[mythtv-users] Rebuilding a FE/BE system (the stupid way)

[Michael T. Dean]

On 01/16/2013 10:15 AM, Science Technician wrote:
>   I am hoping someone can help with what I am trying to do.
>
>   Firstly a little background.
>
>   I am the science technician (although I used to be an IT Tech)
> in a school and under a previous IT Admin I was asked to set up a MythTV
> Box for the science department with the prospect of rolling out across
> the school.
>
>   I did this using MythDora and the way the system is used is that all users
> interface to the system via MythWeb. Myself excluded as the FE/BE System
> sits under my desk so I can get at the FE directly.
>
>   In the long run we didn't roll out MythTV across the school primarily
> because the IT Admin left last year before we had the chance.
>
>   Our new IT Admin take the view that if they don't understand something and it
> breaks down then they don't try and fix it but replace it with something they
> do understand... or better still something that comes with an external support
> contract so they don't have to understand it.
>
>   This means that now I want to switch from MythDora to MythBuntu (I can explain
> why I want to make the change but don't want to clutter this positing even more)
> the response I am getting is "Well why don't we just get AppleTV or Sky".
>
>   I can do the switch myself but I am unable to release any recourses eg. a spare
> machine or even a spare hard drive as Admin are unwilling to spend any money on it.
>
> Sorry for the rather long intro but it helps explain why I am needing to do what I
> am.
>
>   The MythTV setup works really well for us in science and as long as it doesn't
> need any support from the IT Admin we can keep using it so:
>
>   Is it possible to build a new BE/FE system on the current machine by partitioning
> the current drives and then transfer the recordings across?
>
>   I would be happy to re scan for channels and only move recordings if that is easier.
>
>   The HDs have plenty of space to partition but it is set up using LVM something I am not really familiar with and had I know Fedora was going to use it I would have opted for Ubuntu.
>
>   The set up is one small HD and one 1TB HD. I would like if possible to end up with the new Ubuntu + Myth to end up on the small HD and all Media to be on the 1TB HD.
>
>   I appreciate no sane person would choose to start from this position but my options are limited.
>
>   Also any advice on partitioning software to use would be appreciated.
>
> Thanks in advance and sorry again for the long winded intro.

I'm not exactly sure what you're trying to do, but changing the host 
configuration of your MythTV system is a very easy process--and not one 
that "no sane person would choose to start from."  :)

It sounds like you have one master backend and no remote backends, 
correct?  If so, then this should be an easy MythTV upgrade.  You would 
simply back up the database on your MythDora-based 0.24 system (using 
http://www.mythtv.org/wiki/Database_Backup_and_Restore ), and then make 
sure you've put the database backup and all the recording files 
somewhere safe (i.e. somewhere that won't be formatted/partitioned away 
by your Mythbuntu install--and I'd recommend keeping a couple copies of 
that DB backup, since it's the one you must go back to if you have any 
issues, such as database failures), then install Mythbuntu.  Then, 
restore the database backup on the Mythbuntu box.

I recommend using the same host name for your new system.  If you can't, 
you can use 
http://www.mythtv.org/wiki/Database_Backup_and_Restore#Change_the_hostname_of_a_MythTV_frontend_or_backend 
to change the host name--just make sure you do so before running any 
MythTV applications on the new host.  Note that you run that separately 
from restoring the database backup.  Although the changes are made by 
the restore script, it does not actually restore a database when it's 
making the changes.

At this point, you can run mythtv-setup to upgrade the database to the 
new version, check/update any settings.  You'll probably want to delete 
all of your existing capture cards (with "Delete all capture cards", and 
not "Delete all capture cards on <hostname>") since you're going to a 
new kernel with newer capture card drivers (and you may even be adding 
or removing some of the capture cards you had on the old system). See 
http://www.gossamer-threads.com/lists/mythtv/users/264034#264034 (and 
you only need to do the "Delete all video sources" portion if you're 
changing which channels are available or how you're recording them (i.e. 
tuning information changes, such as by switching from analog to digital 
capture or whatever).  Once done, you can re-create capture cards and 
re-connect inputs.  If you had done the Delete all video sources 
portion, you'll need to re-create capture cards, re-create video 
sources, re-connect inputs, and re-create channels.

You'll also need to update your Storage Group directory lists to point 
to the location(s) you've decided to store your old recordings and write 
new recordings.  Make sure when you put the recordings in place, you 
also verify ownership (should be owned by the user running 
mythbackend--likely mythtv user) and permissions of both the files (at 
least read/write for the user running mythbackend), the directories 
they're in (at least read/write/execute for the user running 
mythbackend), and the directories leading up to them (at least 
read/execute for everyone).

If you had multiple backends and are trying to "merge" them into a 
single master backend system, there's a bit more work to do, but all the 
above applies, still, so feel free to start on that and let me know 
you're merging old hosts into one and I'll give you the additional 
directions.  (It basically being 
http://www.mythtv.org/wiki/Backend_migration#Retiring_an_old_backend .)

So, from a MythTV perspective, this should be a simple and pretty 
painless upgrade.  From a distro perspective--i.e. installing (and 
getting to know) the new distro (and how it does things)--or the 
LVM-configuration/-changes perspective, though, it may not be so 
simple.  I'll leave helping with those things to others who understand 
them better than I.

Mike