[nova] [libvirt] About libvirt autoconverge
Do you enable auto-converge for nova instance live migration on all production hypervisor hosts?
Auto-converge will slows down instance CPU until the memory copy process is faster than the instance's memory writes so i test on my system and the instance can be timeout some packets before it was migrated completely,
Enable post-copy, I use in my system because I see that instance won't be timeout when it was live migrated but:
Possible downsides:
When the network connection between source and destination is interrupted, page faults cannot be resolved anymore, and the virtual machine is rebooted. Post-copy may lead to an increased page fault rate during migration, which can slow the instance down
In my case, I don't see impacts with this option till now.
https://docs.openstack.org/nova/yoga/admin/live-migration-usage.html
Nguyen Huu Khoi
On Tue, Oct 17, 2023 at 1:08 PM hai wu haiwu.us@gmail.com wrote:
Do you enable auto-converge for nova instance live migration on all production hypervisor hosts?
Thanks. yeah I am not sure if I want to use the post-copy feature. A few packets timeout is acceptable I think.
Could we say that with 'live_migration_permit_auto_converge=true' enabled for nova.conf, it might ONLY cause instance slow-down during its live migration process, ONLY when it detects that the instance's memory writes are too fast to keep up with?
This means it won't cause instance slow-down when there's no live migration going on?
Hai
On Tue, Oct 17, 2023 at 2:43 AM Nguyễn Hữu Khôi nguyenhuukhoinw@gmail.com wrote:
Auto-converge will slows down instance CPU until the memory copy process is faster than the instance's memory writes so i test on my system and the instance can be timeout some packets before it was migrated completely,
Enable post-copy, I use in my system because I see that instance won't be timeout when it was live migrated but:
Possible downsides:
When the network connection between source and destination is interrupted, page faults cannot be resolved anymore, and the virtual machine is rebooted. Post-copy may lead to an increased page fault rate during migration, which can slow the instance down
In my case, I don't see impacts with this option till now.
https://docs.openstack.org/nova/yoga/admin/live-migration-usage.html
Nguyen Huu Khoi
On Tue, Oct 17, 2023 at 1:08 PM hai wu haiwu.us@gmail.com wrote:
Do you enable auto-converge for nova instance live migration on all production hypervisor hosts?
Yes. It is only when we mỉgate instance and dont impact others
On Tue, Oct 17, 2023, 8:23 PM hai wu haiwu.us@gmail.com wrote:
Thanks. yeah I am not sure if I want to use the post-copy feature. A few packets timeout is acceptable I think.
Could we say that with 'live_migration_permit_auto_converge=true' enabled for nova.conf, it might ONLY cause instance slow-down during its live migration process, ONLY when it detects that the instance's memory writes are too fast to keep up with?
This means it won't cause instance slow-down when there's no live migration going on?
Hai
On Tue, Oct 17, 2023 at 2:43 AM Nguyễn Hữu Khôi nguyenhuukhoinw@gmail.com wrote:
Auto-converge will slows down instance CPU until the memory copy
process is faster than the instance's memory writes so i test on my system and the instance can be timeout some packets before it was migrated completely,
Enable post-copy, I use in my system because I see that instance won't
be timeout when it was live migrated but:
Possible downsides:
When the network connection between source and destination is
interrupted, page faults cannot be resolved anymore, and the virtual machine is rebooted.
Post-copy may lead to an increased page fault rate during migration,
which can slow the instance down
In my case, I don't see impacts with this option till now.
https://docs.openstack.org/nova/yoga/admin/live-migration-usage.html
Nguyen Huu Khoi
On Tue, Oct 17, 2023 at 1:08 PM hai wu haiwu.us@gmail.com wrote:
Do you enable auto-converge for nova instance live migration on all production hypervisor hosts?
Ok, thanks for the clarification.
On Tue, Oct 17, 2023 at 8:26 AM Nguyễn Hữu Khôi nguyenhuukhoinw@gmail.com wrote:
Yes. It is only when we mỉgate instance and dont impact others
On Tue, Oct 17, 2023, 8:23 PM hai wu haiwu.us@gmail.com wrote:
Thanks. yeah I am not sure if I want to use the post-copy feature. A few packets timeout is acceptable I think.
Could we say that with 'live_migration_permit_auto_converge=true' enabled for nova.conf, it might ONLY cause instance slow-down during its live migration process, ONLY when it detects that the instance's memory writes are too fast to keep up with?
This means it won't cause instance slow-down when there's no live migration going on?
Hai
On Tue, Oct 17, 2023 at 2:43 AM Nguyễn Hữu Khôi nguyenhuukhoinw@gmail.com wrote:
Auto-converge will slows down instance CPU until the memory copy process is faster than the instance's memory writes so i test on my system and the instance can be timeout some packets before it was migrated completely,
Enable post-copy, I use in my system because I see that instance won't be timeout when it was live migrated but:
Possible downsides:
When the network connection between source and destination is interrupted, page faults cannot be resolved anymore, and the virtual machine is rebooted. Post-copy may lead to an increased page fault rate during migration, which can slow the instance down
In my case, I don't see impacts with this option till now.
https://docs.openstack.org/nova/yoga/admin/live-migration-usage.html
Nguyen Huu Khoi
On Tue, Oct 17, 2023 at 1:08 PM hai wu haiwu.us@gmail.com wrote:
Do you enable auto-converge for nova instance live migration on all production hypervisor hosts?
participants (2)
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hai wu
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Nguyễn Hữu Khôi