[mythtv-users] Slave backend storage

Jim Abernathy jfabernathy at gmail.com
Wed Oct 21 10:33:39 UTC 2020

On 10/21/20 5:32 AM, Mike Perkins wrote:
> I have a scheduling conflict coming up with no obvious way around it.
> My first thought was to dig out one of my old USB Hauppauge tuners and 
> make up a new source that could be used to cover the issue, but then I 
> didn't really want to spend time tampering with the Master backend and 
> possibly upset something, all for a temporary fix.
> So, the next idea was an ad hoc slave backend. I have a spare box I 
> can use - in fact it is an old master backend box - but the question 
> of what to do with the storage comes up.
> I would rather store the video files on the MBE. Since the video 
> directories on the MBE are already shared over NFS, that would seem 
> the simplest solution. The alternative is local storage, but then when 
> I decommission the SBE I'd have to move the vidoes; no biggy but the 
> MBE might get confused when the SBE disappears.
> Are there any rules out there how this would work? Problems? Suggestions?

Having recently done some testing with slave backends, I'd advise 
caution.  I didn't have a real reason to build one, but I wanted to test 
the use of one. In my case I used a RPI4 as a SBE but I still had to 
mess with the Storage Groups on the MBE.  In my case I used the SBE's 
own storage for the experiment.

It all worked, but there must be a specific order to decommission the 
SGE.  I ended up with a MBE only that was always looking for videos that 
had been recorded on the slave backend.  These were test programs that I 
didn't care about, but the master back end was always complaining about 
them not being found. I'm not good enough at hacking mysql to make that 
go away.  Luckily, I did a complete fresh Master backend build when I 
switch to Ubuntu 20.04 and MythTV v31 so the problem went away.  But 
that could be harsh for some.  Anyway what I did is documented at the 
Mythtv Forum:


Knowing what I know, which is very little, I'd just add in the USB tuner 
into the Master backend. I'm always adding and removing tuners on my 
MBE, since my main tuners on the MBE are never touched it has always worked.

One complete independent way of getting this recorded is to use some 
small and disposable like a RPI and USB tuner setup as an independent 
MBE Combo.  Once the recording is over you could move the recording to 
the NAS in the Video Storage group.

Jim A

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