[mythtv-users] Wintv-PVR-USB2 and Virtual box. Am I going to far?

Raymond Wagner raymond at wagnerrp.com
Sat May 8 09:12:39 UTC 2010

On 5/8/2010 04:36, Kenni Lund wrote:
> 2010/5/7 Raymond Wagner<raymond at wagnerrp.com>:
>> Virtualization will only serve to increase memory usage, as you lose the
>> ability to use shared libraries, and you are going to duplicate everything
>> in the disk cache.
> Well, new kernels support KSM (Kernel Samepage Merging), which will
> merge identical memory pages.

I've heard of memory de-duplication before, but I didn't know that it 
had made it into the 2.6.32 kernel.  Either way, you still have to run a 
full system, complete with all those duplicated daemons.

> Running the backend in a virtual machine gives you lots of other
> advantages. Often you want to run a completely stable -fixes system
> for the family, but once in a while you run into a problem, and you're
> asked to test if some patch or configuration change solves the issue.
> Or perhaps you just want to test some new feature in MythTV.

This has nothing to do with virtualization.  You can achieve the same 
effect with isolated containers, simple chroot, or even by just by using 
separate prefixes and manipulating the PATH and LD_LIBRARY_PATH variables.

> You also have the advantage of perfect isolation between the MythTV
> backend (+ other services) with the virtual host - eg. you can run
> some enterprise grade Linux distribution with ancient libraries on the
> metal, which only purpose is to do virtualization and nothing else.
> For the MythTV backend and your other servers, you can run whatever
> (bleeding edge?) distribution you prefer, without affecting your host
> environment.

This is the only advantage of true virtualization, the ability to run 
multiple, fully independent operating systems. Virtualization is not the 
end all solution to all problems.  It's the computer equivalent of 
fixing things by hitting them with a sledge.  It's overkill where a much 
simpler approach will achieve the same results.

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