Cool, more fuel to get a proper section on HA. Sent from my iPhone
On Feb 27, 2013, at 11:51 PM, Nitin Mehta <nitin.me...@citrix.com> wrote: > I was searching for this document which used to be on docs.cloudstack.org > but couldn't find it. Thanks for pointing this one. > > On 28/02/13 1:12 PM, "Mice Xia" <mice_...@tcloudcomputing.com> wrote: > >> 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 this document is a little outdated, but the concepts and overall workflow 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 >>>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>> >>>>>> >>>>>> >>> >
