hello, I think it's not qemu relative but windows relative Windows do a lot of things as auto defrag disk ( without monitoring) when idle time read this document: http://www.vmware.com/files/pdf/VMware-View-OptimizationGuideWindows7-EN.pdfand optimize your guest.
Regards, Nicolas P. 2012/5/23 Charles.Tsai-蔡清海-研究發展部 <charles.t...@cloudena.com> > Stefan, > > Here are what we tested and found for this issue. > > 1. We checked the integrity of the qcow2 image by running > “qemu-img check” and it looked good. > 2. We monitored the I/O activities of VM using > “Process monitor”, “Process explorer” and could not find a process > running an aggressive I/O activity in the background. > > In the guest OS, the following configurations are turn off to cut > down I/O activities. > 1. Disable the NIC. > 2. Disable Windows automatic update. > 3. Disable the page file of the virtual memory. > > After the VM ran for overnight, the image size for the running VM > grew up to 3G bytes. > > > This issue is very easy to be duplicated. Here are the steps. > > 1. Create a qcow2 image of 64-bit Windows 7 VM from the CD. > 2. Launch the VM > 3. Turn off the VM configurations stated above. > 4. Let the VM run. > 5. Watch the growth of the VM image size. The longer the VM > runs, the bigger the size of the VM is. > > During the run-time, you can run “process monitor” to watch guest > OS’s I/O activities. You can see File I/O, registry I/O from the > system during the run-time in this test case. But the growth rate of the > image size seems to be greater than default system I/O. > > > -----Original Message----- > From: Stefan Hajnoczi [mailto:stefa...@gmail.com] > Sent: Monday, May 21, 2012 9:24 PM > To: Charles.Tsai-蔡清海-研究發展部 > Cc: qemu-devel@nongnu.org; Jonah.Wu-吳君勉-研究發展部 > Subject: Re: [Qemu-devel] The image size of instance VM keeps growing > > On Mon, May 21, 2012 at 10:08 AM, Charles.Tsai-蔡清海-研究發展部 > <charles.t...@cloudena.com> wrote: > > We can run a tool to see if there is any active I/O or not. Does the > image size shrink back if an I/O activity stops? > > What we found here is that the image size kept growing. If this problem > persists, it could eat up the entire disk space. > > It's possible for an image to grow larger than its backing file due to the > layout and metadata of qcow2 (or any image file format). But this overhead > should be fixed to maximum 1 MB, maybe (assuming you are not using qcow2 > snapshots where the file can grow arbitrarily). > > If the image file is growing endlessly then there is a problem :). > The starting point is figuring out which I/O request causes this to happen > so it can be reproduced and debugged. Can you isolate the problem to a few > steps that can be reproduced? > > Stefan >
