Re: [mythtv-users] diskless backend?

[Stephen Boddy]

On Monday 10 October 2005 18:11, Sonni Nørløv wrote:
> Hi,
>
> I have a setup with a backend/frontend running on a diskless server in
> my living room, and a 24x7 server  running mysql and nfs, and the daily
> tv channel update.
>
> Main reason for this is setup is that I have no antenna at the 24x7
> server location, and did not want or needed the idle power consumption
> of the tuner card when not in use. Also I could then use the remote on
> the prv250 tuner.
>
> This setup has been running ok for over a year now, the main issue is
> that I have no mythweb on the 24x7 server unless the backend is running,
> which requires it to be booted.

Hmmm. Must admit that this is similar to my thoughts on a slightly odd 
frontend/backend configuration. I'm curious why you can't run MythWeb on your 
24x7 server though. I undestood the web pages and db updates are served by 
apache/php/mysql. Why does the backend need to running?

If the backend does have to be running, could you possibly turn the 
frontend/backend in the frontroom into a slave, then run a master backend on 
the 24x7 server without any local tuners?
-- 
Steve Boddy
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Re: [mythtv-users] diskless backend?

[Stef Coene]

On Monday 10 October 2005 23:00, Alberto Alonso wrote:
> The TV out issues where mythtv related or laptop related?
Laptop related.
I had to connet the tv and put the tv on the right input when powering up the 
laptop.  Even the, from time to time, it was not working (most of the theme 
it was not working).  I also couldn't find a command line and/or a X server 
option to enable tv-out.
I gave away one of the laptops, but I'm going to retry it again with the other 
one if I find the time.

If tv-out was working, it was a nice frontend with a build in UPS :)
And very silent of course.


Stef
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Re: [mythtv-users] diskless backend?

[Mark Cooke]

On Mon, 2005-10-10 at 09:20 -0500, Joe Harvell wrote:
> I am considering building a diskless mini-ITX frontend/backend using NFS 
> over switched 100base-T for the storage.  I would be capturing at most 
> two streams at a time and watching at most one.
> 
> Has anyone done this?  Any problems with the setup?

Dear Joe,

I have a diskless backend with a 350 and a 250 [*].  It works well here,
but I did need to tune up the NFS parameters.  2.6 kernels, big buffers,
async, tcp, nfs version 3.

I don't do playback on the backend, but I do use it for transcoding,
which does give 4 streams max (1 to the BE and 3 from the be).  You need
to be sure that your hard disks are fast enough on your storage server
to cope with this (eg raid-stripe).

You need to be sure your network cards and switch have negotiated full-
duplex 100base correctly.

> Also, when watching live TV, does the backend read from the file and 
> stream to the backend?  Or does it take what it is capturing and both 
> write it to the file and stream it to the frontend?  If it reads it from 
> the file, then is there any likelihood of the data being cached?

Not sure, but I believe it reads from the file.  There's shortcut code
to optimise out a network stream if the file is available from disk on
the frontend, but that doesn't help the diskless situation.

Cache would depend on how much ram your backend has and how far behind
live you are (~2GB/hour is my recording rate).  My backend has 1GB ram,
and the storage server 2GB.

I have very occasional trouble with sync loss if I've been plugging in
and out USB devices due to some big pauses in the kernel during that
process.

Final note - one thing I do run into is PCI bus saturation on my storage
server.  Plenty of CPU left, but everything blocks up waiting on IO.
Can really play havoc with recordings.

Cheers,

Mark

[*] Historical accident, as the primary storage server was highly
unstable with early ivtv releases.  I setup the diskless BE as a
workaround.

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Re: [mythtv-users] diskless backend?

[Sonni Nørløv]

Yes, that would be software decoding. Unless the nvidia fx5200 somehow 
is used to help out.

The frontend is doing something like this when watching live tv:

top - 12:57:27 up 7 min,  2 users,  load average: 0.93, 1.49, 0.81
Tasks: 114 total,   1 running, 113 sleeping,   0 stopped,   0 zombie
Cpu(s): 51.0% us,  4.5% sy,  0.0% ni, 40.3% id,  0.3% wa,  1.0% hi,  
2.9% si

Mem:256344k total,   251232k used, 5112k free,0k buffers
Swap:   12k total,0k used,   12k free,99284k cached

PID USER  PR  NI  VIRT  RES  SHR S %CPU %MEMTIME+  COMMAND
2206 root  15   0  166m  34m 156m S 14.0 13.9   0:45.15 X
2139 root  15   0 000 S  1.0  0.0   0:04.11 lirc_dev
2421 mythtv15   0  147m  94m  66m S  0.3 37.6   0:57.96 mythfrontend
2539 mythtv16   0  1948  992 1720 R  0.3  0.4   0:02.00 top

2511 mythtv15   0 65632  19m  34m S  0.0  7.8   0:00.75 mythbackend

Look at the total cpu usage on the frontend as the process list does not 
seam to be completely correct.
When watching xvid movies and alike it run up to about 70-80% total cpu 
usage

.
The pvr250 has an mpeg2 encoder otherwise the P3 would not be strong enough.

As to network traffic, the system report somewhere around 1Mbyte in both 
directions when watching live tv. The gives no real load on the 24x4 
server, which by the way uses lvm striping over 2 disks, and is able to 
deliver 5-8Mbytes (writing-reading) over the network.


Live tv pause, does not load the system as much as live tv watching, as 
pause does not require reading from the live buffer.


// Sonni

Alberto Alonso wrote:


Are you using software decoding on the P3 733Mhz? Can
that setup handle live TV pause?

I am thinking of having an old laptop with almost those
specs to be one of my front ends.

Thanks,

Alberto
 



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Re: [mythtv-users] diskless backend?

[Robin Gilks]

> I am considering building a diskless mini-ITX frontend/backend using NFS
> over switched 100base-T for the storage.  I would be capturing at most
> two streams at a time and watching at most one.
>
> Has anyone done this?  Any problems with the setup?
>
> Also, when watching live TV, does the backend read from the file and
> stream to the backend?  Or does it take what it is capturing and both
> write it to the file and stream it to the frontend?  If it reads it from
> the file, then is there any likelihood of the data being cached?
>

This is exactly what I'm doing.

I have a diskless sp13000 with a pvr-150 as a combined frontend/backend
next to the TV where all the terrestrial & sat cables are and a server
with all the noisy disks locked away out of earshot. Works like a charm.
I'm using standard 100M cat5 cable thru the house and even though the live
TV ring buffer is on the NFS mounted server, I have no issues at all with
it.

Since I've only got the system up in the last week, I've not done any CPU
timings but the lights on the 100M ethernet switch only twitch during live
TV when data is going both ways so its not stressed at all. I'd guess
(based on DVD & divx playback) that I'm using about 50% of the CPU time
when both back & frontends are running during live TV.

Go for it...

-- 
Robin Gilks



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Re: [mythtv-users] diskless backend?

[Alberto Alonso]

The TV out issues where mythtv related or laptop related?

Thanks,

Alberto

On Mon, 2005-10-10 at 22:52 +0200, Stef Coene wrote:
> On Monday 10 October 2005 22:20, Alberto Alonso wrote:
> > Are you using software decoding on the P3 733Mhz? Can
> > that setup handle live TV pause?
> >
> > I am thinking of having an old laptop with almost those
> > specs to be one of my front ends.
> I tried it too.  I have 2 compaq armada's (e500).  One P2, 300 Mhz and one 
> P3, 
> 450 Mhz (I think).  They both had enough horsepower, but I think there was a 
> problem with the PCMCIA bus not fast enough.  The video was choppy.  When I 
> changed the profiles so it uses MPEG4, all was fine.  I found out that a 
> bitrate aboth 5Mbps was too much.
> I ditched the project  because I couldn't get the tv-out working liably.
> 
> 
> Stef
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Re: [mythtv-users] diskless backend?

[Stef Coene]

On Monday 10 October 2005 22:20, Alberto Alonso wrote:
> Are you using software decoding on the P3 733Mhz? Can
> that setup handle live TV pause?
>
> I am thinking of having an old laptop with almost those
> specs to be one of my front ends.
I tried it too.  I have 2 compaq armada's (e500).  One P2, 300 Mhz and one P3, 
450 Mhz (I think).  They both had enough horsepower, but I think there was a 
problem with the PCMCIA bus not fast enough.  The video was choppy.  When I 
changed the profiles so it uses MPEG4, all was fine.  I found out that a 
bitrate aboth 5Mbps was too much.
I ditched the project  because I couldn't get the tv-out working liably.


Stef
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Re: [mythtv-users] diskless backend?

[Alberto Alonso]

Are you using software decoding on the P3 733Mhz? Can
that setup handle live TV pause?

I am thinking of having an old laptop with almost those
specs to be one of my front ends.

Thanks,

Alberto

On Mon, 2005-10-10 at 19:38 +0200, Sonni Nørløv wrote:
> Sure,
> 24x4 server is an old outdated P2 266Mhz with 320Mb mem, with a couple 
> of disks in a lvm setup and xfs filesystem.
> The main job of this server is acting as a personal mail and web server.
> 
> Backend/frontend is running on a P3 733Mhz with 256Mb mem, this seam to 
> be minimum amount of memory unless swap is required, which would spoil 
> the fun when done over nfs.
> I would not mind having a faster frontend, as there is a bit of a delay 
> when changing between the different plugins such as video and music.
> Also some of the OSD fading is not to smooth, but is still acceptable.
> 
> Joe Harvell wrote:
> 
> > Thanks for confirming this.  Could you describe your platform?  Do you 
> > have any hardware recommendations?
> 
> 
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Re: [mythtv-users] diskless backend?

[Sonni Nørløv]

Sure,
24x4 server is an old outdated P2 266Mhz with 320Mb mem, with a couple 
of disks in a lvm setup and xfs filesystem.

The main job of this server is acting as a personal mail and web server.

Backend/frontend is running on a P3 733Mhz with 256Mb mem, this seam to 
be minimum amount of memory unless swap is required, which would spoil 
the fun when done over nfs.
I would not mind having a faster frontend, as there is a bit of a delay 
when changing between the different plugins such as video and music.

Also some of the OSD fading is not to smooth, but is still acceptable.

Joe Harvell wrote:

Thanks for confirming this.  Could you describe your platform?  Do you 
have any hardware recommendations?



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Re: [mythtv-users] diskless backend?

[Joe Harvell]

Thanks for confirming this.  Could you describe your platform?  Do you 
have any hardware recommendations?



Sonni Nørløv wrote:


Hi,

I have a setup with a backend/frontend running on a diskless server in 
my living room, and a 24x7 server  running mysql and nfs, and the 
daily tv channel update.


Main reason for this is setup is that I have no antenna at the 24x7 
server location, and did not want or needed the idle power consumption 
of the tuner card when not in use. Also I could then use the remote on 
the prv250 tuner.


This setup has been running ok for over a year now, the main issue is 
that I have no mythweb on the 24x7 server unless the backend is 
running, which requires it to be booted.


The servers are connect with 100mbit, so there is no issues with the 
required bandwidth.


regards
Sonni



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Re: [mythtv-users] diskless backend?

[Sonni Nørløv]

Hi,

I have a setup with a backend/frontend running on a diskless server in 
my living room, and a 24x7 server  running mysql and nfs, and the daily 
tv channel update.


Main reason for this is setup is that I have no antenna at the 24x7 
server location, and did not want or needed the idle power consumption 
of the tuner card when not in use. Also I could then use the remote on 
the prv250 tuner.


This setup has been running ok for over a year now, the main issue is 
that I have no mythweb on the 24x7 server unless the backend is running, 
which requires it to be booted.


The servers are connect with 100mbit, so there is no issues with the 
required bandwidth.


regards
Sonni



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Re: [mythtv-users] diskless backend?

[Joe Harvell]

Alex:

I agree that separating the FE an BE makes the most sense.  But there 
are a few reasons I want to do the capturing in the viewing/listening area:


The first reason has to do with the signal quality.  When I capture the 
analog S-video signal from my satellite reciever and encode it in 
MPEG-2, I am losing quality.  I realize that my style of TV watching 
will most likely change after using Myth.  But I want to be able to 
split the S-video output of my satellite reciever and have one go to the 
capture card and one go to the TV directly.  This way I retain the 
ability to watch TV (not live TV) without loss of quality.  I have a 
friend who created cabling to carry an S-video signal 50 feet using two 
QuadShield coax cables.  But I don't want to do that.  (by the way, mine 
would need to go 100 - 120 feet).


The second reason is to increase my WAF.  If I pull the satellite 
receiver away from the TV and then misconfigure or otherwise screw up my 
backend or frontend, I have to explain to my wife why she can't watch 
TV.  With a separate backend / frontend I can recover from this in an 
emergency by moving my satellite receiver back to the TV area.  If I 
have the backend / frontend at the TV area I just have to switch the TV 
input to the satellite receiver.


The third reason is that there is less cabling work. Neither my 
satellite dish antenna nor my terrestrial antenna has a cable running to 
where my desktop PC is.  I can run the cables to it.  But that is more work.


Alex Brekken wrote:

To be honest, I don't know if this would work, but even if it did - 
I'm curious to know what the benefit would be?  When watching liveTV 
you'll be doing a full roundtrip with the video-stream across your 
network.  Why not just do the capturing where the disks are and have a 
diskless frontend? 

On 10/10/05, *Joe Harvell* <[EMAIL PROTECTED] 
> wrote:


I am considering building a diskless mini-ITX frontend/backend
using NFS
over switched 100base-T for the storage.  I would be capturing at most
two streams at a time and watching at most one.

Has anyone done this?  Any problems with the setup?

Also, when watching live TV, does the backend read from the file and
stream to the backend?  Or does it take what it is capturing and both
write it to the file and stream it to the frontend?  If it reads
it from
the file, then is there any likelihood of the data being cached?


--
Joe Harvell
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Re: [mythtv-users] diskless backend?

[Alex Brekken]

To be honest, I don't know if this would work, but even if it did - I'm
curious to know what the benefit would be?  When watching liveTV
you'll be doing a full roundtrip with the video-stream across your
network.  Why not just do the capturing where the disks are and
have a diskless frontend?  On 10/10/05, Joe Harvell <[EMAIL PROTECTED]> wrote:
I am considering building a diskless mini-ITX frontend/backend using NFSover switched 100base-T for the storage.  I would be capturing at mosttwo streams at a time and watching at most one.Has anyone done this?  Any problems with the setup?
Also, when watching live TV, does the backend read from the file andstream to the backend?  Or does it take what it is capturing and bothwrite it to the file and stream it to the frontend?  If it reads it from
the file, then is there any likelihood of the data being cached?--Joe Harvell___mythtv-users mailing list
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