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:kel...@backbonetechnology.co >>>> 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 >>>>>>> >>>>>> >>>>>> >>> >>> >>>
