Hi everyone,
I'm considering building a master backend to serve 2-3 frontend only machines. I plan on using 4 different tuners for both SDTV and HDTV recording (1 x HD-3000, 2 x Air2PC rev 02, 1 x PVR-150). This MBE will have 1 GB RAM and a P4 3.2GHz CPU. The likelihood of 3 frontends watching recordings/live tv all at the same time is low, but I'd like it to be possible. My concern is with the speed of the LAN. Is a 100Mb LAN connection enough? If all 3 are pulling 1080i content, that will mean about 60 Mb of bandwith (Based on approx 20 Mb/s for 1080i -- I think that's right.) in use. My gut tells me that 100 Mb is plenty, but may be cutting it close if I ever want to expand to a 4th frontend. Anyone see a problem with 3 frontends and 100 Mb LAN? Anyone know of any other pitfalls to watch for?

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Mike
My Hardware Profile

Why not go giglan? What is your backbone and hardware? Also, jumbo frames can help as well.

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Retired KM user (R4 - R6.04); friend to LH users.

A reason not to go gigalan is the onboard lan of my mobos are 10/100. Gigalan would require a seperate card utilizing a free PCI slot. On the frontends, that's no problem, but on the master backend it may be an issue. 4 PCI are reserved for tuner cards, so I'd need a 5+ PCI slot mobo. Those are getting hard to find (P4 based anyway). I found one on eBay at a reasonable price since I first posted, so less of an issue now.

My network is a "gigabit-ready" wired network (Cat 6) with a Netgear GS108 gigabit switch between all my MythTV computers and my Debian "backup" fileserver. I'm interested in that jumbo frame info you posted. I'll look into that. Thanks.

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Mike
My Hardware Profile

The maximum throughput of a network card is generally considered to be 80%-90% of the line speed (This is due to ethernet, ip, and other networking overheads)

Which gives you 80Mb/s worst case.
20Mbs for each HDTV stream seems reasonable, but I have seen 25Mb/s.
So worst case is 3x25Mbs streams = 75Mb/s
Thats getting close but it should be ok.

If you wanted to add a 4th frontend, then you'd have to weigh up the cost of GbE over the chance of having all 4 frontends playing at the same time.

Also, while 75Mbs may be well within the transfer rate of your hard disk and associated I/O, as they're playing video from 3 different areas of the disk there will be a lot of head movement which will cause lower output rates. I don't know if it will lower them enough to affect you, but that's just something you're going to have to try and see.

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Mephi
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R5.5
Opteron 2.Ghz
1Gb Ram, 200Gb Maxtor PATA
Avermedia 771 DVB-T
Hauppauge Nova-S2 (waiting to be installed)
MS MCE2 Remote

My vote is for Gig. I only get about 30-35% utilization on the nic, but that's still 4x faster than I'd see on 100mb. At this point my limiting factor is the speed of the drive in my mbe. Anyway, since you're already resigned to pick up a new motherboard with 5 PCI slots, why not just swing for one with onboard GigLAN as well? I'd also check NewEgg before going ebay. If you watch your deals you can often buy new cheaper than ebay anyway.

My 2 cents...
Gonz

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Athlon 64 3400+ / 2G / 250G
3 x PVR250
1 x PVR150

Unfortunately, 5 PCI slot mobos are becoming extinct--at least for socket 775 P4 (Which is what I have and prefer to use). I have yet to see a reasonably priced (i.e. $50-ish) 5 PCI slot mobo for a 775 in the past few months, let alone one with GigLAN. I have found several Asus P5P800's (5 x PCI and GigLAN onboard) but the prices are around $85-$100...They're a little cheaper for "refurbished", but I don't want to take my chances on that especially when they are sold "as-is." I got burned once by that, but never again.

For the 5 x PCI slot board I just picked off eBay ($30 delivered) with an onboard 10/100 LAN, I can add the gigLAN card in my last PCI slot. I was just thinking of future tuner expansion. I suppose I can always add a HDHomeRun to the onboard 10/100 if I wanted more tuners. Of course, I'll be up against drive speed by that time.

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Mike
My Hardware Profile

you can also move a tuner to one of the front end boxes.

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R5F1 - Dell P4 2.4Ghz 500MB - PVR250 x 2 - GeForce FX 5200 - Onboard sound/NIC 80GB ATA/250GB ATA/400GB SATA

As you're probably finding, PCI-express is taking over from the old PCI slots. One option if you can find a board with 4xPCI and a PCI express slot is a PCI GbE card, such as this:

http://industrialcomponent.com/aaxeon/lan1400.html

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Mephi
-----------
R5.5
Opteron 2.Ghz
1Gb Ram, 200Gb Maxtor PATA
Avermedia 771 DVB-T
Hauppauge Nova-S2 (waiting to be installed)
MS MCE2 Remote

Yes, I got a new ASUS P5K-V mobo for a second KM box.. down to three PCI slots (and has two PCIe slots), and the built-in LAN is a PCIe gigabit .. probably marvel. I'll warn that there are some challenges to getting this to work with KM, once I get there, I'll report! (not lookin' pretty! R5E27 doesn't see the netcard. I'll likely pop in a PCI netcard to get it going!)

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// Brian - Hardware:
ASUS P5P800 - P4 3Ghz, 500 GB PATA HD
ASUS P5K-V - P4 Core2 Duo, 500 GB SATA HD
Hauppauge PVR-350, IR Blaster, Comcast Digital Cable
http://tech.groups.yahoo.com/group/KnoppMyth/
KnoppMyth R5F27 >> R5.5

If you're looking for a new mobo anyway why not make onboard GigE a requirement. I have a fairly old nForce4-based mobo which actually came with Dual GigE on board. Both ports "just work" for me, although I've never actually verified the second.

So, that's what I have done. Strange, after popping that in, it shows that I have an eth0 and an eth1. I'm up and running on the PCI netcard. I might just try and yank out the card and just see if it comes up on the built-in netchip.

When the time comes to add another Frontend box why not consider moving the motherboard/processor/etc in your current backend to the new frontend, and purchase a new motherboard/cpu/etc for your new backend machine (one with GB lan). You'll end up with a backend that can dish out at GB speeds, and frontends that are only pulling at 100mb speeds which should be fine.

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Currently Running:
Too lazy to update this with my current hardware, I'll redo it during my next install =)

Actually, at this point in time.. I've got two independent Knoppmyth boxes. I'd like to join them via the 1GB connection for cross viewage! It has been suggested to designate one of them as the master database, and point the other box to it.
This should work...
from the second mythbox

yourpassword = mysql password on master mythbox
masterip = ip address on the master mythbox



Connecting each machine to the internet via 10/100 netcard should be easy.. but can I connect the two mythboxes to eachother via the 1GB netcard.. ie. private high speed network?

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// Brian - Hardware:
ASUS P5P800 - P4 3Ghz, 500 GB PATA HD
ASUS P5K-V - P4 Core2 Duo, 500 GB SATA HD
Hauppauge PVR-350, IR Blaster, Comcast Digital Cable
http://tech.groups.yahoo.com/group/KnoppMyth/
KnoppMyth R5F27 >> R5.5