<p><br>
On Apr 23, 2013 3:24 PM, "Tom Hayward" <<a href="mailto:esarfl@gmail.com">esarfl@gmail.com</a>> wrote:<br>
><br>
> On Tue, Apr 23, 2013 at 12:44 PM, Kenneth Emerson<br>
> <<a href="mailto:kenneth.emerson@gmail.com">kenneth.emerson@gmail.com</a>> wrote:<br>
> > I have six (6) three TB drives configured in a RAID6 partition of<br>
> > approximately 9TB. On that RAID6 partition I have an LVM volume using XFS<br>
> > file system that contains all of my mythTV storage groups + music + photos +<br>
> > videos. Also on these same six drives I have RAID1 partitions that have the<br>
> > OS and boot file systems (EXT4). I have a separate SATA drive that contains<br>
> > my mythTV database. The three TB drives are slow (WD Green drives - I think<br>
> > these are 5200 RPM). Five of the drives are located on separate SATA ports<br>
> > on the motherboard and the sixth drive is in a RocketRaid external SATA<br>
> > enclosure.<br>
><br>
> That configuration will really kill your performance with seeks. Myth<br>
> works best with independent drives (but you've probably already heard<br>
> that). To mitigate your sub-optimal RAID configuration, configure a<br>
> big stripe cache and read ahead to minimize seeks:<br>
><br>
> blockdev --setra 16384 /dev/raidgroup/recordings<br>
> echo 16384 > /sys/block/md0/md/stripe_cache_size<br>
><br>
> (you'll need to redo this after a reboot)<br>
><br>
> See if this helps.<br>
><br>
><br>
> Tom</p>
<p>Thank you, Tom. I wasn't looking for (another) debate on the use of RAID with mythTV. I understand that my setup isn't optimal, but until very recently, it has been working fine. I was thinking something else has happened/changed and looking for others' experiences. Those delay writes are fairly recent-- maybe I have a drive beginning to fail. I will try your suggestion and see if it helps. Even if I wanted to, breaking the RAID array apart would be expensive and a lot of work.</p>
<p>--Ken E.<br>
</p>