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From: "DERUMIER, Alexandre" <alexandre.derumier@groupe-cyllene.com>
To: "pve-devel@lists.proxmox.com" <pve-devel@lists.proxmox.com>,
	"aderumier@odiso.com" <aderumier@odiso.com>,
	"f.ebner@proxmox.com" <f.ebner@proxmox.com>
Subject: Re: [pve-devel] [PATCH v4 qemu-server 2/2] remote-migration: add target-cpu && target-reboot params
Date: Mon, 23 Oct 2023 18:03:18 +0000	[thread overview]
Message-ID: <e572e2c518cc98cc383fb6a554a1324ed1dd2711.camel@groupe-cyllene.com> (raw)
In-Reply-To: <73e0a3a6-f978-ac24-5f6b-16af759ee209@proxmox.com>

Hi Fiona,


>>In case of 'restart' migration, we do want to start the VM anyways,
>>so
>>it's actually better, because we can catch config issues early :) Now
>>that I think about it, can we also just start the target VM in
>>prelaunch
>>mode (instead of incoming migration mode), do the NBD migration, shut
>>down the source VM, stop the NBD server and then resume the target?
>>That
>>would avoid the need to stop and start the target again. And
>>therefore
>>might be quite a bit less downtime.


I have done some tests, It's not possible currently to write to the
remote nbd without the --incoming migration flag and only -S



https://lists.gnu.org/archive/html/qemu-devel/2017-11/msg05700.html



nbd_add is throwing an error like

2023-10-23 18:45:51 [formationkvm1] VM 111 qmp command 'block-export-
add' failed - Permission conflict on node '#block524': permissions
'write' are both required by an unnamed block device (uses node
'#block524' as 'root' child) and unshared by block device 'drive-scsi0'
(uses node '#block524' as 'root' child).


Looking at the qemu code, the are some specific codepath in block when
the incoming flag is setup.


So I think the best way for now is to restart the target vm.



  parent reply	other threads:[~2023-10-23 18:03 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-28 14:45 [pve-devel] [PATCH v4 qemu-server 0/2] remote-migration: migration with different cpu Alexandre Derumier
2023-09-28 14:45 ` [pve-devel] [PATCH v4 qemu-server 1/2] migration: move livemigration code in a dedicated sub Alexandre Derumier
2023-10-09 11:25   ` Fiona Ebner
2023-09-28 14:45 ` [pve-devel] [PATCH v4 qemu-server 2/2] remote-migration: add target-cpu && target-reboot params Alexandre Derumier
2023-10-09 12:13   ` Fiona Ebner
2023-10-09 13:47     ` DERUMIER, Alexandre
2023-10-10  9:19       ` Fiona Ebner
2023-10-10 16:29         ` DERUMIER, Alexandre
2023-10-11  7:51           ` Fiona Ebner
2023-10-23 18:03         ` DERUMIER, Alexandre [this message]
2023-10-24  8:11           ` Fiona Ebner
2023-10-24 12:20             ` DERUMIER, Alexandre
2023-10-25  8:30               ` Fiona Ebner
2023-10-25 16:01                 ` DERUMIER, Alexandre
2023-10-27  9:19                   ` Fiona Ebner

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