[mythtv-users] Mythbacked on ESXi 5.0

[Tim Draper]

On 24 October 2011 16:27, Raymond Wagner <raymond at wagnerrp.com> wrote:

> On 10/24/2011 04:29, Tom Hill wrote:
> > On Sun, 2011-10-23 at 20:55 -0700, Govindarajan wrote:
> >> I am trying to comprehend the advantages of such a set up but I am not
> >> getting convinced. One could just run Mythtv (front and backend) on a
> >> physical box. Running more than just backend VMs or multiple backends
> >> on the same physical box could be one. Could you explain the other
> >> advantages please?
> >>
> > People running separate file storage, router/firewall applications can
> > have them all on the same hardware.
> >
> > m0n0wall, Vyatta, pfSense, FreeNAS, openfiler, etc. will all run very
> > happily in a virtualised environment.
>
> But the question is _why_ would you want to?  One has to seriously
> question the sanity of the person who uses virtual machines so they can
> run half a dozen border firewalls on the same machine.
>
> You completely misunderstand the entire purpose for virtual machines to
> exist.  Modern operating systems have this wondrous technique called
> preemptive multitasking, that allows them to run multiple applications
> on the same image just fine.  You don't need to employ a virtual machine
> to achieve that.  You don't even need a virtual machine to provide
> isolation between applications for convenience and manageability.  A
> simple chroot provides most of the benefits as a VM in that regards, and
> para-virtualization techniques such as jails, containers, and vservers
> can pick up much of the rest, like isolated memory space, dedicated
> network stack, and cpu/memory quotas.
>
> There are really four specific cases to run a virtual machines:
>
> You use a virtual machine because you need to run multiple independent
> kernels.  Para-virtualization doesn't require the same environment, but
> it does require everything be run on the same kernel.  If you've got
> some applications that need Linux, other that need Windows, and still
> others that only run some ancient blend of HPUX or some such, full
> virtualization is your only option.  Well, that or just running multiple
> servers.
>
> You use a virtual machine because you're using software with a licensing
> scheme written by a panel of proctologists.  I'm looking at you,
> TACOMA.  The software grabs all sorts of identifying information about
> the hardware, and the license key is subsequently written to only
> operate off that single machine.  The virtual machine looks like the
> same hardware regardless of where it's running.  Rather than having to
> deal with technical support any time you need to change hardware, you
> throw it on a virtual machine and ignore it.
>
> You use a virtual machine for development work.  Either you need to run
> a completely different architecture, or maybe you just simply want to
> isolate development work from your workstation so its not disruptive
> against other applications you've got open.
>
> Finally the big one, you are running a number of "mission critical"
> server applications for a business, and they absolutely, positively,
> must not go down.  You could perform an analysis on the various
> softwares, and make sure they aren't running any calls that could
> potentially take out the shared kernel and other servers on a
> para-virtualization system.  You could rewrite your application with a
> synchronization mechanism to allow another instance on another machine
> to take up where it left off.  You could rewrite your application with a
> clustered, redundant approach, where loss of any one machine does not
> significantly affect the whole.  All of these cost time and money.
> Virtualization is not a "good" approach, but the industry has determined
> that it is the "good enough" approach.  It is the ugly, brute force
> sledge hammer, but the alternative is a ton of man-hours writing the
> elegant application.  At the end of the day, the quick and ugly approach
> has a lower total cost, and is the better solution for business.
>
> So where does this get you with MythTV?  The home user isn't doing
> anything that is going to be bothered too much by the occasional crash.
> The home user isn't going to have hot spare systems to fail over to in
> the event of a hardware failure (and the free ESXi doesn't allow such
> anyway).  With all its runtime information stored in the database,
> MythTV is already fairly close to the "elegant solution".  Change the IP
> address of the master backend, and with a few keystrokes, a slave
> backend gets promoted to master and you can start back up.
>
> There is a time and place to run VM software, but like Govindarajan, I
> don't see a home user running MythTV to be one of them.  If you find it
> fun and amusing, or even just good practice for a career, have at it.  I
> just don't see how it can make management and operation an easier task.
>
>
>
maybe i've missed the point here - what about multi OS on one machine? for
me, mythtv would be on linux, and i want to use windows for other purposes.
snapshots are also wonderful for those who are not skilled in linux and will
likely break something. (ok, you've mentioned about FS's with built-in
snapshots..)
since the majority of the time, both my windows and mythtv installs are
idle, then why not stick them on the same hardware?
im the opposite of you - i dont see a reason why you WOULDN'T choose VM.

also, and possibly the one everyone would find the most useful; migration.
you can stick it on any hardware and the guest will be the same as it was,
without fear of having to recover or ammend the existing install.
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