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 > >> >> > >> > > >> > > > >
