[mythtv-users] Pixelation/Bad Recordings HDHR Prime -- I am at my wits end

[Captain Hook]

On Fri, Sep 13, 2013 at 6:54 PM, Captain Hook <captainhookzero at gmail.com> wrote:
>
>
> On Friday, September 13, 2013, Frank Feuerbacher wrote:
>>
>> On 13-09-12 02:41 PM, Captain Hook wrote:
>>
>> <Snip>
>>
>> I know you can use RDM devices, but it doesn't seem to easily allow me
>> to do this with onboard storage.  There are options for iSCSI/SAN
>> devices, but I see in the link it may be possible, although it seems
>> unclear if they've actually added an add-in controller card or not.
>>
>> I am using virtual disks, yes.  They are added through vSphere which
>> then carves up the physical disk and creates VMDKs presented to my
>> VMs.
>>
>> I've run a few benchmarks against these disks in the VMs and I don't
>> really see much in the way of poor performance.  It is my
>> understanding that recordings really don't take much in the way of
>> performance and you can easily use even 5400 RPM drives with multiple
>> simultaneous recordings.  My recordings thus far have almost
>> exclusively been one at a time.
>>
>> I am using ESXi because I am very familiar with it and like to run
>> multiple OSes and use it's capabilities (snapshots, migrating data,
>> etc.).  I built a fairly decent performing server hoping to be able to
>> utilize one box for everything.  I am using Windows Server because I
>> run an MS shop in the day time and wanted a domain at home.
>>
>> I will consider running Ubuntu on the box and then using another
>> virtualization method, but I'd really like to avoid that if possible.
>> _______________________________________________
>>
>> I have a 4 CPU 2.6Ghz HD4000 Ubuntu box with 16G ram. It has 3 spindles
>> and I thought I was in good shape cpu, gpu and disk throughput wise.
>> However, I was a little sloppy about some of my processes and got pixelation
>> problems at times. The core problem was i/o. The machine mostly runs mythtv
>> to record 1 or 2 HD content shows (Ceton infinTV card). It also encodes
>> shows using Handbrake to .mkv.
>>
>> One spindle is my root and home filesystems (also where handbrakes writes
>> encoded movies)
>> One spindle is for mythtv and the scratch area for editing/trimming movies
>> One spindle is my movie repository for XBMC
>>
>> One of the mistakes that I made was having mythtv perform commercial
>> detection after a show was recorded instead of during the recording. This
>> triples the I/O on the same spindle. I also copied the recording to a
>> scratch area (on the same spindle) for manual trimming and Handbraking
>> instead of creating a symlink (which meant each recording had another
>> read/write pass). I also ran avidemux to build an index on each recording to
>> save me time later. Finally, I had all of these operations running at the
>> "normal" I/O and cpu priority.
>>
>> To fix, I changed commercial detection to run during recording. I changed
>> to use symlinks and I modified my job script to run avidemux with lower I/O
>> and cpu priority using:
>>
>> ionice -c idle -t /usr/bin/nice -n10 <command>
>>
>> Similarly, I lowered the priority of my handbrake scripts. I also have
>> mythbackend running with a nice value of -5. After these changes I have not
>> encountered any problems. If I did have trouble, the next thing I would do
>> is move my scratch copies of shows to another drive. This would mean that
>> the mythtv drive would have two passes over each recording one to write and
>> one to read it for copying to another drive. I don't think I have tried
>> increasing any buffer caches. It might help.
>>
>> Finally, I also had problems with the cable signal strength. I proved this
>> using the signal strength reading from my InfiniTV card. The cable company
>> concurred and added an amplifier, but the signal strength varied
>> significantly over the bandwidth so they had to add an attenuator for some
>> frequency ranges. Anyway, you do have to pay close attention to the use of
>> splitters, and you seem to have quite a few. Your cable modem probably needs
>> special handling, but all of your video devices should receive the same
>> signal strength. If you have 5 video receivers, then you are much better off
>> with a 5-way splitter (ignoring the cable modem) than to have a tree of
>> splitters. Make sure they are good splitters and not Home Depot specials.
>>
>> Good luck.
>>
>
> Great info, thanks!  I will certainly look into all of these things. I was
> just about to rebuild everything using KVM on top of Ubuntu. I may
> reconsider that. Thanks again.

Ultimately I just decided to use KVM on top of Mythbuntu and drop
VMware ESXi, as Joseph Fry suggested earlier.  This way (Myth)Buntu
has full control of the hardware and I can run my Windows Server 2012
Essentials as a VM.  This setup seems to be recording everything
perfectly, and though I have only watched two recordings from the new
setup, I have not seen a single instance of pixelation or audio drop
out.  In addition, my frontend seems to load the artwork and
recordings faster than it did before and there is no lag when
scrolling through titles that have multiple recordings like I was
experiencing on the VMware ESXi setup.  I'm even seeing Mythweb run
faster, which is likely placebo, but I will take it!

At this point it looks pretty likely that there was some sort of I/O
issue with ESXi and that was causing my problems.  I am running some
pretty intensive applications at work on ESXi and have noticed about
zero issues.  I am running all storage from five figure SANs, so I
guess that's the difference.  Perhaps the mobo controller just cannot
keep up.  In any case, looks like everything is resolved, thanks for
all of the help.