[mythtv-users] Warning before upgrading

Michael T. Dean mtdean at thirdcontact.com
Mon Nov 2 23:25:16 UTC 2009

On 11/02/2009 05:33 PM, Ron Garrison wrote:
> On Mon, Nov 2, 2009 at 1:07 PM, Michael T. Dean <mtdean at thirdcontact.com> wrote:
>>  e) If at all possible, do not change MythTV system host names (to keep the
>> upgrade as simple as possible)
>> If you change hostnames on a MythTV system, it is critical that you update
>> all the data in the database to change the old hostname to the new hostname
>> so recordings, settings, keybindings, jumppoints, and /much/ more are
>> properly found for the host.  Doing so is not straightforward--do /not/ do
>> so manually through SQL.  Instead, use the restore script to change the
>> hostname (
>> http://www.mythtv.org/wiki/Database_Backup_and_Restore#Change_the_hostname_of_a_MythTV_frontend_or_backend
>> ).  However, it is critical that you change the hostname after restoring the
>> database but /before/ running any mythtv applications
>> (mythfrontend/mythbackend/mythtv-setup) on the host with the new hostname.
>>  If you forget to do so, changing the hostname becomes /much/ more
>> difficult--to the point that restoring your pre-upgrade backup and doing the
>> upgrade properly, and using the script to change the hostname, is the
>> easiest solution.
> I inadvertantly did this when I created a new system then imported a
> couple of tables from my old system.  Suprisingly I've noticed no
> negative effects but I will go through and attempt to straighten it
> out anyhow.  Thanks for the heads up.

In some configurations Myth will weather the changes to hostname without 
issue.  Basically though, in more complex configurations--with multiple 
hosts and non-local storage--you can have issues.

If you haven't noticed any issues, your best bet is likely to leave it 
as it.

If you do notice issues, you can use the restore script ( 
) to change the current/"new" hostname to some "garbage" value then 
change the old hostname to the new hostname.

So, say your old hostname was ancient and your new (and desired) 
hostname is cuttingedge, you could use:

mythconverg_restore.pl --change_hostname --old_hostname="cuttingedge" 
--new_hostname="unusedgarbage" &&
mythconverg_restore.pl --change_hostname --old_hostname="ancient" 

That way, everything associated with ancient is now associated with 
cuttingedge, but the new stuff created for cuttingedge before you did 
the name change gets moved out of the way.  The "unusedgarbage" data 
will still be in the database, but it won't take much space at all 
(we're talking a few kilobytes of HDD space).

The big problem, though, is if the host with the changed name is 
actually a backend, it will be recording new shows and storing the 
"current" hostname with that information.  So, if you had shows 
associated with ancient and new ones associated with cuttingedge, you 
won't be able to properly fix the issue with the current script.  But, 
since Storage Groups were designed to be very flexible, they may figure 
everything out for you.  If they seem to be doing so, don't try to 
change the hostname for the old information.


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