[mythtv-users] Recent "pixelation" or "glitches" in recordings (HDHR related?)
Tom Hayward
esarfl at gmail.com
Tue Apr 23 20:23:12 UTC 2013
On Tue, Apr 23, 2013 at 12:44 PM, Kenneth Emerson
<kenneth.emerson at gmail.com> wrote:
> I have six (6) three TB drives configured in a RAID6 partition of
> approximately 9TB. On that RAID6 partition I have an LVM volume using XFS
> file system that contains all of my mythTV storage groups + music + photos +
> videos. Also on these same six drives I have RAID1 partitions that have the
> OS and boot file systems (EXT4). I have a separate SATA drive that contains
> my mythTV database. The three TB drives are slow (WD Green drives - I think
> these are 5200 RPM). Five of the drives are located on separate SATA ports
> on the motherboard and the sixth drive is in a RocketRaid external SATA
> enclosure.
That configuration will really kill your performance with seeks. Myth
works best with independent drives (but you've probably already heard
that). To mitigate your sub-optimal RAID configuration, configure a
big stripe cache and read ahead to minimize seeks:
blockdev --setra 16384 /dev/raidgroup/recordings
echo 16384 > /sys/block/md0/md/stripe_cache_size
(you'll need to redo this after a reboot)
See if this helps.
Tom
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