Re: [ovirt-users] Actual downtime during migration?
On Fri, Jan 27, 2017 at 2:59 PM, Doug Inghamwrote: >> its memory resynchronised one last time > > Actually, thinking about it, rather than diffing all of the memory on the > first host to resync it at the last moment, the hypervisor probably > simultaneously copies the current state of memory & uses copy-on-write (COW) > to write all new transactions to both hosts. > Only a technical difference, but it'd greatly reduce how long the VM needs > to be paused to complete a full sync. Is this in 4.1? See also: http://www.ovirt.org/develop/release-management/features/migration-enhancements/ Best, -- Didi ___ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
Re: [ovirt-users] Actual downtime during migration?
> > its memory resynchronised one last time > Actually, thinking about it, rather than diffing *all* of the memory on the first host to resync it at the last moment, the hypervisor probably simultaneously copies the current state of memory & uses copy-on-write (COW) to write all new transactions to both hosts. Only a technical difference, but it'd greatly reduce how long the VM needs to be paused to complete a full sync. -- Doug ___ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
Re: [ovirt-users] Actual downtime during migration?
Hi Gianluca, My educated guess...When you live migrate a VM, its state in memory is copied over to the new host, but the VM still remains online during this period to minimise downtime. Once its state in memory is fully copied to the new host, the VM is paused on the original host, its memory resynchronised one last time & then brought up on the new host. So whilst the entire process took 39 seconds, actual downtime was only 133ms. Doug On 27 January 2017 at 09:34, Gianluca Cecchiwrote: > Hello, > I was testing put host into maintenance on 4.0.6, with 1 VM running. > It correctly completes the live migration of the VM and I see this event > in pane: > > Migration completed (VM: ol65, Source: ovmsrv06, Destination: ovmsrv05, > Duration: 39 seconds, Total: 39 seconds, Actual downtime: 133ms) > > What is considered as "Actual downtime"? > > Thanks, > Gianluca > > > ___ > Users mailing list > Users@ovirt.org > http://lists.ovirt.org/mailman/listinfo/users > > -- Doug ___ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
[ovirt-users] Actual downtime during migration?
Hello, I was testing put host into maintenance on 4.0.6, with 1 VM running. It correctly completes the live migration of the VM and I see this event in pane: Migration completed (VM: ol65, Source: ovmsrv06, Destination: ovmsrv05, Duration: 39 seconds, Total: 39 seconds, Actual downtime: 133ms) What is considered as "Actual downtime"? Thanks, Gianluca ___ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users