<font color="black" face="Verdana,Arial,Helvetica" size="2"><font color="black" face="Verdana,Arial,Helvetica" size="2"><br>--- Original Message ---<br><br>I came across the diskless how-to on the Wiki and, while I have the
<br>entire infrastructure in place (I build both windows and Linux boxes via <br>PXE booting), I immediately thought "hey, that would definitely be QUIET". <br> <br>However, the question that goes unanswered in the wiki is about
<br>performance. Since the entire system is loading and running off of the <br>network (I've got cat-5 wired) *and* mythtv is also going over that same <br>network, doesn't that beat up on the performance? Especially since swap
<br>would also be on an NFS mounted volume... <br> <br>I'd be interested to hear about people's experiences with MythTV and a <br>diskless frontend to see if it would be a viable configuration or if it <br>is just a pipe dream..
<br> <br>Thanks! <br>-Rich<br><br>--- End Original ---<br><br>Hi Rich,<br><br>If your network is 100 Megabit-switched, you should have nothing to worry about, even if you want to stream HDTV. Consider that under most configurations, HDTV encoding will commit up to 9GB per hour of video. Nine gigabytes (or approx 9000MB) per hour is approx 150MB/min or
2.5MB/sec of data. Well, we measure data (disk size) in Bytes (big B), but network speed is usually measured in bits (or bits per second, little b). So, in order to smoothly stream HDTV to your frontend, you would need to be able to sustain 20Mb/sec (
2.5 * 8, where there are 8 bits in a Byte), which is a cinch for 100Mb-switched, assuming everything is running at full duplex. When transferring file between my machines, my network routinely sustains 80Mb/s. And since it's full duplex, that means 80Mb/s transmit and 80Mb/s receive at the same time.
<br><br>So, the bandwidth is there. Since the worst you can likely do is stream an HDTV from each frontend, the only consideration is the common network segment, which is your backend to the network switch. Say, for example, you wished to stream three HDTV streams to three different frontends. Each frontend would put 20Mb/s on its own link to the switch which would aggregate to about 60Mb/s throughput for your server. You're not likely to ever do that, but I wanted to use that as an extreme example.
<br><br>With a sufficient amount of RAM, you are not likely to have to NFS swap from the frontends, even with 256MB of memory, especially if you are doing hardware decoding. The output from come through the network interface, across the bus to the decode hardware of your video card (or chipset), so there's really nothing to buffer. Unless you have stuff running on the frontend box other than just MythTV, there should be nothing to swap either. But even if it had to, your network would have to be taxed virtually to its "knees" for you to notice it.
<br><br>I hope this helps a little.<br>-Rich.<br> </font></font>