Round-up of research on virtualization-aware disk image formats

IBM Mirage. Replaces standard formats with their own image format (“MIF”), which is a tar-like format. Advantages are you can easily see into and modify the disk image. Also supports sharing common data between VMs. Disadvantage is that it’s entirely unlike the disk image formats that are already out there, so it seems unlikely to gain traction. Also claim to be doing package upgrades on offline guests which is something libguestfs users have been doing for well over a year.

The paper above mentions the following related work:

Ventana (Stanford). Paper is undated, but latest reference is to 2006. A virtualization-aware filesystem (not block device) which offers lightweight snapshots and branches. Concept seems to be similar to wandering-tree filesystems (most notable modern example being btrfs, but these have been around for a long time).

Machine Bank (Microsoft). Microsoft’s VHD (virtual disk format) with support for sending these around a network, partial caching and so on.

Moka5 engine. Some sort of VDI thing. No information on the website.

VMWare Lab Manager.



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2 responses to “Round-up of research on virtualization-aware disk image formats

  1. Peng Ning

    Hi Richard,

    The package updates on offline VM images in Nuwa is different from libguestfs, assuming you are talking about Tip: Install RPMs in a guest. Nuwa rewrites the installation scripts so that the patch can be installed directly on offline VM images that are mounted in the file system of a patching host. Offline images are updated without the next reboot. In contrast, libguestfs and Shavlik configures a patching task at the first boot of an offline VM.



  2. Peng Ning

    Forgot to mention that the benefit of Nuwa is to save the potentially long delay when booting the updated VM, particularly when the VM hasn’t been used for a long period of time.

    The paper reports experimental results that compare Nuwa with the first-boot method. Nuwa determines if it can successfully perform offline patching through static analysis, and when it can succeed, it reduces the time required by patching up to 40 times when used with Mirage in the experiments.


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