<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Mon, May 7, 2018 at 8:23 AM, Jay Foster <span dir="ltr"><<a href="mailto:jayf0ster@roadrunner.com" target="_blank">jayf0ster@roadrunner.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div class="m_1615586681096045912moz-cite-prefix">On 5/6/2018 4:47 PM, scram69 wrote:<br>
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<div class="gmail_quote">On Sun, May 6, 2018 at 4:34 PM, Jerry
<span dir="ltr"><<a href="mailto:mythtv@hambone.e4ward.com" target="_blank">mythtv@hambone.e4ward.com</a>></span>
wrote:<br>
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<div dir="ltr">On Sun, May 6, 2018 at 7:23 PM
scram69 <<a href="mailto:scram69@gmail.com" target="_blank">scram69@gmail.com</a>>
wrote:<br>
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<div class="gmail_quote">On Sun, May 6, 2018
at 2:26 PM, Gary Buhrmaster <span dir="ltr"><<a href="mailto:gary.buhrmaster@gmail.com" target="_blank">gary.buhrmaster@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><span>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 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, 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>
</span>"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>
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<div>Thanks Gary. I still have my old 14.04
system drive mounted. Before I sysctl -w
dev.raid.speed_limit_max=some_<wbr>small_number,
do you know where I might be able to find
what the max speed limit was under Ubuntu
14.04?</div>
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cat /proc/sys/dev/raid/speed_limit<wbr>_max<br>
<br>
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<div>should do it :)<br>
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Right - that would work if I were actually booted under my old
system (AMD64). Unfortunately, I've upgraded both hardware
(kaby lake) and OS, and can no longer boot up with that
drive. With the drive mounted on my new system I can inspect
and copy files, but /proc is empty.</div>
<div class="gmail_extra"><br>
</div>
<div class="gmail_extra">I sincerely doubt I ever changed that
limit under 14.04. However, I've googled around for quite a
while and can't seem to find what the default was.</div>
<div class="gmail_extra"><br>
</div>
<div class="gmail_extra">So I guess I'll just try a factor of
ten: 200,000 -> 20,000 and see what happens in June...</div>
<div class="gmail_extra"><br clear="all">
<div><br>
</div>
-- <br>
<div class="m_1615586681096045912gmail_signature" data-smartmail="gmail_signature">________________________<br>
"destroying the fundamental underpinnings of the broadcast
television ecosystem"</div>
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From my mythbuntu 14.04 system:<br>
cat /proc/sys/dev/raid/speed_<wbr>limit_max<br>
200000<br>
I suspect that 200000 is the default on most linux systems and that
there are factors other than that value that are affecting you from
the upgrade from 14.04 to 18.04.<span class="HOEnZb"><font color="#888888"><br>
Jay<br>
<br>
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<br></blockquote></div><br>It's very strange: the disk array (raid5, 4 X 3TB) is the one constant from the upgrade. It did not change. In fact, all I had to do was plug in the disks, install mdadm on the 18.04 system, and the array was automatically recognized and started.</div><div class="gmail_extra"><br></div><div class="gmail_extra">So I don't understand why the resync under 18.04 has such a significantly different effect on disk performance. I even diffed the /usr/share/mdadm/checkarray script - almost identical between 14.04 and 18.04.</div><div class="gmail_extra"><br></div><div class="gmail_extra">Any idea what might have caused the change?<br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature">________________________<br>"destroying the fundamental underpinnings of the broadcast television ecosystem"</div>
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