[mythtv-users] Missing SBE locks/hangs MBE???

[Michael T. Dean]

On 02/09/2013 04:54 PM, Michael Watson wrote:
> On 10/02/2013 2:42 AM, Michael T. Dean wrote:
>> On 02/08/2013 05:12 PM, Michael Watson wrote:
>>> On 9/02/2013 5:18 AM, Jonathan Larson wrote:
>>>>
>>>> Hello All,
>>>>
>>>> I’ve got 5 SBEs that stay on 24/7 normally. They all connect to a 
>>>> tuner-less (except for a dummy tuner) MBE virtual machine. 
>>>> Yesterday, one of the SBE’s had a hardware failure and stopped 
>>>> responding. Shortly afterwards the MBE stopped responding via its 
>>>> status port or mythweb. And shortly after that the other SBEs also 
>>>> gave up because they couldn’t contact the MBE. Basically, a single 
>>>> hardware issue on 
>>
>>>> 1 SBE brought down the whole system.
>>>>
>>>> The storage for recordings is all on the SBEs—2 disks each, defined 
>>>> in the storage groups setup on the MBE. The SBE’s are also 
>>>> cross-mounted via NFS, and they mount a NFS share on the MBE for 
>>>> access to the post-processing user scripts. All those mounts are 
>>>> controlled via autofs, which uses the following options: 
>>>> -rw,noatime,nodiratime,soft,nfsvers=3
>>>>
>>>> I’d really appreciate any advice on how to troubleshoot this cascade 
>>
>>>> failure. I really want to be able to bring down a SBE without an 
>>>> adverse effects to the rest of the system. I wonder if this could 
>>>> be caused by the cross mounting of the storage directories via NFS, 
>>>> and if so, are there any NFS mount/share options that I could use 
>>>> to make them fail gracefully—maybe a shorter timeout period?
>>>>
>>>> Any help would be appreciated.
>>>>
>>>>
>>> Yep, I had the same problems when I had my storage distributed on 
>>> SBE's (and mounted by NFS). Your only options are to centralize your 
>>> storage on the MBE (or a NAS Device), or not mount them via NFS.
>>
>> FWIW, I'm using the latter option--not using NFS.  I have storage on 
>> the master backend, which is only visible to/usable by the master 
>> backend, and storage on the remote backend, which is only visible 
>> to/usable by the remote backend.  I've never had an issue.
> What happens when the SBE is asleep?  You cant watch a recording that 
> is stored on the SBE (obviously), but Myth does not handle it very 
> well (or doesnt handle it at all), you simply cant watch the recording 
> unless you manually power up the SBE.

Exactly.  I just make sure to wake my entire system before watching 
anything.  It's easy enough to do with a script and wake on LAN.

>   Ideally in this scenario the MBE would wake the SBE, and advise the 
> user of what is happening.

The entire shutdown/wakeup/sleep approach (technically, all 3 of the 
different approaches) need to be reworked throughout MythTV.  That would 
be a reasonable capability to add in that rework.  Cleaning that up is 
on my TODO list--just a long way down there, right now (though it could 
bubble up closer to the top in the next couple of years).

>>
>> I used to use NFS on a system I help a friend maintain, and it did 
>> have lots of problems with NFS when the NFS server disappeared. 
>> Because of that--and my desire for reliability--we reorganized the 
>> system so the NFS wasn't required (and are using MythTV streaming for 
>> recordings and Video Library videos).
>
> You still need to mount Pictures and Music locations if you want to be 
> able to access these from remote FE/SBE (or synchronize this data 
> amongst the relevant machines somehow).

True, though I don't use those (I don't have a collection of music--I 
have a Pandora subscription and don't buy CDs/MP3s/... since I have no 
desire to "own" any music--and have never had a desire to display 
pictures on my TV).  And, since your recording file systems would 
(should) be separate NFS mounts, you can just mount the music/pictures 
and--I'm guessing--NFS failures wouldn't impact MythTV's 
recording/backends (because only the frontends use music/pictures).  I 
may well be wrong in my guess, though, so I'll let others chime in if 
that's not the case.

Mike