Is this a bug in qemu-img?
I do a fresh install of Windows vista on qcow2 which works perfectly. Thereafter I use that image as a backing file to make all kinds of updates to Vista, and all that works perfectly too.
Then I use 'qemu-img commit' to commit all the changes I've made to Vista. The problem is that the updated base image doesn't work quite right if I try to run Vista from it -- there are minor malfunctions which indicate that the commit was incomplete or maybe just wrong.
Does this sound like a bug, or are my expectations wrong?
Thanks.
Quoted 10 lines · walt
I do a fresh install of Windows vista on qcow2 which works perfectly. Thereafter I use that image as a backing file to make all kinds of updates to Vista, and all that works perfectly too.
Then I use 'qemu-img commit' to commit all the changes I've made to Vista. The problem is that the updated base image doesn't work quite right if I try to run Vista from it -- there are minor malfunctions which indicate that the commit was incomplete or maybe just wrong.
What's your sequence of commands? Are you using -snapshot?
Signature · 2 lines
I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.
Quoted 6 lines · Avi Kivity
Quoted 5 lines · walt
I do a fresh install of Windows vista on qcow2 which works perfectly. Thereafter I use that image as a backing file to make all kinds of updates to Vista, and all that works perfectly too.
Quoted 7 lines
Quoted 5 lines
Then I use 'qemu-img commit' to commit all the changes I've made to Vista. The problem is that the updated base image doesn't work quite right if I try to run Vista from it -- there are minor malfunctions which indicate that the commit was incomplete or maybe just wrong.
What's your sequence of commands? Are you using -snapshot?
No, not using -snapshot anywhere. I'm not sure how much detail you want, but here's from the beginning:
#qemu-img create -f qcow2 vista 20G #qemu-system-x86_64 -m 2048 -cdrom vistasp1.iso vista [install vista without updating and exit] #qemu-img create -f qcow2 -b vista vista.delta #qemu-system-x86_64 -m 2048 vista.delta [update vista with all the recent patches and exit]
Everything above works perfectly. I can reboot vista, check for new updates, create user accounts, all the normal stuff. Now comes the trouble:
#qemu-img commit vista.delta [takes >1 hour]
Now, IIUC the base image vista should be entirely useable by itself, i.e. I can delete vista.delta and everyting should still work correctly?
But it doesn't. For example, when I boot vista and try to look for windows updates, the updates page is almost blank and completely non-functional. There may be other problems too, but I haven't bothered to look.
BTW, I've been through the same steps twice and get the same results, so I don't think it's flakey hardware. OTOH today is a new day, so I'll try it again to triple check.
Any thoughts?
Thanks.
Quoted 6 lines · walt
...
BTW, I've been through the same steps twice and get the same results, so I don't think it's flakey hardware. OTOH today is a new day, so I'll try it again to triple check.
Tried again all the way from the beginning and got the same result. The commit step is where things go wrong every time.
I know qcow2 is not considered quite ready for prime time, but having that commit feature is important to me so I'd love to see it work correctly.
Any chance that 'commit' could be added to raw as well as qcow2?
Thanks.
Quoted 2 lines · walt
Any chance that 'commit' could be added to raw as
well as qcow2?
Raw images by their nature can't contain metadata -- they have only the exact contents of the virtual drive, which is what makes them "raw" -- so they by definition can't support copy-on-write (and thus commit) or other functionality requiring metadata.
Quoted 7 lines · walt
Everything above works perfectly. I can reboot vista, check for new updates, create user accounts, all the normal stuff. Now comes the trouble:
#qemu-img commit vista.delta [takes >1 hour]
The facts it takes very long is fixed in QEMU SVN. It will be fixed in KVM as soon as the QEMU SVN is pulleD.
Signature · 4 lines
.''`. Aurelien Jarno | GPG: 1024D/F1BCDB73 : :' : Debian developer | Electrical Engineer `. `' [email protected] | [email protected] `- people.debian.org/~aurel32 | www.aurel32.net