<div class="gmail_quote">On Thu, Feb 3, 2011 at 2:44 PM, Eric Sharkey <span dir="ltr"><<a href="mailto:eric@lisaneric.org">eric@lisaneric.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div class="im">On Thu, Feb 3, 2011 at 11:40 AM, Brian Long <<a href="mailto:briandlong@gmail.com">briandlong@gmail.com</a>> wrote:<br>
> Is it generally a<br>
> bad practice to put MySQL on a SSD? I figured it would provide a nice fast<br>
> DB and keep my DB separate from my recording disks, but I guess I was wrong.<br>
<br>
</div>I have my backend's MySQL db on an SSD, with the recordings on a<br>
magnetic disk, and I don't have anything like the problems you're<br>
seeing. Moving the db to the SSD seems to have been a big boost to<br>
responsiveness when it comes to searching/scheduling new recordings or<br>
bringing up the guide data.<br>
<br>
One thing I have noticed with iostat is that it tends to report<br>
elevated numbers on its first invocation, which is why I always give<br>
it a repeat interval (usually 2 seconds) and watch until it appears to<br>
be at a steady state.<br>
<br>
I have comm flagging going on right now and here's what I see<br>
(/dev/sda is my SSD):<br>
<snip><br>
So I think something is seriously misconfigured on your system.<br></blockquote><div><br>Yes, I didn't dig deep enough and it's not MySQL slamming my SSD; it's the mythbackend logging to /var/log which is also on my SSD. I tried tuning MySQL and moving /var/lib/mysql to spinning disk and noticed the SSD was still 99% utilized. Then I noticed my mythcommflag job was endlessly logging the following types of errors:<br>
2011-02-03 15:10:43.547 AFD Error: Unknown decoding error<br>2011-02-03 15:10:43.564 [h264 @ 0x37412f7ec0]decode_slice_header error<br>2011-02-03 15:10:43.583 [h264 @ 0x37412f7ec0]no frame!<br>2011-02-03 15:10:43.583 [h264 @ 0x37412f7ec0]get_buffer() failed (stride changed)<br>
2011-02-03 15:10:43.604 [h264 @ 0x37412f7ec0]decode_slice_header error<br>2011-02-03 15:10:43.653 [h264 @ 0x37412f7ec0]no frame!<br><br></div></div>Mythbackend seems to be DOS'ing my SSD! :-) I guess I need to dig into removing that job from the queue since mythcommflag doesn't like the recording.<br>
<br>/Brian/<br>