Bug 1546824

Summary:	Enable caching for disks with non-native IO
Product:	[oVirt] ovirt-engine	Reporter:	Arik <ahadas>
Component:	BLL.Virt	Assignee:	Arik <ahadas>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Polina <pagranat>
Severity:	high	Docs Contact:
Priority:	unspecified
Version:	4.2.1	CC:	bugs, pagranat
Target Milestone:	ovirt-4.2.2	Keywords:	Regression
Target Release:	---	Flags:	rule-engine: ovirt-4.2+ rule-engine: blocker+
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-03-29 11:10:19 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:

Description Arik 2018-02-19 16:44:54 UTC

The switch to engine XML broke the setting of cache for disks that are set with non-native IO.

Comment 1 Yaniv Kaul 2018-02-21 11:51:34 UTC

Currently, viodiskcache property does not work on 4.2 - setting Regression keyword.

Comment 2 Red Hat Bugzilla Rules Engine 2018-02-21 16:44:00 UTC

This bug report has Keywords: Regression or TestBlocker.
Since no regressions or test blockers are allowed between releases, it is also being identified as a blocker for this release. Please resolve ASAP.

Comment 3 Polina 2018-03-18 07:16:07 UTC

verified on build rhv-release-4.2.2-4-001.noarch

1. Create disk (Storage /Disks/Images) with profile nfs_0, Interface VirtIO.
2. Create VM with this disk.
3. Create Custom Property "viodiskcach = none"
3. On host run <virsh -r dumpxml 21>
    result:
    <ovirt-vm:custom>
        <ovirt-vm:viodiskcache>none</ovirt-vm:viodiskcache>
    </ovirt-vm:custom>
4. change the value of Custom Property "viodiskcach = writeback"
    result:
    <ovirt-vm:custom>
        <ovirt-vm:viodiskcache>writeback</ovirt-vm:viodiskcache>
    </ovirt-vm:custom>
5. change the value of Custom Property "viodiskcach = writethrough"
    result:
     <ovirt-vm:custom>
        <ovirt-vm:viodiskcache>writethrough</ovirt-vm:viodiskcache>
    </ovirt-vm:custom>

The same steps are performed with VirtIO-SCSI Interface disk.

Comment 4 Arik 2018-03-18 07:36:00 UTC

(In reply to Polina from comment #3)
> verified on build rhv-release-4.2.2-4-001.noarch
> 
> 1. Create disk (Storage /Disks/Images) with profile nfs_0, Interface VirtIO.
> 2. Create VM with this disk.
> 3. Create Custom Property "viodiskcach = none"
> 3. On host run <virsh -r dumpxml 21>
>     result:
>     <ovirt-vm:custom>
>         <ovirt-vm:viodiskcache>none</ovirt-vm:viodiskcache>
>     </ovirt-vm:custom>
> 4. change the value of Custom Property "viodiskcach = writeback"
>     result:
>     <ovirt-vm:custom>
>         <ovirt-vm:viodiskcache>writeback</ovirt-vm:viodiskcache>
>     </ovirt-vm:custom>
> 5. change the value of Custom Property "viodiskcach = writethrough"
>     result:
>      <ovirt-vm:custom>
>         <ovirt-vm:viodiskcache>writethrough</ovirt-vm:viodiskcache>
>     </ovirt-vm:custom>
> 
> The same steps are performed with VirtIO-SCSI Interface disk.

Polina, please verify that the cache is set in the 'driver' element of the 'disk'. It should be something like:
<disk ... >
 ...
 <driver cache="writethrough" ... />
 ...
</disk>

Comment 5 Polina 2018-03-18 08:27:44 UTC

yes, it appears under disk element:

    <disk type='file' device='cdrom'>
      <driver error_policy='report'/>
      <source startupPolicy='optional'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <alias name='ua-fc8fd256-bcf9-4994-bced-353c56e67334'/>
      <address type='drive' controller='0' bus='1' target='0' unit='0'/>
    </disk>
    <disk type='file' device='disk' snapshot='no'>
      <driver name='qemu' type='raw' cache='writeback' error_policy='stop' io='threads'/>
      <source file='/rhev/data-center/mnt/yellow-vdsb.qa.lab.tlv.redhat.com:_Compute__NFS_GE_compute-ge-3_nfs__0/8ac34f0b-b74a-48b7-bb81-9f5d112cf196/images/43ef6129-cc20-459a-bcce-fa5d9cff2962/a2510013-7c45-4b04-9c0a-93c83a3e9790'/>
      <backingStore/>
      <target dev='vda' bus='virtio'/>
      <serial>43ef6129-cc20-459a-bcce-fa5d9cff2962</serial>
      <alias name='ua-43ef6129-cc20-459a-bcce-fa5d9cff2962'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </disk>

Comment 6 Arik 2018-03-18 08:35:36 UTC

(In reply to Polina from comment #5)
Thanks, so that is verified then.

Comment 7 Sandro Bonazzola 2018-03-29 11:10:19 UTC

This bugzilla is included in oVirt 4.2.2 release, published on March 28th 2018.

Since the problem described in this bug report should be
resolved in oVirt 4.2.2 release, it has been closed with a resolution of CURRENT RELEASE.

If the solution does not work for you, please open a new bug report.