I am planning to add a backend only server to my KnoppMyth setup. I have an old Asus cur-dls dual PIII motherboard with 512MB of ram sitting around that I thought about turning into the backend. I currently have two PVR-150 cards, and would like to add an additional 1-2 HD/Analog tuners soon.

I will be using a 3ware raid card with 4 160GB drives in a raid 5 array.

My plans are to then setup all diskless frontends to run off this master backend device.

Would this hardware work, or should I look at buying something with more power? I didnt really want to buy new hardware for the backend but I will if I have to.

Thanks.

if you are just doing to do SD I would think it would be ok. I think it is a little under powered for HD.

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Marty

Long live Myth and Knoppmyth!!!!!

If you have the hardware, then you've got nothing to lose by trying. Any of the things you describe should be possible from a Higher-end PIII; but I very much doubt ALL the things can be done at the same time.

The PVR-150's and at least the HD-side of your Analog/HD tuners will be providing your box with MPEG-2 streams, so very little need for CPU there. And since you're talking about backend-only, I don't worry about decoding the streams. (The PIII does not have the juice to play HD) 4 tuners is nice for bragging-rights, but I doubt you'll ever drive them all;

The 480Gb of storage (3X160 since one goes to parity) would be as little as 80 hrs for all-HD content to as much as 500 hrs for SD MPEG-4 transcoded video. Although I think transcoding on a PIII (even dual PIIIs) would be more trouble than it's worth.

I'm not sure how many frontends you're talking about; but I wonder about the disk I/O and NIC I/O from recording and serving video as well as the NFS traffic from diskless frontends.

I'd bet you could record one program wile a diskless frontend watches another, but I'm sure you couldn't record 4 programs, while 4 frontends each watch different programs.

So how hard are you planning on hitting this backend?

I plan on having two HD diskless frontends, and a single SD frontend. I know that will cause a lot of network traffic so I was thinking about getting a 1000Mb NIC, and switch for the network.

Im not doing any transcoding right now, and dont really plan on doing it later. If I wanted to could the frontends do the transcoding though?

The 3ware cards in a raid 5 array should have a pretty high disk IO, and if I get a 1000Mb NIC for the server it should have ok network IO.

I will probably be watching two live streams, and recording at least one at the same time max. One of those might be HD, but not all of them. I think Ill give it a try, and see how things go.

For point of reference: I have 1 SD and 2 HD frontends (NOT diskless), with the backend being a P4 2.4Ghz non-HT w/ 512Mb RAM, all running through a 100Mb network. No problems with network load, although we usually only have 1 HD and 1 SD frontend playing anything at any given time. I don't currently have auto-transcode enabled although I used to, didn't notice any performance issues at that time. Your expected usage sounds very similar to ours; A dual P3 system will probably handle it.

At this point I don't believe the frontends can do transcoding, but the devs may be working on something like that. You could take a look through SVN at http://svn.mythtv.org/trac/ to see what's upcoming...

I have 3 diskless frontends 2 SD and 1 HD. My backend has a 3ware card in it running raid 5 with 6 250GB drives. You should not have any I/O issues running the raid and also with a GB ethernet card in the backend. I have been able to stream 3 different things to the frontend and have something playing on the backend and the system doesn't even hesitate as far as I/O and network part.

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Marty

Long live Myth and Knoppmyth!!!!!

I think you'll be fine with your dual PIII:s as far as digital television goes, but I'm not so sure about analog, which requires certain crunch. It may be a matter of clock speed - my own PIII:s range from 500-1200MHz. I don't know if hardware encoding can be a possibility.

Putting old stuff to use is really one of the beauties of KnoppMyth - do try your existing equipment first. If you are really happy with your system you let it grow to meet your needs - one thing at a time. Beautiful!

Cheers,
/Chris

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