Seeking advice on virtualization

[Jakub Chromy]

> I was writing about "hard disk file" format, in which a hypervisor
> (i.e. bhyve, kvm, virtualbox) is keeping a disk for emulated
> machine. Wikipedia calls it "img format":
>
> https://en.wikipedia.org/wiki/IMG_(file_format)
>
> Advantage from using this format (as opposed to something like qcow or
> vmhd) is that, in theory (and even in practice) one can boot such
> machine (I mean, virtual machine defined with such "raw" hard drives)
> using any hypervisor.

ZFS ZVOL is a true "raw device" as well... (or at least it did behave 
like that for me):

   dd if=/dev/zvol/pool/mypornhubpremiumarchive0 
of=/var/vm/mypornhubpremiumarchive0.raw

but you get snapshots, zfs send | zfs recv and stuff.

-- 


    regards / s pozdravem


Jakub Chromy


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On 7.8.2018 19:06, Tomasz Rola wrote:
> On Mon, Aug 06, 2018 at 12:07:13AM +0100, Paul Webster wrote:
>> In theory as ZFS works on both linux and BSD you could simply use vdevs and
>> snapshots for easy transport
> Um-hm.
>
> I was writing about "hard disk file" format, in which a hypervisor
> (i.e. bhyve, kvm, virtualbox) is keeping a disk for emulated
> machine. Wikipedia calls it "img format":
>
> https://en.wikipedia.org/wiki/IMG_(file_format)
>
> Advantage from using this format (as opposed to something like qcow or
> vmhd) is that, in theory (and even in practice) one can boot such
> machine (I mean, virtual machine defined with such "raw" hard drives)
> using any hypervisor. Or to put it differently, it is not proprietary
> and is the easiest one to implement, so it is what most probably will
> keep being used years or decades from now (in whatever hypervisor / PC
> emulator of the future day is fashionable).
>
> I believe in the past I have installed an OS (say, FreeDOS) using
> virtualbox and after deciding I would not use virtualbox in a future,
> I started to boot said machine using kvm. Likewise, I believe some
> OSes rejected being installed under certain hypervisor, so one had to
> install them using this other hypervisor and then could happily
> continue to run it under his preferred hypervisor.
>
> All of this made possible thanks to avoiding file formats supported by
> one or only few hypervisors.
>
> Of course there are many hd-file formats and some are supported by
> more than one hypervisor, but the easiest one is raw and in case of
> emergency it can be also mounted as any other block device (always, I
> guess, but I would pay attention to block size mismatch).
>