Seeking advice on virtualization

[Paul Webster]

even cooler you get 'clones' so you can say make a raw/zvol of debian or
whatever you like then if you make a snapshot of it and clone it to
something else 'debian2' it uses no space until you write/delete/edit
something, basically the clone only has diffs.

And yes zvols are literally like raw devices, dd style you can infact take
a raw image and dd it to a zvol

On 7 August 2018 at 19:57, Jakub Chromy <hicks at cgi.cz> wrote:

> 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
>
>
> CGI Systems div.
> ----------------
> CGI CZ s.r.o.
> sales at cgi.cz
> 775 144 257
> 234 697 102
> www.cgi.cz
>
>
> 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).
>>
>>
> _______________________________________________
> freebsd-virtualization at freebsd.org mailing list
> https://lists.freebsd.org/mailman/listinfo/freebsd-virtualization
> To unsubscribe, send any mail to "freebsd-virtualization-unsubs
> cribe at freebsd.org"
>