Bug 1643510

Summary:	Wrong default cache mode for ephemeral disks
Product:	Container Native Virtualization (CNV)	Reporter:	Marcin Franczyk <mfranczy>
Component:	Virtualization	Assignee:	Marcin Franczyk <mfranczy>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Denys Shchedrivyi <dshchedr>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	1.3	CC:	cnv-qe-bugs, fdeutsch, ipinto, mfranczy, ncredi
Target Milestone:	---
Target Release:	1.3
Hardware:	All
OS:	All
Whiteboard:
Fixed In Version:	kubevirt-0.9.4-2.gd763ed8.6e00282 cnv-libvirt-container-v1.3.0-3 virt-api-container-v1.3.0-11 virt-controller-container-v1.3.0-13 virt-handler-container-v1.3.0-12 virt-launcher-container-v1.3.0-13	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-01-08 14:27:09 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Marcin Franczyk 2018-10-26 12:23:14 UTC

Description of problem:
Because of a bug in the code, driver cache mode for ephemeral disks is set to 'writethrough' (always), when fs supports direct I/O it should be set to 'none'.

Version-Release number of selected component (if applicable):
1.3.0

How reproducible:


Steps to Reproduce:
1.
2.
3.

Actual results:


Expected results:
If possible driver cache mode should be set to 'none'.

Additional info:
Bugfix has been prepared, link to PR https://github.com/kubevirt/kubevirt/pull/1651

Comment 1 Marcin Franczyk 2018-11-05 10:26:56 UTC

PR has been merged, it might be tested by adding an ephemeral disk to a VM and by checking libvirt XML we should see cache 'none' on fs which supports direct I/O.

Comment 2 Fabian Deutsch 2018-11-05 14:18:41 UTC

Nelly, can we get qa_ack+?

Comment 6 Denys Shchedrivyi 2018-11-08 18:27:58 UTC

Verified on:
$ virtctl version
Client Version: version.Info{GitVersion:"v0.9.4", GitCommit:"6e0028292ab269f4b4b5d98b1870ca5b84a47b10", GitTreeState:"clean", BuildDate:"2018-11-07T17:08:16Z", GoVersion:"go1.9.4", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{GitVersion:"v1.3.0-11-1-g3f367f7", GitCommit:"78435f76c79c97c4491fd7c0549744633c98a53d", GitTreeState:"clean", BuildDate:"2018-11-08T14:55:47Z", GoVersion:"go1.9.4", Compiler:"gc", Platform:"linux/amd64"}

By default driver cache mode is set to 'none', when fs supports direct I/O