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Bug 584751 - Win7 guests: cannot enable disk caching on IDE disks
Win7 guests: cannot enable disk caching on IDE disks
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kvm (Show other bugs)
All Windows
low Severity medium
: rc
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Assigned To: chellwig@redhat.com
Virtualization Bugs
Depends On:
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Reported: 2010-04-22 06:49 EDT by Yaniv Kaul
Modified: 2013-07-03 21:50 EDT (History)
4 users (show)

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Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2010-05-07 06:41:09 EDT
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RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description Yaniv Kaul 2010-04-22 06:49:10 EDT
Description of problem:
Although the option exist (Device Manager -> Disk Drives -> 'QEMU HARDDISJ ATA' -> right click -> Properties -> Policies) to enable write caching, once you check it you get an error that it cannot be set.

On XP/32, you can set this.

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

How reproducible:
Always - both on Win7/32 and Win7/64.

Steps to Reproduce:
Actual results:

Expected results:

Additional info:
Comment 1 chellwig@redhat.com 2010-04-28 11:40:24 EDT
Note that you never could enabled/disable the write cache under qemu.  While return success for the SETFEATURES calls, we never take any action.  I suspect the difference is that Win7 issues an IDENTIFY call later to check if we actually advertize a cache now.

Note that in recent qemu we will always advertize a write cache,
Comment 2 chellwig@redhat.com 2010-05-07 06:41:09 EDT
Yaniv, is this serious in any way?  Even implementing changing the caching settings is not a high priority, and backporting to RHEL5 certainly isn't.  I'm tempted to close this as WONTFIX.
Comment 3 Yaniv Kaul 2010-05-07 14:51:41 EDT
I don't think it's serious, except for the user experience, where it appears he can do something, then gets a bit of an ugly error. If you don't want to fix it, close as WONTFIX. I guess there are more important bugs to fix.

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