Thanks. Some stuff are clear now. I started a VDI Open Source project (http://www.ucs.br/projeto/osdvt/) and your information will help a lot.
Pahim On Thu, Dec 16, 2010 at 4:16 PM, Stefan Weil <w...@mail.berlios.de> wrote: > Am 16.12.2010 18:45, schrieb Stefan Hajnoczi: >> >> On Thu, Dec 16, 2010 at 4:34 PM, Amador Pahim <ama...@pahim.org> wrote: >>> >>> Thank you for your answer. Just one more question: If, while my >>> "snapshot" vms are running, the main disk is modified by a non >>> "snapshot" vm? For example, installing some extra software.. this can >>> freeze vms or something? >> >> Correct, it is not safe to modify the base image while there is >> another disk image backed off it. >> >> The reason for this is that the image only needs to store the changes >> that were made on top of the base image. For anything which hasn't >> been modified it will go back to the base image and read data from >> there. >> >> If you modify the base image, then the filesystem in the base image is >> not longer what your image file was created from and you have an >> inconsistent view of the disk. It leads to odd behavior and is >> unsafe. >> >> Stefan > > There are useful scenarios where using the same disk > simultaneously from a snapshot vm and a real system > works. > > If you have a hard disk with a dual boot configuration, > it is sometimes useful to boot one configuration with > the real system, then start qemu and boot the second > configuration. > > Even booting the same configuration twice > (once with the real machine, once with qemu snapshot) > is sometimes useful and works to a limited degree. > It is a simple way to try new bootloader configurations > or other boot setups. > > Regards > Stefan > >
