<div dir="ltr">Wanted to update this thread and find out if anyone else is seeing the same issue in 18.04.<div>With speed_limit_max dialed down to 10000 from 100000, recordings from lower bitrate OTA sources (PBS, ABC) survive, while those from higher bitrate sources (NBC, CBS) do not.</div><div>Of course at that rate, the monthly checkarray literally takes almost half the month, so I've disabled it in cron.</div><div>Has anyone else found a better workaround?</div></div><br><div class="gmail_quote"><div dir="ltr">On Wed, May 9, 2018 at 12:45 AM Robin Hill <<a href="mailto:myth@robinhill.me.uk">myth@robinhill.me.uk</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">On Tue May 08, 2018 at 08:10:31PM -0700, scram69 wrote:<br>
<br>
> On Mon, May 7, 2018 at 8:23 AM, Jay Foster <<a href="mailto:jayf0ster@roadrunner.com" target="_blank">jayf0ster@roadrunner.com</a>> wrote:<br>
> <br>
> > On 5/6/2018 4:47 PM, scram69 wrote:<br>
> ><br>
> ><br>
> ><br>
> > On Sun, May 6, 2018 at 4:34 PM, Jerry <<a href="mailto:mythtv@hambone.e4ward.com" target="_blank">mythtv@hambone.e4ward.com</a>> wrote:<br>
> ><br>
> >> On Sun, May 6, 2018 at 7:23 PM scram69 <<a href="mailto:scram69@gmail.com" target="_blank">scram69@gmail.com</a>> wrote:<br>
> >><br>
> >>><br>
> >>><br>
> >>> On Sun, May 6, 2018 at 2:26 PM, Gary Buhrmaster <<br>
> >>> <a href="mailto:gary.buhrmaster@gmail.com" target="_blank">gary.buhrmaster@gmail.com</a>> wrote:<br>
> >>><br>
> >>>> On Sun, May 6, 2018 at 4:27 PM, scram69 <<a href="mailto:scram69@gmail.com" target="_blank">scram69@gmail.com</a>> wrote:<br>
> >>>> > It's the first Sunday of the month, so I've just gone through the<br>
> >>>> first raid<br>
> >>>> > checkarray re-sync on Ubuntu 18.04, having just upgraded from 14.04.<br>
> >>>> > /etc/cron.d/mdadm runs checkarray with the --idle argument,<br>
> >>>> presumably so as<br>
> >>>> > not to kill disk performance for other processes.<br>
> >>>> ><br>
> >>>> > However, during the array check, all recordings failed with<br>
> >>>> > threadedfilewriter errors:<br>
> >>>><br>
> >>>> "Idle" has different meanings to different apps.<br>
> >>>> You might want to throttle the max i/o rate for<br>
> >>>> sync (a good value will depend on your devices)<br>
> >>>><br>
> >>>> dev.raid.speed_limit_max<br>
> >>>><br>
> >>>> is likely the sysctl to look at.<br>
> >>>><br>
> >>><br>
> >>> Thanks Gary. I still have my old 14.04 system drive mounted. Before I<br>
> >>> sysctl -w dev.raid.speed_limit_max=some_small_number, do you know where<br>
> >>> I might be able to find what the max speed limit was under Ubuntu 14.04?<br>
> >>><br>
> >><br>
> >> cat /proc/sys/dev/raid/speed_limit_max<br>
> >><br>
> >> should do it :)<br>
> >><br>
> >> _______________________________________________<br>
> >> mythtv-users mailing list<br>
> >> <a href="mailto:mythtv-users@mythtv.org" target="_blank">mythtv-users@mythtv.org</a><br>
> >> <a href="http://lists.mythtv.org/mailman/listinfo/mythtv-users" rel="noreferrer" target="_blank">http://lists.mythtv.org/mailman/listinfo/mythtv-users</a><br>
> >> <a href="http://wiki.mythtv.org/Mailing_List_etiquette" rel="noreferrer" target="_blank">http://wiki.mythtv.org/Mailing_List_etiquette</a><br>
> >> MythTV Forums: <a href="https://forum.mythtv.org" rel="noreferrer" target="_blank">https://forum.mythtv.org</a><br>
> >><br>
> >> Right - that would work if I were actually booted under my old system<br>
> > (AMD64). Unfortunately, I've upgraded both hardware (kaby lake) and OS,<br>
> > and can no longer boot up with that drive. With the drive mounted on my<br>
> > new system I can inspect and copy files, but /proc is empty.<br>
> ><br>
> > I sincerely doubt I ever changed that limit under 14.04. However, I've<br>
> > googled around for quite a while and can't seem to find what the default<br>
> > was.<br>
> ><br>
> > So I guess I'll just try a factor of ten: 200,000 -> 20,000 and see what<br>
> > happens in June...<br>
> ><br>
> ><br>
> > --<br>
> > ________________________<br>
> > "destroying the fundamental underpinnings of the broadcast television<br>
> > ecosystem"<br>
> ><br>
> ><br>
> > _______________________________________________<br>
> > mythtv-users mailing listmythtv-users@mythtv.orghttp://<a href="http://lists.mythtv.org/mailman/listinfo/mythtv-usershttp://wiki.mythtv.org/Mailing_List_etiquette" rel="noreferrer" target="_blank">lists.mythtv.org/mailman/listinfo/mythtv-usershttp://wiki.mythtv.org/Mailing_List_etiquette</a><br>
> > MythTV Forums: <a href="https://forum.mythtv.org" rel="noreferrer" target="_blank">https://forum.mythtv.org</a><br>
> ><br>
> > From my mythbuntu 14.04 system:<br>
> > cat /proc/sys/dev/raid/speed_limit_max<br>
> > 200000<br>
> > I suspect that 200000 is the default on most linux systems and that there<br>
> > are factors other than that value that are affecting you from the upgrade<br>
> > from 14.04 to 18.04.<br>
> > Jay<br>
> ><br>
> ><br>
> > _______________________________________________<br>
> > mythtv-users mailing list<br>
> > <a href="mailto:mythtv-users@mythtv.org" target="_blank">mythtv-users@mythtv.org</a><br>
> > <a href="http://lists.mythtv.org/mailman/listinfo/mythtv-users" rel="noreferrer" target="_blank">http://lists.mythtv.org/mailman/listinfo/mythtv-users</a><br>
> > <a href="http://wiki.mythtv.org/Mailing_List_etiquette" rel="noreferrer" target="_blank">http://wiki.mythtv.org/Mailing_List_etiquette</a><br>
> > MythTV Forums: <a href="https://forum.mythtv.org" rel="noreferrer" target="_blank">https://forum.mythtv.org</a><br>
> ><br>
> ><br>
> It's very strange: the disk array (raid5, 4 X 3TB) is the one constant from<br>
> the upgrade. It did not change. In fact, all I had to do was plug in the<br>
> disks, install mdadm on the 18.04 system, and the array was automatically<br>
> recognized and started.<br>
> <br>
> So I don't understand why the resync under 18.04 has such a significantly<br>
> different effect on disk performance. I even diffed the<br>
> /usr/share/mdadm/checkarray script - almost identical between 14.04 and<br>
> 18.04.<br>
> <br>
> Any idea what might have caused the change?<br>
> <br>
Probably the kernel version. IIRC, there were changes made to the RAID<br>
code to improve the performance for SSDs, but which lead to higher<br>
impact during rebuilds.<br>
<br>
Cheers,<br>
Robin<br>
-- <br>
___ <br>
( ' } | Robin Hill <<a href="mailto:myth@robinhill.me.uk" target="_blank">myth@robinhill.me.uk</a>> |<br>
/ / ) | Little Jim says .... |<br>
// !! | "He fallen in de water !!" |<br>
</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature">________________________<br>"destroying the fundamental underpinnings of the broadcast television ecosystem"</div>