[mythtv-users] Problems with multiple pvr cards

[Michael T. Dean]

On 05/09/2007 11:43 AM, Brian Walter wrote:
> Tom Lichti wrote:
>   
>> Brian Walter wrote:
>>> Well, I think I have isolated it to something in the disk subsystem.  I 
>>> upped the default write buffer in libmythtv, and, lo and behold, the 
>>> error now only occurs once every 30 minutes...
>> Is your backend also running mysql? If so, and the errors are occurring 
>> on the half hour, it's likely the scheduling queries that are causing 
>> the error. I have 2 PVR-250's, 1 PVR-150, and an HDHR with one HD and 
>> one QAM/SD tuner setup, and I can record from all 5 at once with only 
>> very occasionally getting a buffer problem (which does not take down the 
>> whole box, btw), but I have the database on another machine, and I am 
>> running a RAID5 disk, so it can be done.
> Yeah, I'm beginning to think RAID might solve a lot of problems.  
> There's nothing else running on the backend except the backend.  Mysql 
> is on another machine, as is all the commflag jobs.

As a point of reference, I'm running MythTV 4-PVR-250 combined 
frontend/backend with the MySQL server (and a bunch more) on a machine 
without RAID and can successfully record from all 4 PVR-250's while 
doing 1 commflag job and playing back a previously-recorded show.

Although I'm not now, I used to run this setup with LVM for the 
recording partition.  IMHO, simple is the best approach.  MD (RAID 
and/or LVM) adds complexity and isn't really necessary for a DVR (at 
least with my interpretation of the value of recorded TV).

I'd say check your UDMA support, make sure you're using the proper 
chipset driver for your motherboard, and don't put the recordings 
directory on the same disk (and, ideally, not on the same bus) as the 
root partition.

Mike