because it might still run or be restarted on the unreachable host. On Fri, Jun 18, 2021 at 12:06 PM Jeremy Hansen <jer...@skidrow.la> wrote:
> Just seems strange. If I have centralized storage and I can migrate live > vm’s, why wouldn’t I be able to take the risk to migrate a dead vm guest, > as in, just start it on another available host and start it and consider it > migrated. If the original vm host happens to come back up and the instance > has already migrated, just leave it alone. Seems like that would go a long > way for high availability. I assume i/o fencing becomes an issue. I’d > prefer some kind of hook so if a VM host seems dead beyond, say, 5 minutes, > i/o fence it by triggering a power off from the PDU and bring up the VM > guests somewhere else. > > -jeremy > > > > On Jun 18, 2021, at 2:42 AM, Daan Hoogland <daan.hoogl...@gmail.com> > wrote: > > > > :D > > I'm sorry, when your bike is broken you have to walk. detection if the > > exact situation is the issue here, good luck in your search! > > > > On Fri, Jun 18, 2021 at 11:31 AM Jeremy Hansen <jer...@skidrow.la> > wrote: > > > >> I guess I’m looking for a recovery scenario where the dead vm host is > not > >> coming back, failed disk, caught on fire, and a reboot isn’t going to > help. > >> > >> Thanks > >> > >>> On Jun 18, 2021, at 1:41 AM, Daan Hoogland <daan.hoogl...@gmail.com> > >> wrote: > >>> > >>> Jemery, > >>> If you don't have IPMI then ACS can not know for sure that the VM won't > >>> come back. If it comes back the VM would be running twice and this must > >> be > >>> prevented at all costs. Maybe I am missing some functionality, and > >> someone > >>> else can give additional options. > >>> > >>>> On Fri, Jun 18, 2021 at 10:21 AM Jeremy Hansen <jer...@skidrow.la> > >> wrote: > >>>> > >>>> I pasted that from the documentation. My end goal is if a VM host > dies > >>>> completely and I’m not available to fix it, I would like the VM guests > >> that > >>>> were running on the failed host to automatically migrate to an > >> available VM > >>>> host so the guest instances continue to run. Perhaps that’s not how > it > >>>> works. The hosts I’m using for testing do not have any kind of IPMI > >>>> supported out of band management. They do have network enabled PDUs > but > >>>> let’s just say the VM host is gone completely. How do I get the VM > >> guests > >>>> that were running on the failed host back up and running without my > >>>> intervention? I guess I wrongly assumed Cloudstack would handle this > >> case > >>>> by just starting the VMs on another available host machine after some > >> kind > >>>> of failed heartbeat threshold. > >>>> > >>>> Thanks > >>>> -jeremy > >>>> > >>>>> On Jun 18, 2021, at 1:09 AM, Daan Hoogland <daan.hoogl...@gmail.com> > >>>> wrote: > >>>>> > >>>>> Jeremy, > >>>>> I don't fully understand your question. You say you are interested in > >>>>> HostHA specifically but then you ask about restarting VMs when a host > >>>> dies. > >>>>> This would not be safe as we can't be sure a host really dies unless > >> you > >>>>> have HostHA enabled. Consequently you can't guarantee the VM won't > >>>> suddenly > >>>>> re-apear when the host is seen running again. So keep these things > >>>>> separated. > >>>>> HostHA is for rebooting suspect hosts, not for moving VMs around. I > am > >>>> not > >>>>> aware of the connection between the two, that you seem to look for. > >>>>> > >>>>> > >>>>> On Fri, Jun 11, 2021 at 11:03 AM Jeremy Hansen <jer...@skidrow.la> > >>>> wrote: > >>>>> > >>>>>> > >>>>>> I’m trying to play with HA. I’ve enabled it via the interface but > the > >>>> HA > >>>>>> state is labeled as Ineligible. > >>>>>> > >>>>>> I’m specifically interested in this: > >>>>>> > >>>>>> HA for Hosts > >>>>>> > >>>>>> The user can specify a virtual machine as HA-enabled. By default, > all > >>>>>> virtual router VMs and Elastic Load Balancing VMs are automatically > >>>>>> configured as HA-enabled. When an HA-enabled VM crashes, CloudStack > >>>> detects > >>>>>> the crash and restarts the VM automatically within the same > >> Availability > >>>>>> Zone. HA is never performed across different Availability Zones. > >>>> CloudStack > >>>>>> has a conservative policy towards restarting VMs and ensures that > >> there > >>>>>> will never be two instances of the same VM running at the same time. > >> The > >>>>>> Management Server attempts to start the VM on another Host in the > same > >>>>>> cluster. > >>>>>> > >>>>>> > >>>>>> My assumption is if a VM Host dies, whatever guests that were > running > >> on > >>>>>> that host would automatically move to an available VM host. Maybe > I’m > >>>>>> misinterpreting. > >>>>>> > >>>>>> Thanks > >>>>>> -jeremy > >>>>>> > >>>>> > >>>>> > >>>>> -- > >>>>> Daan > >>>> > >>>> > >>> > >>> -- > >>> Daan > >> > >> > > > > -- > > Daan > > -- Daan
