Bug 508662
| Summary: | RFE: qemu: support qemu snapshot=on with <transient/> disk XML | ||
|---|---|---|---|
| Product: | [Community] Virtualization Tools | Reporter: | Jan ONDREJ <ondrejj> |
| Component: | libvirt | Assignee: | Libvirt Maintainers <libvirt-maint> |
| Status: | CLOSED CURRENTRELEASE | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | low | ||
| Version: | unspecified | CC: | berrange, bloch, clalance, crobinso, eblake, ildar.mulyukov, itamar, jrb, jtomko, mzhan, veillard, virt-maint, von, xen-maint |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2020-11-03 15:01:34 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | |||
| Bug Blocks: | 636033, 1040068 | ||
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Description
Jan ONDREJ
2009-06-29 11:47:05 UTC
There are other options, which can be useful too, for example these:
"snapshot=snapshot"
snapshot is "on" or "off" and allows to enable snapshot for
given drive (see -snapshot).
"cache=cache"
cache is "none", "writeback", or "writethrough" and controls
how the host cache is used to access block data.
"boot=boot"
boot if "on" enables extboot for a given drive so it can be
used as a boot drive.
Moving this to libvirt's upstream bug tracker - it's a common request, but there are no immediate plans to implement it (Not, cache= and boot= are already available through libvirt) The XML is in place as of 0.9.5 (the <transient/> attribute of a <disk> in domain xml), but has not yet been wired up to qemu. *** Bug 832194 has been marked as a duplicate of this bug. *** the way #1 worked well until recently. The config part for it:
> <qemu:commandline>
> <qemu:arg value='-snapshot'/>
> </qemu:commandline>
But last upgrade of libvirt&qemu brought `-snapshot` option ignored by qemu. Hence would someone please
re-triage?
qemu bug reported: https://bugs.launchpad.net/qemu/+bug/1860759 (In reply to ildar.mulyukov from comment #6) > qemu bug reported: https://bugs.launchpad.net/qemu/+bug/1860759 Per the qemu team, it is intentional (albeit poorly documented) that -snapshot only works with -drive, not -snapshot. Libvirt should be implementing support for the <transient/> tag per <disk> element; absent that, you may still be able to get your command-line passthrough hack of passing -snapshot by telling libvirt to use -drive instead of -blockdev. I'm not sure of the trick, but know that Peter made the choice between old or new configurable in case we encountered problems with -blockdev; this would be one such case to use the trick. Eric, thanks for the hint. Excuse me, but Peter - who? How can we know more about the trick as we (users) are screwed in the situation when `<transient/>` isn't yet implemented and the old trick with `<qemu:arg/>` have no effect anymore? Thanks in advance! See: https://libvirt.org/drvqemu.html#xmlnsfeatures <qemu:del capability='blockdev'/> should do the trick Perfectly right, thanks a lot, Ján! (In reply to ildar.mulyukov from comment #8) > Eric, thanks for the hint. Excuse me, but Peter - who? Sorry, Peter Krempa. But I see Jan answered in the meantime. Support for <transient/> in QEMU was introduced in release 6.9.0 per https://www.redhat.com/archives/libvir-list/2020-October/msg00006.html |