[mythtv-users] Mythbacked on ESXi 5.0

[Raymond Wagner]

On 10/24/2011 11:39, Tim Draper wrote:
> since the majority of the time, both my windows and mythtv installs 
> are idle, then why not stick them on the same hardware?

If you use Windows for basic web browsing and email, then why are you 
not just running Linux in the first place?  If you use Windows for 
things like games, or other applications that only work on Windows and 
use a lot of power, then chances are you are going to need access to 
resources that you cannot get through a VM, and your system load would 
be disruptive to MythTV anyway.

The big consequence of migrating multiple primarily idle servers into 
one machine is that their loads tend to be bursty.  If those bursts 
occur at different times, everything is great.  The applications get 
everything they need, and couldn't care that they're sharing the 
hardware.  If those bursts occur simultaneously, resource bottlenecks 
mean they both take more than twice as long.  This is one of the big 
reasons why it is recommended not to run mythbackend on a machine used 
for a desktop, where an active user may cause a lot of IO and CPU load 
browsing the web.  The other is that users tend to do usery things that 
result in loss of system stability.

> 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.

I don't see how this is something exclusive to virtual machines.  MythTV 
doesn't store any configuration information outside the database, so it 
is inherently portable.  Change the IP address registered in the 
database as the master, and now you've just promoted one of your slave 
backends.  Run the utility in the backup tool to alter hostnames, and 
now you've brought all your configuration information from your previous 
system.  If you want true portability, make an ISO, loop mount it, 
chroot in, and install MythTV and all its dependencies into there.  One 
way or another, it's never going to be painless because you will always 
have to migrate your storage and recording hardware.