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From Alex Huang <Alex.Hu...@citrix.com>
Subject RE: [PROPOSAL] User VM HA using native XS HA capabilities
Date Wed, 27 Nov 2013 21:59:21 GMT
Koushik,

How do you propose for XS HA to work with CloudStack's host affinity use cases?  I don't see
anything in the spec regarding this.  I generally don't think VM HA can be done with hypervisor
HA because of this.  

--Alex  

> -----Original Message-----
> From: Koushik Das [mailto:koushik.das@citrix.com]
> Sent: Tuesday, November 26, 2013 10:51 PM
> To: <dev@cloudstack.apache.org>
> Subject: Re: [PROPOSAL] User VM HA using native XS HA capabilities
> 
> I haven't tried in XS 6.1 but in 6.2 if a VM is marked as HA enabled (based on
> ha-restart-priority) in a HA enabled cluster then if the VM is not stopped
> using xapi then it is automatically re-started.
> 
> I tried the following on XS 6.2 and it worked as expected:
> - Logged on to a guest VM marked as HA enabled
> - Ran "shutdown -h now"
> - After sometime the VM got restarted
> 
> -Koushik
> 
> 
> On 27-Nov-2013, at 2:11 AM, Chiradeep Vittal <Chiradeep.Vittal@citrix.com>
> wrote:
> 
> > According to
> > http://support.citrix.com/proddocs/topic/xencenter-61/xs-xc-pools-ha-
> about.
> > html
> >
> >
> > XS HA is about dealing with host failures.
> > However CS HA also deals with individual VM failures ("fast restart").
> > I hope you are not removing fast VM restart.
> >
> > On 11/26/13 6:54 AM, "David Nalley" <david@gnsa.us> wrote:
> >
> >> Hi Koushik:
> >>
> >> Thanks for the reply - a few followup comments inline. I look forward
> >> to seeing this work.
> >>
> >> Other folks: please read the entire thread and the links from
> >> Koushik; there's a planned deprecation here.
> >>
> >> --David
> >>
> >> On Mon, Nov 25, 2013 at 2:38 AM, Koushik Das <koushik.das@citrix.com>
> >> wrote:
> >>> Thanks for the comments David. See inline.
> >>>
> >>> -Koushik
> >>>
> >>> On 22-Nov-2013, at 7:31 PM, David Nalley <david@gnsa.us> wrote:
> >>>
> >>>> 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.
> >>>
> >>> [Koushik] Are you suggesting that as part of the upgrade process,
> >>> all impacted VMs should be automatically updated? If so, yes it can be
> done.
> >>> For now I am keeping it manual, in future the process can be automated.
> >>>
> >>
> >> Why keeping it manual now? Actually let me rephrase - I can
> >> understand why someone might not want things changed automagically
> >> (as an admin I'd want nothing changed by default, but changed if I
> >> cared about it in some automated fashion) Is there a reason we would
> >> not include some functionality to let the operator automatically
> >> change this on some subset or all of the machines in an automated
> fashion?
> >>
> >>>>
> >>>> 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.
> >>>
> >>> [Koushik] That's the plan going forward. For the next release both
> >>> options will be there. Maybe post that the custom HA solution can be
> >>> removed for XS 6.2 and above.
> >>>
> >>>>
> >>
> >> Please make sure that the deprecation is explicitly called out. E.g
> >> will be present but deprecated in 4.4 and removed in 4.5; and let's
> >> make sure a doc bug gets filed when this is ready for merge.
> >>
> >> --David
> >


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