On Monday, 2 August 2021 14:30:05 CEST Peter Krempa wrote: > On Mon, Aug 02, 2021 at 14:20:44 +0200, Vojtech Juranek wrote: > > Hi, > > as a follow-up of BZ #1883399 [1], we are reviewing vdsm VM migration > > flows and solve few follow-up bugs, e.g. BZ #1981079 [2]. I have couple > > of questions related to libvirt: > > > > * if we run disk extend during migration, it can happen that migration > > finishes sooner than disk extend. In such case we will try to set disk > > threshold on already stopped VM (we handle libvirt event that VM was > > stopper, but due to Python GIL there can be a delay between obtaining > > appropriate signal from libvirt and handling it). In such case we get > > libvirt > > VIR_ERR_OPERATION_INVALID when setting disk threshold. actually I was wrong here and the issue is actually caused by delay libvirt setBlockThreshold() call, form vdsm log: 2021-08-02 09:06:01,918-0400 WARN (mailbox-hsm/3) [virt.vm] (vmId='2dad9038-3e3a-4b5e-8d20-b0da37d9ef79') setting theshold using dom <vdsm.virt.virdomain.Notifying object at 0x7fd06610df28> (drivemonitor:122) [...] 2021-08-02 09:06:03,967-0400 WARN (libvirt/events) [virt.vm] (vmId='2dad9038-3e3a-4b5e-8d20-b0da37d9ef79') libvirt event Stopped detail 3 opaque None (vm:5657) [...] 2021-08-02 09:06:03,969-0400 WARN (mailbox-hsm/3) [virt.vm] (vmId='2dad9038-3e3a-4b5e-8d20-b0da37d9ef79') Domain not connected, skipping set block threshold for drive 'sdc' (drivemonitor:133) so it took about 2 second to libvirt setBlockThreshold() call to return and in meantime migration was finished and we get VIR_ERR_OPERATION_INVALID error from setBlockThreshold() call. What is the reason for this delay? Is this operation intentionally delayed until migration finishes? I posted relevant libvirt debug log on https://pastebin.com/YkdKYKM5 > > Is it safe to > > catch this exception and ignore it or it's thrown for various reasons and > > the root cause can be something else than stopped VM? > > The API to set the block trheshold level can return the following errors > including cases when it can happen: > > VIR_ERR_OPERATION_UNSUPPORTED <- unlikely new qemu supports it > VIR_ERR_INVALID_ARG <- disk was not found in VM definition > VIR_ERR_INTERNAL_ERROR <- on error from qemu > > Thus VIR_ERR_OPERATION_INVALID seems to be safe to ignore in your > specific case, while not ignoring others can be used to catch problems. thanks for your answer
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