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

Kenni Lund kenni at kelu.dk
Sat May 8 08:36:15 UTC 2010

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. Eg. if you use the same operating system
for your virtual machines, you can reduce memory usage quite a lot, as
the memory pages are identical on the different virtual machines.

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.

By running the backend virtually, you can easily switch between
"production" -fixes backend and a "testing" trunk backend. Combined
with PXE-booting for the frontends, you'll be able to switch your full
production system with backend and frontends into a testing system in
no time, with no impact on your production system.

If you're unsure about upgrading your production system, you can take
a backup of the virtual machine image in a few minutes (my production
MythBuntu backend is ~5GB) - or if you run LVM below the host
filesystem, just take a snapshot of the whole disk with all your
virtual images. If something fails during the upgrade, you can have
your old system running within a few minutes.

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

Best Regards

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