Bug 1892805
| Summary: | NVDIMM: qemu warning is logged when running VM with NVDIMM device. | ||||||||||
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| Product: | [oVirt] ovirt-engine | Reporter: | Nisim Simsolo <nsimsolo> | ||||||||
| Component: | BLL.Virt | Assignee: | Milan Zamazal <mzamazal> | ||||||||
| Status: | CLOSED WONTFIX | QA Contact: | Nisim Simsolo <nsimsolo> | ||||||||
| Severity: | low | Docs Contact: | |||||||||
| Priority: | unspecified | ||||||||||
| Version: | 4.4.3.8 | CC: | ahadas, bugs, nsimsolo | ||||||||
| Target Milestone: | --- | Flags: | pm-rhel:
ovirt-4.5?
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| Target Release: | --- | ||||||||||
| Hardware: | Unspecified | ||||||||||
| OS: | Unspecified | ||||||||||
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| Fixed In Version: | Doc Type: | If docs needed, set a value | |||||||||
| Doc Text: | Story Points: | --- | |||||||||
| Clone Of: | Environment: | ||||||||||
| Last Closed: | 2022-01-09 15:54:25 UTC | Type: | Bug | ||||||||
| Regression: | --- | Mount Type: | --- | ||||||||
| Documentation: | --- | CRM: | |||||||||
| Verified Versions: | Category: | --- | |||||||||
| oVirt Team: | Virt | RHEL 7.3 requirements from Atomic Host: | |||||||||
| Cloudforms Team: | --- | Target Upstream Version: | |||||||||
| Embargoed: | |||||||||||
| Bug Depends On: | 1855336 | ||||||||||
| Bug Blocks: | |||||||||||
| Attachments: |
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Description
Nisim Simsolo
2020-10-29 16:50:51 UTC
Created attachment 1725110 [details]
engine.log
Created attachment 1725111 [details]
vdsm.log
Created attachment 1725112 [details]
qemu log
According to QEMU documentation, https://github.com/qemu/qemu/blob/2c6605389c1f76973d92b69b85d40d94b8f1092c/docs/nvdimm.txt#L153, host-crash-proof persistence is available only when using a DAX backing device: Though QEMU supports multiple types of vNVDIMM backends on Linux, the only backend that can guarantee the guest write persistence is: A. DAX device (e.g., /dev/dax0.0, ) or B. DAX file(mounted with dax option) ... If these conditions are not satisfied i.e. if either 'pmem' or 'share' are not set, if the backend file does not support DAX or if MAP_SYNC is not supported by the host kernel, write persistence is not guaranteed after a system crash. For compatibility reasons, these conditions are ignored if not satisfied. That means that in this case, where fsdax mode was probably used on the host NVDIMM device, the persistence cannot be guaranteed (and it cannot be currently guaranteed at all, since DAX host device mode doesn't work due to Bug 1855336). Note that it concerns only a host crash, as cited above and in the warning, not a regular flow. We should document this persistence limitation. Arik, I'll update the feature page, how to handle the downstream documentation? Should I file a doc bug? (In reply to Milan Zamazal from comment #4) > We should document this persistence limitation. Arik, I'll update the > feature page, how to handle the downstream documentation? Should I file a > doc bug? Yes please Documentation bug: BZ 1894067 Just waiting for the bugs this one depends on. Closing as per bz 1855336 |