On Tue, Feb 2, 2021 at 1:57 PM Vojtech Juranek <[email protected]> wrote:
> On Tuesday, 2 February 2021 11:37:01 CET Andrea Chierici wrote: > > Hi, > > I am trying to configure high availability on a critical VM. My ovirt > > version is 4.3.10.4-1.el7. > > My question is about the best settings to specify, since it's not > > completely clear to me how they influence the availability. > > > > What I want is simply to have a specific machine ALWAYS running, or at > > least, to be available as much as possible. I have no special > > requirements on the VM, if it goes down, simply restarting it is fine. > > > > Here is my current setting. Is it good or I'd better chage anything? > > you may want to configure VM lease. If you don't do so, in case of split > brain, there can be two VMs running and accessing the same storage, > leading to > the data corruption. With VM leases this cannot happen - only one VM can > access the storage. To speed up the switch, you may want to configure also > watchdog. But there can be use cases (e.g. stateless server which just > forwards received packet somewhere) where leases are not needed or not > using > them won't cause any harm. See [1] for more details. > > [1] https://www.ovirt.org/develop/ha-vms.html Indeed, configuring a VM lease and a watchdog device can be useful. Not only that a VM lease can generally prevent split brains but in case the host that the VM runs on becomes non-responsive, the system would automatically try to restart the VM elsewhere (otherwise, the system waits for a confirmation from the admin that the host is down which can take time, and yes, if the VM still runs on the non-responsive host can lead to a split-brain). The watchdog device identifies problems from within the guest that are otherwise hard to identify from outside of the virtual machine. Richard Jones wrote a nice post about the watchdog device few years ago [2] [2] https://rwmj.wordpress.com/2010/03/03/what-is-a-watchdog/ > > > > > > > > Thanks, > > Andrea > > _______________________________________________ > Users mailing list -- [email protected] > To unsubscribe send an email to [email protected] > Privacy Statement: https://www.ovirt.org/privacy-policy.html > oVirt Code of Conduct: > https://www.ovirt.org/community/about/community-guidelines/ > List Archives: > https://lists.ovirt.org/archives/list/[email protected]/message/IYHLDVK7UNFBHAT7ZQ3J7LIJSS24AZ5B/ >
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