I looked at the affinity group FS [1]. Based on what I understand with host affinity even CS HA won't work if the specific host fails. For cluster/pod affinity it will work though. Can someone confirm if this is the case?
For native XS HA since cluster is where HA gets configured, affinity groups can be realised at cluster level. For host affinity to work if the implicit assumption is to not make the VM HA enabled then there shouldn't be any issues. But there may be scenarios which won't be possible with native HA. Also in the FAQ section of [1] I see the following: "DRS? * This is applicable only for placement operations through CloudStack. This implementation is to only support scenarios where the HV does not do HA or DRS." This means that with Vmware (where there is native HA), affinity groups doesn't work. -Koushik [1] https://cwiki.apache.org/confluence/display/CLOUDSTACK/FS+-+Affinity-Anti-affinity+groups On 28-Nov-2013, at 3:29 AM, Alex Huang <alex.hu...@citrix.com<mailto:alex.hu...@citrix.com>> wrote: 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....@citrix.com<http://citrix.com>] Sent: Tuesday, November 26, 2013 10:51 PM To: <dev@cloudstack.apache.org<mailto: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.vit...@citrix.com<mailto:chiradeep.vit...@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" <da...@gnsa.us<mailto:da...@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....@citrix.com<mailto:koushik....@citrix.com>> wrote: Thanks for the comments David. See inline. -Koushik On 22-Nov-2013, at 7:31 PM, David Nalley <da...@gnsa.us<mailto:da...@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
