Video files and Master Backend Override

[johan@…]

Situation:

1. A NAS with video files accessible through NFS.

2. A Master Backend with NFS mount to videos on NAS, directory specified with Storage Groups.

3. A Slave Backend with NFS mount at the same location to videos on NAS. Storage group NOT overridden. (Inherited.)

4. An independent Frontend.

5. The slave backend is automatically shutdown, and therefor is not always available, the option "Master Backend Override" is enabled.

This should make sure all media is streamed from the Master Backend.

Observed issue:

When the slave backend is available, doing a "Scan for Changes" on the frontend of the video files "sees" the video files available on the slave backend. When the slave backend is NOT available, doing a "Scan for Changes" on the frontend of the video files "sees" the video files available on the master backend. This affects the way the video location is stored in the database.

The files will always play, irrespective of the status of the slave backend. (It automatically finds the correct location.) But, when the files are initially learned to be on the slave backend, and the slave backend is available, they will also be streamed from the slave and not from the master. (Verified by viewing "playback data".) When this is the case, the slave backend is still seen as "idle" and might shutdown, causing the stream to stop working.

Is this normal behavior?

I see several issues:

1: When Streaming video files from Slave backend, this backend is still considered "idle" and might shutdown, interrupting the stream.

2: The "Master Backend Override" seems to suggest the files will always be streamed from the Master Backend, even if they are also available on the Slave. This doesn't seem to be the case in this situation.

3: Perhaps the videofile location stored in the DB should favor the Master Backend when the same file is also available on slave backends? Especially when using "Master Backend Override".

I'm currently using 0.26-fixes, but I do not think thi is a new bug that was introduced in this version.

[Raymond Wagner]

Videos are only stored against a single system, defined by the host field in the videometadata table. The frontend will only ever try to stream the file through that system. As a side effect of the moved-file detection of the video scanner, when a file shows up in multiple locations simultaneously, such as on two separate hosts, it will alternate between locations on each scan.

Your two options are to either not mount those videos on your slave backend, or to give your slave backend a dummy path in the Videos storage group, so it does not fall through to scanning the master's paths.

[sphery]

And the "Master backend override" setting applies only to TV recordings. Note, also, that file handling will be changing in some future version of MythTV such that things will just work and users won't need to worry about configuring MythTV for their system/storage configuration. Until then, you'll have to use one of the approaches mentioned by Raymond.

[johan@…]

Thanks you for the detailed explanation.

With that in mind I will reconfigure and troubleshoot further to find out about the "idle" backend and shutdown. If valid, I will file a new bug for this.