with poor signal on HDHR, mythbackend constantly writing to log

[George Kovatchev]

I have installed the oct 29th mythbuntu 9.10. This is fresh install and I'm using it with HDHomeRun. I get things logged over and over every second and at times more often. For less than one hour the log file reached over 30,000 lines and is nearly 2MB, but the most disturbing is the constant hard disk grinding. The log entries look mainly like these two:

----------------------------- 1 -------------------------------------------------
2009-10-31 23:52:54.559 HDHRSH(10172A63-0): RunTS(): data_length = 48692 remainder = 188
2009-10-31 23:52:54.594 HDHRSH(10172A63-0): RunTS(): data_length = 57904 remainder = 188
2009-10-31 23:52:54.628 HDHRSH(10172A63-0): RunTS(): data_length = 53956 remainder = 188
2009-10-31 23:52:55.264 HDHRSH(10172A63-0): RunTS(): data_length = 3948 remainder = 188
----------------------------- 1 -------------------------------------------------

----------------------------- 2 -------------------------------------------------
2009-11-01 00:50:54.715 Could not find channel 7_1 in TVCT
2009-11-01 00:50:54.758
VCT Terra: channels(1) tsid(0x859) seclength(95)
Channel #0 name(WNLO-HD) 23-1 mod(ATSC 8-VSB) cTSID(0x859)
 pnum(3) ETM_loc(1) access_ctrl(0) hidden(0) hide_guide(0) service_type(ATSC TV) source_id(4)
 descriptors length(50) count(2)
  ExtendedChannelNameDescriptor: 'WNLO Digital Television'
  Service Location Descriptor (0xa1) length(15)
----------------------------- 2 -------------------------------------------------

I also wanted to set the log file to /dev/null, but the log file no longer appears in
/etc/init.d/mythtv-backend
Where is the log file configured from on 9.10?

Thanks,
George

[George Kovatchev (kovatchev)]

OK, I answered my last question. mythtv-backend has been converted to a service and the log file is set up as an argument in

/etc/default/mythtv-backend

I just changed the $ARGS line:

#ARGS="--logfile /var/log/mythtv/mythbackend.log"
ARGS="--logfile /dev/null"

Saves my HDD for sure

[Chris Pimlott (launchpad-chris)]

Actually that log message indicates that you're getting errors in the HD signals. You can confirm this by monitoring hdhomerun's debug info:

watch -n 1 hdhomerun_config ffffffff get /tuner0/debug

You may need to adjust your antenna for better signal. Turning off logging only addresses the symptom, not the cause.

http://www.gossamer-threads.com/lists/mythtv/users/404273

[MarcRandolph (mrand)]

Chris Pimlott: Thank you for pointing that out.
George Kovatchev: please report back if this resolves your issue.

Thanks.

[George Kovatchev (kovatchev)]

Hi and thanks for your replies. I am not sure how this could solve my problem. I know that I have marginal signal on some channels and some days are better than others. This constant HDD activity happens when myth is sitting idle.

I think I will have to keep it with the logging disabled and only turn it on when having problems.

It would be nice to be able to do one or more of these (or perhaps it is already possible):
- aggregate some types of errors and have a delayed write in bigger blocks
- have settings specifying what to log or be able to ignore certain errors
- have limits to how many times to log specific error, e.g. write "Could not find channel" 100 times and then stop until the next restart

Thank you once again.

[MarcRandolph (mrand)]

George: I agree that the multiple log entries per second is excessive - I will forward that bug upstream and see if there is anything they can do about it. In the mean time, I would suggest adjusting your antenna, perhaps even going so far as to try an amplifier for it.

When you run mythbackend -v help, below the list it should say "The default for this program appears to be: '-v important,general'" can you verify that? You might try just -v important.

[Andrew (andrew-rw-robinson)]

I am seeing this as well, but AFAIK, my signal strength is not low. What is odd is that the channels do not seem to match (6_1 vs 9-1 here):

2009-12-19 16:32:31.394 Could not find channel 6_1 in TVCT
2009-12-19 16:32:31.442
VCT Terra: channels(3) tsid(0x1cf) seclength(160)
Channel #0 name(KUSA-DT) 9-1 mod(ATSC 8-VSB) cTSID(0x1cf)
 pnum(1) ETM_loc(1) access_ctrl(0) hidden(0) hide_guide(1) service_type(ATSC TV) source_id(1)
 descriptors length(17) count(1)
  Service Location Descriptor (0xa1) length(15)

Channel #1 name(WX-Plus) 9-2 mod(ATSC 8-VSB) cTSID(0x1cf)
 pnum(2) ETM_loc(1) access_ctrl(0) hidden(0) hide_guide(1) service_type(ATSC TV) source_id(2)
 descriptors length(17) count(1)
  Service Location Descriptor (0xa1) length(15)

Channel #2 name(NBC Uni) 9-3 mod(ATSC 8-VSB) cTSID(0x1cf)
 pnum(3) ETM_loc(1) access_ctrl(0) hidden(0) hide_guide(1) service_type(ATSC TV) source_id(3)
 descriptors length(17) count(1)
  Service Location Descriptor (0xa1) length(15)

It seems to be several channels in my setup:
grep 'Could not find channel' /var/log/mythtv/mythbackend.log | sed -r 's/.+Could//'|sort -u
 not find channel 12_1 in TVCT
 not find channel 14_1 in TVCT
 not find channel 20_1 in TVCT
 not find channel 2_1 in TVCT
 not find channel 23_1 in TVCT
 not find channel 25_1 in TVCT
 not find channel 28_1 in TVCT
 not find channel 31_1 in TVCT
 not find channel 38_1 in TVCT
 not find channel 41_1 in TVCT
 not find channel 4_1 in TVCT
 not find channel 50_1 in TVCT
 not find channel 5_1 in TVCT
 not find channel 59_1 in TVCT
 not find channel 6_1 in TVCT
 not find channel 7_1 in TVCT
 not find channel 9_1 in TVCT

I know 6-1 is a bit weak, but not all of the others.

Here is the output from that watch command, but I am not sure what it is really saying:
tun: ch=8vsb:479000000 lock=8vsb ss=100 snq=100 seq=100 dbg=15868-11772-1282
dev: resync=0 overflow=0
ts: bps=19394080 ut=46 te=0 miss=0 crc=0
flt: bps=8923232
net: pps=847 err=0 stop=0

[MarcRandolph (mrand)]

Was actually fixed a little while back and released on MythTV 0.23 via Ubuntu 10.04 releases
------------------------------------------------------------------------
r23344 | stuarta | 2010-01-28 14:47:48 -0600 (Thu, 28 Jan 2010) | 3 lines

Closes #6730. Reduce verbosity to VB_RECORD of a msg in
HDHRStreamHandler::RunTS(). Not needed at VB_IMPORTANT