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

[Joseph Fry]

>>>>>> I have a few routes I can go here; first, I could use a separate spindle
>>>>>> for
>>>>>> just my recordings (right now it is being shared with a Windows Server
>>>>>> data
>>>>>> share that sees fairly little i/o). Second, I could pop in a 60gb SSD I
>>>>>> have
>>>>>> laying around and write some recordings to that to see if it makes a
>>>>>> difference.
>>>>>>
>>>>>> Any suggestions?
>>>>
>>>>
>>>> You can also use HDHomerun commands to record and save the live streams
>>>> (that play ok in VLC), and then play them direct from disc, which might be a
>>>> quick useful test of disc I/O.  Their manual is likely to be found on their
>>>> server.
>>>>
>>>> Can also save from mythweb to disc, and play using VLC for a 2nd view. Even
>>>> play these files on another machine?
>>>>
>>>
>>> My backend is running as a VM, so I can view it through the console,
>>> but I don't have any sound.  The easiest and most prevalent signs of
>>> this issue are with the audio, so I don't think using VLC on it will
>>> work very well.
>>
>> Good point.
>>
>>> My file system is already EXT4 and I didn't use any special formatting
>>> that I am aware of, I just installed MythBuntu and let it do the rest.
>>
>> If you installed a recent OS, then most likely it aligned your sectors
>> properly... though if your using a virtual disk, I can't be sure that
>> ESX did.
>>
>>> I only have one SATA controller and I do not know of a way to allow
>>> the VM to access it directly (unless it is a SAN, which it isn't).
>>> The SCSI controller is showing up as "LSI Logic Parallel" and it did
>>> this automatically.
>>
>> Typically you can pass some devices through to a VM, meaning the host
>> doesn't access the device itself, or virtualize it for the VM....
>> instead the VM uses the device directly using the actual device
>> drivers.  I know you can do this with some devices, as folks have used
>> it in the past to access PCIe tuners... again I have never used ESX,
>> so I don't know how it's done.  If you only have one SATA controller,
>> then it's not likely to be any help to you anyway.
>>
>> A quick bit of research says that ESX calls these RDM (raw device
>> mappings), and this thread says it can be done with a sata disk:
>> http://www.vm-help.com/forum/viewtopic.php?f=14&t=1025.  Once set up,
>> ESX would essentially ignore your recording drives, instead, the
>> entire physical disk would be assigned to the VM to be partitioned,
>> formatted, etc.  In other words, it would not be virtualized.
>>
>>> I am not using RAID at all as ESXi does not recognize "fake
>>> raid"/software RAID built into the motherboard, from what I gather.
>>
>> I wouldn't think that it would... and RAID is great but would add
>> another layer of complexity, so it's good that your not using it.
>>
>>> Regarding "dynamic virtual disks" I assume you are asking if they are
>>> thin or thick provisioned?  They are thick provisioned.
>>
>> I don't use ESX, but with many VM's I have used int he past, you can
>> create "virtual" disks, or assign a physical disk to the system.  A
>> virtual disk appears as a disk to the VM, but in reality is is one or
>> more files on the host's filesystem that are either a fixed size
>> (thick) or allowed to grow dynamically to some set maximum (thin).  I
>> would attach a physical disk to the backend VM if possible rather than
>> creating a virtual disk.
>>
>>> I have dedicated and entire spindle to Myth's recordings volume, and
>>> in the meantime I will try to record from Myth to a CIFS share on my
>>> desktop to see how that works, which was a suggestion provided to me
>>> offline.
>>
>> I don't know what your Windows Server is doing for you... but if it
>> were me, I would drop ESX and install ubuntu on the server, then use
>> virtualbox, or vmware workstation, or whatever to virtualize the
>> windows server.  This way the Backend would have full access to the
>> hardware, and you could actually use it as a frontend too if you
>> desired (I do)... but you would still be able to run virtual machines
>> for other servers you needed.
>
> 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 completely understand not wanting to rebuild your server... but I
think you will find that, because you are using a VM, not much help
will be coming your way on this list.  Your running a configuration
that is not recommended due to the exact kinds of issues your facing,
and while you can likely, with time and persistence, make it work, at
this point you cannot, with any certainty, say if the issue is with
the VM, Ubuntu, or MythTV itself.

I am sure there are tools to troubleshoot ESXi performance issues,
that's where I would go next.  Most likely you need to adjust some
setting or another to ensure that the VM has priority for certain IO
related tasks... but that's just speculation.