[mythtv-users] Virtualisation .. can it do this? (HP ProLiant MicroServer N40L)

Damian myth at surr.co.uk
Tue Sep 25 20:25:07 UTC 2012

On 25/09/2012 17:09, Simon Hobson wrote:
> Damian wrote:
>> I have noticed, from forums etc, that almost everyone who owns one of 
>> these things uses some sort of technology to run different virtual 
>> OS's on it. I couldn't really see the point of this unless you are 
>> either a developer or an uber-geek (a term I use with the greatest 
>> respect .. I am a merely a semi-geek). It just sounds to me like 
>> there's more that can go wrong than if I was just running the machine 
>> with a standard OS. And I had heard that USB tuners could be a 
>> headache to get working in a virtual machine.
>> I hate things that don't just work these days and can't bare the 
>> headache when things go wrong (I must be getting old!)
>> However, I did have a thought this morning.
>> One thing that constantly trips my up with Mythbuntu is 
>> upgrading/updating it. I know a lot of you would say, if it's not 
>> broke, don't fix it. But I like to have the latest stable version of 
>> MythTV.
>> So, my question is, could virtualisation help with this?
> Yes, but I think it's probably overkill for what you want.
> I bought one of the earlier N36L Microservers, with the intention of 
> running MythTV and my other services on it. However I found that my 
> tuners (PCIe, HVR-1300) didn't work with Xen loaded and more than 4G 
> of physical RAM in the machine. Didn't work as in, in Dom0 they were 
> recognised but any attempt to tune anything returned no data.
> Since they were still on cashback I bought another for everything else 
> and kept one just for Myth.
> What I'd suggest is rather than going for virtualisation, use LVM for 
> everything but a /boot filesystem*. Then it's fairly simple to just 
> create additional LVs, clone your current system over to them 
> (remembering to tweak things like /etc/fstab), and then reboot into 
> the newly made copy. Your original remains safe and sound while you 
> experiment - and when you are ready you can just make the new version 
> your live system by setting the default boot entry in grub.
> * If you do keep a physical partition for /, then you may want to keep 
> another spare one for your tests.
> Obviously you need to keep enough spare room in your LVM VG for any 
> extra volumes you might need.
> This does have the downside that you have to shut down your live 
> system while working on the new one - but as long as you keep an eye 
> on the schedules/upcoming recordings then it should be too hard to 
> find reasonable windows to work in. On the other hand, since you'll 
> probably need your hardware (tuners etc) for some of the testing/setup 
> then you'd still need to shutdown your live system even if you were 
> running full virtualisation.
Thanks for the feedback everyone!

I'm thinking that I'm probably best just setting up Ubuntu/Mythbuntu as 
the OS, and then when I want to 'upgrade', I could just backup the 
system drive before breaking everything so that I can recover from it 
when all goes bad and try again. I have made an image of a drive before 
using some sort of live CD. It was fairly straight forward. Actually, it 
was probably 'PartImage' that I used, as mentioned earlier.

The idea of having several different 'boot partitions' was nice too.

Thanks again everyone. I agree that setting up a virtualisation system 
is overkill for my needs when the other suggestions will give me the 
same 'safety net' without virtualisation.

Cheers all!

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