Bug 518169 - Bad qcow2 performance with cache=off
Summary: Bad qcow2 performance with cache=off
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kvm
Version: 5.5
Hardware: All
OS: Linux
urgent
urgent
Target Milestone: rc
: ---
Assignee: Kevin Wolf
QA Contact: Lawrence Lim
URL:
Whiteboard:
Depends On:
Blocks: 520693
TreeView+ depends on / blocked
 
Reported: 2009-08-19 09:40 UTC by Kevin Wolf
Modified: 2014-03-26 01:00 UTC (History)
7 users (show)

Fixed In Version: kvm-83-113.el5
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2010-03-30 07:52:21 UTC
Target Upstream Version:
Embargoed:


Attachments (Terms of Use)
windowr2 iometer result. (433.11 KB, application/vnd.oasis.opendocument.spreadsheet)
2010-03-01 01:43 UTC, lihuang
no flags Details


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2010:0271 0 normal SHIPPED_LIVE Important: kvm security, bug fix and enhancement update 2010-03-29 13:19:48 UTC

Description Kevin Wolf 2009-08-19 09:40:12 UTC
We had to change the default options for qcow2 to cache=off to avoid data corruption on host crashes. After this change, there have been reports that installations took 2 hours which previously had taken 15 minutes. Upstream qemu has performance fixes that should help here. They need to be backported to RHEL.

Comment 1 Kevin Wolf 2009-08-19 10:02:10 UTC
Posted the backports on virtualist.

Comment 5 Lawrence Lim 2009-08-25 15:24:58 UTC
Hi Kevin,
Could you please provide us with a scratch build which we could test and compare against the current implementation?

Thanks,
Lawrence

Comment 8 Kevin Wolf 2009-08-28 11:37:04 UTC
Hi Lawrence,

I have just created https://brewweb.devel.redhat.com/taskinfo?taskID=1948061. I'm doing this for the first time, so while I hope this is what you need, I'm not 100% sure about it. If it isn't quite right just let me know and I'll make another attempt at it.

Comment 14 lihuang 2010-03-01 01:43:38 UTC
Created attachment 396927 [details]
windowr2 iometer result.

Comment 17 errata-xmlrpc 2010-03-30 07:52:21 UTC
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2010-0271.html


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