limited migration bandwidth to unlimited one. This meant that without any migration bandwidth limitation, the network could be saturated during mass migrations. The default limit was set to "on". This solution is compatible with all versions, and preserves the original behaviour. This fix ensures that customers with large networks will notice no change in migration behavior.	Story Points:	---
Clone Of:
Clones:	950603 (view as bug list)		Environment:
Last Closed:	2013-06-10 20:46:30 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	948821
Bug Blocks:	950603

Description Nandini Chandra 2013-03-23 03:00:41 UTC

Description of problem:
The /usr/share/doc/<vdsm-version>/vdsm.conf.sample file has the following information.
# Maximum bandwidth for migration, in mbps, 0 means libvirt's default
# (30mbps?).
# migration_max_bandwidth = 0

In RHEL 6.4 with libvirt-0.10.2-18,the maximum available bandwidth is used by default for migration of KVM guests.So,this needs to be changed to reflect the change made in libvirt.

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Comment 1 Nandini Chandra 2013-03-23 03:02:58 UTC

http://libvirt.org/git/?p=libvirt.git;a=commitdiff;h=6cfdeaac552e1ef744f269ed4cef3d74e663d677

With this commit,the default maximum migration bandwidth of 32 Mb/s in the older versions of libvirt has been removed and in 
RHEL 6.4/libvirt-0.10.2-18.el6.x86_64.rpm,the maximum available bandwidth is used by default for migration of KVM guests.

-Nandini

Comment 2 Michal Skrivanek 2013-04-04 16:14:56 UTC

*** Bug 948353 has been marked as a duplicate of this bug. ***

Comment 3 Michal Skrivanek 2013-04-04 16:25:55 UTC

This can cause overload of network interfaces as the whole bandwidth is used in case of mass migration (either manual or induced by moving a host to maintenance mode) 

The fix would be to use the former 30Mbps value as the default in vdsm config.
something like:
-        ('migration_max_bandwidth', '0',
-            'Maximum bandwidth for migration, in mbps, 0 means libvirt\'s '
-            'default (30mbps?).'),
+        ('migration_max_bandwidth', '32',
+            'Maximum bandwidth for migration, in Mbps, 0 means unlimited, former libvirt\'s '
+            'default is 32Mbps.'),

plus we need to fix upgrade as well, I guess

Comment 10 Saveliev Peter 2013-04-11 07:36:50 UTC

merged as ovirt:9974c596737c5f59ad6c2add02111efc12cb1d1c

preparing backports

Comment 21 errata-xmlrpc 2013-06-10 20:46:30 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHSA-2013-0886.html