[mythtv-users] Storage Group Priorities

[Chris Pinkham]

* On Sat Apr 26, 2008 at 03:30:43PM -0700, Drew Tomlinson wrote:
> Thanks for your reply but I remain a bit confused.  If I understand what 
> you're saying and I wanted the default values, I would just add the 
> following rows to the Settings table:
> 
>            VALUE                     DATA          HOSTNAME
>     SGweightPerRecording             10
>     SGweightPerPlayback               5
>     SGweightPerCommFlag               5

No, you shouldn't need to touch those.

What you want is some rows that look like this:

mysql> select * from settings where value like "%weightper%";
+-----------------------------------------------------+------+----------+
| value                                               | data | hostname |
+-----------------------------------------------------+------+----------+
| SGweightPerDir:yakko:/nas/video5/mythtv/recordings  | 30   | NULL     | 
| SGweightPerDir:alive:/nas/video1/mythtv/recordings  | 10   | NULL     | 
| SGweightPerDir:yakko:/nas/video4/mythtv/recordings  | 30   | NULL     | 
| SGweightPerDir:alive:/nas/video4/mythtv/recordings  | 30   | NULL     | 
| SGweightPerDir:mythtv:/nas/video3/mythtv/recordings | 20   | NULL     | 
| SGweightPerDir:mythtv:/nas/video2/mythtv/recordings | 20   | NULL     | 
| SGweightPerDir:mythtv:/nas/video5/mythtv/recordings | 30   | NULL     | 
+-----------------------------------------------------+------+----------+
7 rows in set (0.00 sec)

These basically set starting weight offsets for the particular host and
directory specified.

A recording has a default weight of 10 as you show above.  So in a
scenario where you have 1 host with 3 drives and you only want to use
the one external drive as a last resort, you could do something like
this:

+-----------------------------------------------------+------+----------+
| value                                               | data | hostname |
+-----------------------------------------------------+------+----------+
| SGweightPerDir:host1:/nas/video3/mythtv/recordings  | 20   | NULL     | 
+-----------------------------------------------------+------+----------+

That would give the 3rd drive a starting weight of 20 which means that
Myth acts as if it already has the equivalent of 2 recordings already
going to it.  That would cause the storage scheduler to prefer the other
two drives for the first 4 active recordings and then the 5th would be
scheduled based on which drive had the most free space.  If you wanted
the fifth active recording to go to this drive then set the value to 19
instead.  Playback, transcoding, and commercial flagging also have
weights assigned that are counted towards the total, so if you have
those running during recording it can also affect where active
recordings are stored.  If you only want this large external storage to
be used as a last resort, I'd keep it's starting weight set at 20 or
above.  I use 30 on some of my weights as you see above.

Because the Storage Group code will find the file when it needs it, you
can move these files from the local fast storage to the slower external
storage without having to update the database at all as long as your
Storage Group is configured to see all the right directories.  You
could even setup a user Job to move the recordings around automatically
for you if you wanted.  Eventually there will be a builtin job for this,
but I haven't fully tested my patch to do that and haven't written any GUI
glue for it either.  It's been put on the back burner behind other
things right now.

--
Chris