Bug 810877

Summary:	VMs started on more than one host
Product:	Red Hat Enterprise Linux 6	Reporter:	Lon Hohberger <lhh>
Component:	rgmanager	Assignee:	Ryan McCabe <rmccabe>
Status:	CLOSED NOTABUG	QA Contact:	Cluster QE <mspqa-list>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	6.3	CC:	cluster-maint, sbradley
Target Milestone:	rc	Keywords:	Documentation
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2012-04-09 14:19:21 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:

Comment 2 Lon Hohberger 2012-04-09 14:01:59 UTC

Description of problem:

* If the libvirt-guests initscript is enabled while rgmanager is managing the
-same- virtual machines, the initscript, being not cluster-aware, will start
VMs already under rgmanager control on other hosts in the cluster.

* If the guests are configured to autostart using 'virsh autostart', the
libvirt tools will automatically start the virtual machines already under
rgmanager control on other hosts in the cluster.

These situations can end up with data loss in the virtual machines.

When running the cluster software to manage virtual machines, it is very
important to adhere to the following:

1) The libvirt-guests init script must be disabled.

2) All guests configured for cluster control must be disabled from an
auto-start perspective (e.g. virsh autostart --disable myvm1).

3) It is a best practice to use a non-default path for storing virtual machine
configuration files.  For example, use /mnt/guests (the default is
/etc/libvirt/qemu).  NOTE: If this is correctly done, steps (1) and (2) may not
be necessary.

4) Cluster-managed virtual machines must be managed using the cluster software.
 Do not mix usage of virt-manager, virsh, or other tools with rgmanager / luci.


The combination of these provide the following benefits:

a) Deterministic virtual machine behavior

b) Prevention of accidental management by other, non-cluster tools.