There is a document describing HA in details, you can check it on: http://people.apache.org/~mice/CloudStackHighAvailability.pdf
this document is a little outdated, but the concepts and overall workflow still apply. Regards Mice -----Original Message----- From: Kelceydamage@bbits [mailto:kel...@bbits.ca] Sent: Thursday, February 28, 2013 3:24 PM To: cloudstack-dev@incubator.apache.org Cc: cloudstack-dev@incubator.apache.org Subject: Re: HA question I could get one started. I've saved this thread, and I'll try to get some stuff up in the next couple days. Sent from my iPhone On Feb 27, 2013, at 10:57 PM, Nitin Mehta <nitin.me...@citrix.com> wrote: > Kelcey - Would you be willing to put a HA wiki ? I promise to > volunteer :) with whatever I know > > On 28/02/13 12:16 PM, "Kelceydamage@bbits" <kel...@bbits.ca> wrote: > >> This is turning out to be a great discussion to have. Now I get that >> CloudStack HA is purely handled by the management/orchestration >> engine and only if VM is tagged(which I knew). But what is good to >> find out is that it does not involve underlying hypervisor specific >> HA modules(except perhaps VMware). Incidentally VMwares HA mechanism >> is also called storage >> heartbeat(5.x+) but it uses hypervisor modules as well. >> >> I do agree with Ahmad that it might be worth looking into expanding >> our HA suite to support hypervisor specific HA modules as an override >> to the default CS HA. >> >> There has not been too many HA discussions on the mailing list, and >> by the looks of it we were all under slightly different impressions. >> >> Thanks again for the good discussion. >> >> Sent from my iPhone >> >> On Feb 27, 2013, at 9:48 PM, Ahmad Emneina <aemne...@gmail.com> wrote: >> >>> I would imagine it's best to leverage on the underlying hypervisors' >>> HA mechanisms, configured oud-of-band of cloudstack. I find >>> cloudstacks implementation a little laggy compared to the paid for variety. >>> CloudStack >>> does a well enough job to figure out which host the vm eventually >>> lands on. >>> >>> >>> On Wed, Feb 27, 2013 at 9:37 PM, Mice Xia >>> <mice_...@tcloudcomputing.com>wrote: >>> >>>> Currently for xenserver/KVM, Cloudstack uses 'storage heartbeat' to >>>> detect whether it should start HA, i.e. agent resides on >>>> xenserver/KVM periodically writes a timestamp on shared storage, if >>>> host network pingTimeOut happens, Cloudstack will investigate if >>>> 'storage heartbeat' >>>> timeout and if that's the case HA job will be launched for HA >>>> enabled VMs on the host. >>>> >>>> It's a simplified procedure, HA implementation involves delta sync/ >>>> investigators and fencers. >>>> >>>> -Mice >>>> >>>> -----Original Message----- >>>> From: Sanjeev Neelarapu [mailto:sanjeev.neelar...@citrix.com] >>>> Sent: Thursday, February 28, 2013 1:21 PM >>>> To: cloudstack-dev@incubator.apache.org; kdam...@apache.org >>>> Subject: RE: HA question >>>> >>>> Hi Hari, >>>> >>>> AFAIK, in CloudStack if a host crashes CloudStack would detect the >>>> host as down after pingTimeout interval. >>>> CloudStack does not reduce the available capacity because the host >>>> capacity values are not removed from op_host_capacity table. It >>>> assumes the host down is a temporary issue. >>>> >>>> Thanks, >>>> Sanjeev >>>> >>>> -----Original Message----- >>>> From: Hari Kannan [mailto:hari.kan...@citrix.com] >>>> Sent: Thursday, February 28, 2013 10:36 AM >>>> To: kdam...@apache.org; cloudstack-dev@incubator.apache.org >>>> Subject: RE: HA question >>>> >>>> Hi Kelcey, >>>> >>>> At the risk of stating the obvious, I just wish to re-iterate my >>>> earlier point - with CloudStack, HA is for VM, not for host. That >>>> is different than VMware's HA in someways - in VMware, if a cluster >>>> is HA, when any host crashes, all VMs on that host will be >>>> restarted on a different host. >>>> With >>>> cloudstack, only VMs that are HA enabled will be restarted. >>>> >>>> At least, that is the way I understand this.. >>>> >>>> I also wonder what happens in CloudStack if a host crashes (assume >>>> there were no VMs on it) - would CloudStack detect this host is >>>> down and reduce the available capacity? >>>> >>>> Hari >>>> >>>> -----Original Message----- >>>> From: Kelcey Damage (BT) [mailto:kel...@backbonetechnology.com] On >>>> Behalf Of kdam...@apache.org >>>> Sent: Wednesday, February 27, 2013 8:51 PM >>>> To: cloudstack-dev@incubator.apache.org >>>> Cc: Hari Kannan >>>> Subject: RE: HA question >>>> >>>> So it's safe to conclude that HA while enabled on the host(As in >>>> the module), must be available cluster wide(uniform cluster). This >>>> is how VMware and others operate. >>>> >>>> Thanks all. >>>> >>>> -Kelcey >>>> >>>> >>>>> -----Original Message----- >>>>> From: Sateesh Chodapuneedi >>>>> [mailto:sateesh.chodapune...@citrix.com] >>>>> Sent: Wednesday, February 27, 2013 8:46 PM >>>>> To: cloudstack-dev@incubator.apache.org >>>>> Cc: Hari Kannan >>>>> Subject: RE: HA question >>>>> >>>>> For VMware, CloudStack uses native HA provided by VMware. >>>>> VMware provides HA at the level of cluster. >>>>> >>>>> Regards, >>>>> Sateesh >>>>> >>>>>> -----Original Message----- >>>>>> From: Nitin Mehta [mailto:nitin.me...@citrix.com] >>>>>> Sent: 28 February 2013 10:13 >>>>>> To: cloudstack-dev@incubator.apache.org >>>>>> Cc: Hari Kannan >>>>>> Subject: Re: HA question >>>>>> >>>>>> CS has its own HA logic and doesn't use the native HA of the HV >>>>>> and so the question for enabling the HA for hosts doesn't arise. >>>>>> This is true >>>> for XS. >>>>>> For Vmware and KVM, I will let the guru's speak :) >>>>>> >>>>>> On 28/02/13 9:55 AM, "kdam...@apache.org" <kdam...@apache.org> >>>>> wrote: >>>>>> >>>>>>> Thanks that¹s awesome, but not quite the answer I was looking for. >>>>>>> >>>>>>> To better phrase my question, if the cluster is the basic unit >>>>>>> of availability, when hosts are enabled for HA, must all hosts >>>>>>> in the cluster be enabled? Or can the cluster exist with a >>>>>>> non-uniform structure, having only some hosts enabled for HA? >>>>>>> >>>>>>> You partially answered it with the special reserve HA hosts, but >>>>>>> I'm looking more in terms of general use. >>>>>>> >>>>>>> Thanks >>>>>>> >>>>>>> -kelcey >>>>>>> >>>>>>> >>>>>>>> -----Original Message----- >>>>>>>> From: Hari Kannan [mailto:hari.kan...@citrix.com] >>>>>>>> Sent: Wednesday, February 27, 2013 8:21 PM >>>>>>>> To: cloudstack-dev@incubator.apache.org >>>>>>>> Subject: RE: HA question >>>>>>>> >>>>>>>> Hi Kelsey, >>>>>>>> >>>>>>>> HA is at 2 levels VMs can be marked HA. In addition, you can >>>>>>>> mark some hosts as reserved for ³Dedicated² HA hosts. Quoting >>>>>>>> from the manual, the dedicated HA option is set through a >>>>>>>> special host tag when the host is created. >>>>>>>> To allow the administrator to dedicate hosts to only HA-enabled >>>>>>>> VMs, set the global configuration variable ha.tag to the >>>>>>>> desired tag (for example, "ha_host"), and restart the Management >>>>>>>> Server. >>>>>>>> Enter the value in the Host Tags field when adding the host(s) >>>>>>>> that you want to dedicate to HA-enabled VMs. >>>>>>>> >>>>>>>> Hari >>>>>>>> >>>>>>>> From: Kelcey Damage (BT) [mailto:kel...@backbonetechnology.com] >>>>>>>> Sent: Wednesday, February 27, 2013 8:00 PM >>>>>>>> To: CloudStack dev list >>>>>>>> Subject: RE: HA question >>>>>>>> >>>>>>>> Hi, >>>>>>>> >>>>>>>> I can¹t remember, do we enable HA on a per host basis, or on a >>>>>>>> per cluster basis? >>>>>>>> >>>>>>>> Thanks. >>>>>>>> >>>>>>>> [cid:image001.png@01CE1524.FA0D61B0]Kelcey Damage >>>>>>>> Infrastructure Systems Architect >>>>>> >>>>>>> www.backbonetechnology.com<http://www.backbonetechnology.com/> >>>>>>>> --------------------------------------------------------------- >>>>>>>> ---- >>>>>>>> - >>>>>>>> ----- >>>>>> >>>>>>> kel...@backbonetechnology.com<mailto:kelcey@backbonetechnology.c >>>>>>> o >>>>> m >>>>>>>>> >>>>>>>> >>>>>>>> address: 55 East 7th Ave, Vancouver, BC, V5T 1M4 >>>>>>>> tel: +1 604 713 8560 ext:114 >>>>>>>> fax: +1 604 605 0964 >>>>>>>> skype: kelcey.damage >>>>>>>> >>>>>>> >>>>>>> >>>> >>>> >>>> >
