Hi Koushik: In general I like the idea. A couple of comments:
The upgrade section has a manual step for enabling HA manually per instance. Why a manual step? Why is CloudStack not checking the desired state (e.g. if HA is enabled in the instance service group) with the actual state (what is reflected on the hypervisor) and changing it when appropriate. We are already going to need to reconcile the state (things like host the instance is running on will change for instance) with reality already - so it seems like making this an automatic step wouldn't be much extra effort and would scale far easier. Are there plans on deprecating the custom HA solution, or will it be supported forever? If the plan is to deprecate, lets go ahead and start planning that/announcing/etc and not let it fall into disrepair. --David On Fri, Nov 22, 2013 at 7:27 AM, Koushik Das <koushik....@citrix.com> wrote: > Initial draft of the FS > https://cwiki.apache.org/confluence/display/CLOUDSTACK/User+VM+HA+using+native+XS+HA+capabilities > > -Koushik > > On 21-Nov-2013, at 9:59 AM, Koushik Das <koushik....@citrix.com> wrote: > >> Cloudstack relies on custom HA logic for user VMs running on Xenserver. The >> reason for doing it like this may be due the fact that native HA >> capabilities in XS was not mature enough during the initial days. Also in >> the custom HA logic, Cloudstack has to correctly determine the state of a VM >> from the hypervisor before it can take any action. In case there are any >> issues in determining the state, HA mechanism can get impacted. Since the >> hypervisor best knows the state of the VM it is a better approach to rely on >> native HA capabilities. >> >> The idea is to rely on native HA capabilities for user VMs from XS 6.2 >> onwards. HA for system VMs would still be based on application logic. For >> sake of backward compatibility the earlier option will be there as well and >> there will be a choice to use any one option. >> >> The additional requirement for this is to pre-configure native HA on a >> Xenserver cluster before deploying any user VMs as documented here [1]. >> >> I have created a ticket in Jira [2]. I will post the FS for this shortly. >> >> Thanks, >> Koushik >> >> [1] >> http://support.citrix.com/servlet/KbServlet/download/34969-102-704897/reference.pdf >> (refer section 3.8) >> [2] https://issues.apache.org/jira/browse/CLOUDSTACK-5203 >> >> >
