Change in vdsm[master]: virt: vm: Replace update time migration TODO
mzamazal at redhat.com
mzamazal at redhat.com
Tue Dec 15 09:56:39 UTC 2015
Milan Zamazal has uploaded a new change for review.
Change subject: virt: vm: Replace update time migration TODO
......................................................................
virt: vm: Replace update time migration TODO
As discussed in https://gerrit.ovirt.org/49212, we are not going to
update time on the guest after live migration. So we replace the
corresponding TODO with an explanation comment.
Change-Id: Ic2f6419825973680b2188ffa34e80994a1fbdb18
Signed-off-by: Milan Zamazal <mzamazal at redhat.com>
---
M vdsm/virt/vm.py
1 file changed, 11 insertions(+), 5 deletions(-)
git pull ssh://gerrit.ovirt.org:29418/vdsm refs/changes/99/50499/1
diff --git a/vdsm/virt/vm.py b/vdsm/virt/vm.py
index b375cd0..28c0019 100644
--- a/vdsm/virt/vm.py
+++ b/vdsm/virt/vm.py
@@ -2831,11 +2831,17 @@
hooks.after_device_migrate_destination(
dev._deviceXML, self.conf, dev.custom)
- # TODO: _syncGuestTime() should be called here as it is in
- # restore_state path. But there may be some issues with the call
- # such as blocking for some time when qemu-guest-agent is not
- # running in the guest. We'd like to discuss them more before
- # touching migration.
+ # We refrain from syncing time in this path. There are two basic
+ # reasons:
+ # 1. The jump change in the time (as performed by QEMU) may cause
+ # undesired effects like unnecessary timeouts, false alerts
+ # (think about logging excessive SQL command execution times),
+ # etc. This is not what users expect when performing live
+ # migrations.
+ # 2. The user can simply run NTP on the VM to keep the time right
+ # and smooth after migrations. On the contrary to suspensions,
+ # there is no danger of excessive delays preventing NTP from
+ # operation.
if 'guestIPs' in self.conf:
del self.conf['guestIPs']
--
To view, visit https://gerrit.ovirt.org/50499
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Gerrit-MessageType: newchange
Gerrit-Change-Id: Ic2f6419825973680b2188ffa34e80994a1fbdb18
Gerrit-PatchSet: 1
Gerrit-Project: vdsm
Gerrit-Branch: master
Gerrit-Owner: Milan Zamazal <mzamazal at redhat.com>
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