Re: Rant: The need for books to document things (was: Re: Virtual Machines)
On Mon, Aug 22, 2022 at 01:58:57PM -0400, rhkramer@gmail.com wrote:
> On Monday, August 22, 2022 08:50:02 AM Tom Browder wrote:
> > Can anyone recommend a good book on the general topic of VMs? Or one on a
> > specific VM stack (using Linux as base)?
>
> At this point, I've requested two books on the subject (by inter-library loan)
> -- one about 700 pages, the other about 280 (iirc) pages.
>
> It just seems documentation ought to be better / simpler / easier to use than
> that.
>
You could do worse than the original O'Reilly book on SSH.
> Aside: I'm hoping to do my part -- when I get an understanding of the parts of
> ssh I want to understand to my level of satisfaction, I intend to document it
> (on my WikiLearn wiki). I might even document it before then with notes about
> things I'm uncertain about or may have just plain omitted (for lack of
> information). (I say that because I've spent too much time on this, and we'll
> soon have to concentrate on more urgent priorities.)
>
> Aside: I do recognize that when I started digging into ssh, and those methods
> of authentication, I just didn't realize how complicated it is at some levels,
> with all the different encryption, hash, cipher or other related methods that
> can be used, and things like Diffie-Hellman key exchange, but still,..
>
> And there are other people trying to help by writing accurate yet simplified
> stuff on things like wikis.
>
> Hmm, but I wonder, can I start to write something on VMs that might be helpful
> to the OP or to some other newbie to VMs?
>
> I might try, even though I have never used a VM (well, I might have once, but,
> at the moment, any recollection of that seems to be completely faded.
>
> So here's what I might try to tell someone.
>
> I'd say that a VM (virtual machine) can be used as at least one of its
> purposes, to run some different software (maybe usually the OS, or including an
> OS) in a computer.
>
> For example, as was mentioned / recommended in some other recent thread, to a
> person who wanted to run and old version of openssh (the version that ran on
> Debian 9) on a computer with Debian 1 as an OS, is to create a VM and run
> Debian 9 and its version of openssh in that VM.
>
> That can be done. There are issues to consider, like which and how the
> hardware (and software) resources of the "parent" OS can be addressed by the
> software in the VM.
>
> There are various programs / systems that can be used to set up a VM, and, I'm
> pretty sure there are options in at least some of those systems to address the
> questions of which and how the resources of the parent OS can be addressed by
> the software in the VM.
>
> One example might be the question of can you cut and paste between the VM and
> the parent (or, if there is more than one VM, can you cut and paste between
> VMs).
>
> Others to consider (maybe):
>
> * can the software in the VM (directly) address filesystems in the parent,
> or must either new filesystems be created in the VM or access explicitly
> allowed for some filesystems
>
> * can the network be addressed from the VM
>
> * can you print from the VM
>
> Like I'm trying to imply, the answers to those questions may (probably does
> vary) by the software used to create the VM and options that may or may not be
> set.
>
> I wonder if that is a helpful start, or what the next questions might be....
>
> Oh, maybe a few more things:
>
> * terminology: I think VMs are sometimes referred to as containers. Also,
> I think there are other things that are referred to as containers that are not
> VMs
>
A container need not be a full VM: in most cases a VM is more than a container.
> * I have the idea that at least to some extent that the concept of VMs
> somewhat evolved from the concept of chroot jails (so maybe a chroot jail can
> be considered a sort of primitive version of a VM?)
>
> * I would list the names of a few software systems that can create a VM --
> not many of them come to my mind at the moment -- maybe qemu is one of them??
> (I should google that, but I think I'm quitting for now.)
>
> Oh, ok, one "hit" from google [vm software for linux] -- oh, wait, what I
> quoted is "opensource virtualization software" -- should I distinguish that
> from VM (virtual machine) software, and, if so what is / are the
> distinction(s)? (By the way, qemu is mentioned in some other hits.)
>
> <quote>
> Which VM software is best for Linux?
> Top opensource virtualization software for Linux
> 1
> Oracle VirtualBox. VirtualBox. VirtualBox was founded in 2007 by Oracle
> Corporation. ...
Partially Free software, some parts have a personal use licence. Potentially
avoid.
> 2
> Linux KVM. KVM. ...
Pretty much the standard.
> 3
> Microsoft Hyper-V. Hyper-V-Manager. ...
This is useful if the underlying machine is running Windows. WSL2 can
also run on top of Windows and is a smaller shim than Hyper-V
> 4
> Xen Project. Xenproject. ...
Read up on paravirtualisation
> 5
> oVirt. ovirt. ...
Possibly now dead - from Red Hat - may be the basis for RHV below.
> 6
> Red Hat Virtualization (RHV) Red Hat Virtualization. ...
> 7
> GNOME Boxes. GNOME Boxes. ...
Native virtualisation inside modern GMOME
> 8
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