[mythtv-users] HDHR recording truncated, maximum buffer size exceeded

Tue Jan 1 18:05:02 UTC 2013

On 01/01/2013 12:29 PM, Greg wrote:
> On 01/01/2013 11:42 AM, Joey Morris wrote:
>> Monkey Pet <monkeypet at gmail.com> wrote on Mon, Dec 31, 2012 at
>> 02:52:15PM -0800:
>>>
>>> On Mon, Dec 31, 2012 at 12:11 PM, Joey Morris <rjmorris at nc.rr.com>
>>> wrote:
>>>
>>>> I'm running 0.25.3. Twice in the past two weeks I've gotten a
>>>> truncated recording from my HDHR3. Unfortunately, I didn't check the
>>>> logs the first time, but last night I did, and the backend log
>>>> includes an error message saying the maximum buffer size was exceeded.
>>>> I've pasted that message along with a few that came right before:
>>>>
>>>> Dec 30 21:04:02 conquistador mythbackend[9516]: N Expire
>>>> autoexpire.cpp:640 (SendDeleteMessages) Expiring 15958 MB for 1501 at
>>>> 2012-12-30T17:08:00 => "NFL Football":"Green Bay Packers at Minnesota
>>>> Vikings"
>>>> Dec 30 21:04:36 conquistador mythbackend[9516]: W TFWWrite
>>>> ThreadedFileWriter.cpp:499 (DiskLoop)
>>>> TFW(/media/storage1/recordings/1171_20121230202000.mpg:72):
>>>> write(57904)
>>>> cnt 997 total 57545296 -- took a long time, 31048 ms
>>>> Dec 30 21:05:11 conquistador mythbackend[9516]: W TFWWrite
>>>> ThreadedFileWriter.cpp:499 (DiskLoop)
>>>> TFW(/media/storage1/recordings/1171_20121230202000.mpg:72):
>>>> write(57716)
>>>> cnt 2094 total 120834556 -- took a long time, 33638 ms
>>>> Dec 30 21:05:20 conquistador mythbackend[9516]: E HDHRStreamHandler
>>>> ThreadedFileWriter.cpp:216 (Write)
>>>> TFW(/media/storage1/recordings/1171_20121230202000.mpg:72): Maximum
>>>> buffer
>>>> size exceeded.#012#011#011#011file will be truncated, no further
>>>> writing
>>>> will be done.#012#011#011#011This generally indicates your disk
>>>> performance
>>>> #012#011#011#011is insufficient to deal with the number of on-going
>>>> #012#011#011#011recordings, or you have a disk failure.
>>>> Dec 30 21:05:35 conquistador mythbackend[9516]: W TFWWrite
>>>> ThreadedFileWriter.cpp:499 (DiskLoop)
>>>> TFW(/media/storage1/recordings/1171_20121230202000.mpg:72):
>>>> write(57528)
>>>> cnt 2326 total 134208688 -- took a long time, 22774 ms
>>>>
>>>> At the time of the error, Myth was writing that single recording to
>>>> disk, it was commflagging that recording, and it was possibly deleting
>>>> another recording. I say "possibly" deleting, because I don't know
>>>> whether that note means the deletion started immediately, and if so,
>>>> how long it took to complete. It had just finished (at 21:01)
>>>> recording another show, and it appears to have recorded that one
>>>> successfully.
>>>>
>>>> A few other details:
>>>>
>>>> - I'm recording to a locally attached hard drive.
>>>> - The drive is dedicated to MythTV recordings. (The OS and database
>>>>    are on a separate drive.)
>>>> - The drive is formatted as ext3.
>>>> - I didn't see anything in the system logs, dmesg, or smart results
>>>> that
>>>>    would indicate a drive problem.
>>>>
>>>> This behavior is similar to what is described in these two earlier
>>>> threads, although I didn't see anyone else reporting a file deletion
>>>> prior to the error:
>>>>
>>>> http://www.gossamer-threads.com/lists/mythtv/users/522449
>>>> http://www.gossamer-threads.com/lists/mythtv/users/524829
>>>>
>>>> The last post of that second thread mentions a patch that may help the
>>>> problem: http://code.mythtv.org/trac/ticket/11061. I think my next
>>>> step will be to try the patch, but I wonder if it would simply be
>>>> masking bigger problems in the system, like a failing drive.
>>>>
>>>> Do you think this is indicative of a failing hard drive, or do you
>>>> think the patch really is the appropriate solution? Would I be less
>>>> likely to experience this problem if I changed the drive to ext4?
>>>>
>>>> Thanks for any comments.
>>>
>>> This is a long shot, but when I had recording truncation issues, the
>>> HDHR
>>> was dropping off the network and had to continuously ping it to keep it
>>> alive.  Also why are you still on mythtv 0.25 instead of the 0.26?
>>>
>>> http://www.mythtv.org/wiki/Silicondust_HDHomeRun_Prime#Troubleshooting
>>>
>>> *My recordings are being mysteriously truncated.*
>>>
>>>     - Try increasing the network buffers: sysctl -w
>>> net.core.rmem_max=1048576
>>>     - There is a bug in certain HDHomeRun Prime tuners with the
>>> 20120405
>>>     firmware which leads to it dropping off the network, leading to
>>> truncated
>>>     recordings, broken LiveTV streams, and glitchy recordings. The
>>> workaround
>>>     is to continuously ping the
>>> HDHR<http://code.mythtv.org/trac/ticket/10414#comment:25>
>>>     .
>>>     - Check for packet loss, see the Troubleshooting section on the
>>> SiliconDust
>>>     HDHomeRun <http://www.mythtv.org/wiki/Silicondust_HDHomeRun> page.
>>>
>>
>> (Fixed top posting. See
>> http://www.mythtv.org/wiki/Mailing_List_etiquette#Bottom_post.)
>>
>> Just to clarify, this isn't a Prime. It's a "regular" hdhomerun.
>>
>> I tried the low-level check for packet loss, but it didn't produce any
>> results. The save command didn't produce a series of dots like the
>> instructions said it would. When I killed it a couple minutes later,
>> it reported 0 packets received. Watching live TV or recording
>> something works fine though, so it's obviously transmitting packets.
>> Are there other ways to troubleshoot hdhomerun network problems? I do
>> identify the hdhomerun by device ID and not its IP in mythtv-setup. My
>> hdhomerun is connected to the network via a switch.
>>
>> Also, I don't understand how networking problems would cause this
>> error. Why would MythTV complain about exceeding the buffer size when
>> writing to disk if it's having problems getting data from the tuner?
>> Wouldn't that result in too little data in the buffer instead of too
>> much?
>> _______________________________________________
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>>
> I am sure people have made it work,but I was never successful getting
> the HDHR to work off a switch...I used mine plugged into a router and
> it never failed me...Have you tried the Silicondust forums for answers?
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>
Do you have "slow delete" set in the backend? ext3 can cause a heavy
load on the drive while deleting large files, so when using ext3 you
should select "slow delete".
Peter