At 2013-12-13 06:25:44,"Eric Blake" <eblake@redhat.com> wrote: >On 12/09/2013 09:03 PM, lyz_pro@163.com wrote: >> Hi all >> >> I have a problem when I use `virsh attach` to attach a qcow2 disk to vm without argument --subdirver=qcow2 >> and this makes the qcow2 disk become a raw format disk, and the data in this disk is missing in guest os >> and also I have used guestmout to confirm this, the same result. > >The format of a file is important. By default, libvirt refuses to probe >a file for its format, because any raw file can contain contents that >look like any other format, making libvirt and/or qemu misbehave if the >guest abused the raw contents to intentionally resemble a different >format (this is a known CVE in the past). You can flip an option in >/etc/libvirt/qemu.conf to request libvirt to probe image formats, at >which point you can then omit the format but the guest will still get >the data from the qcow2 format instead of abusing the file as raw; but >this is a security risk if you do not trust any guest that has ever run >on the image file. > >> >> Is there any way to let me find back the data in this disk ? > >If the guest wrote to the disk, then I hope you had a good backup. If >the guest merely read from the disk but didn't write any data, then >unplugging the disk and replugging with the correct qcow2 format will >fix things. > >-- >Eric Blake eblake redhat com +1-919-301-3266 >Libvirt virtualization library http://libvirt.org >