[mythtv-users] 'Rollbackable' Ubuntu upgrade to 0.21

[Michael T. Dean]

On 03/19/2008 08:48 PM, Mario Limonciello wrote:
> John Veness wrote:
>   
>> I run packaged versions of MythTV on Ubuntu 7.10. I'm currently on 
>> 0.20.2 from gutsy-updates, and am thinking of upgrading to 0.21 from 
>> gutsy-backports.
>>
>> Being the cautious sort, and because I only have the single production 
>> box, I'd like to be able to roll back the upgrade if it doesn't work 
>> out. I know how to backup and restore the database, but I'm unsure about 
>> the packages.
>>
>> How would I uninstall the new packages from gutsy-backports and 
>> reinstall the old ones from gutsy-updates, either via the command-line 
>> or point-and-click in Synaptic?
> The DB backup is handled automatically by myth.

I'm assuming by this you actually mean that the backup will be created 
automatically by MythTV code.  If, instead, you mean that a backup will 
be created automatically by the Ubuntu installation system, ignore 
everything else I say.

As the guy who wrote the code in Myth that does the database backup, I 
would recommend you don't (yet) rely on it to provide a backup before 
the upgrade.  It's easy enough to do 
http://mythtv.org/docs/mythtv-HOWTO-23.html#ss23.5 before you start the 
upgrade process, and doing so (and verifying that it worked before you 
upgrade) guarantees that you'll have a good backup.  There are many 
situations in which the automatic backup will not occur (all dependent 
on the individual user's system configuration--including MythTV 
settings).  And, it's quite easy for a user to "lose" a backup file that 
he didn't create.

What's in Myth now is basically the beginnings of a complete automated 
database backup facility.  It's currently meant to be a last-ditch 
effort to prevent a user from shooting him/herself in the foot, but user 
vigilance is still recommended.  ;)

If everything works out as I plan, you won't need to worry about making 
a backup before upgrading to MythTV version 0.23 (but you will want to 
do a backup before upgrading to 0.22).  The main reason for the 
distinction is that I intend to have a complete automated backup system 
in 0.22, so you'll have several 0.22 backups available when you upgrade 
to 0.23.

>   If you end up needing to
> restore the packages, you can disable gutsy-backports and then go to synaptic
> and roll back versions.  The db can be restored via phpmyadmin for a GUI or the
> mysql cmd line tool.

And the instructions for using the mysql command-line tool to restore 
the backup are at http://mythtv.org/docs/mythtv-HOWTO-23.html#ss23.5 .  
Main difference is that you may need to gunzip (or gzip -d) the backup 
if it's gzip-compressed.

Good luck,
Mike