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Brad,<BR>
Just to clear something up... a 10Mbit client connected to a 100Mbit network does NOT "<FONT COLOR="#000000">10x the bandwidth it is using, because it is time that matters.</FONT>" The only way to connect a 10Mbit client to a 100Mbit network is via a switch or bridge, which does rate conversion on each frame. Hench, a 10Mbit client's traffic will be converted to 100Mbit when the frame is sent out by the switch. The time in between the frames to/from the 10Mbit client is free for use by other systems. <BR>
<BR>
Now, if we are talking about something like 802.11, that's a different story.... 802.11b clients definitely have a negative impact on the 802.11g traffic, when the b and g clients are both on the same channel. This is because everything is a broadcast, and in this instance, it really is the time that matters. The 802.11g clients can't talk or be talked to while the 802.11b systems are...speaking... so...slowly....<BR>
<BR>
I agree with everything else though :)<BR>
<BR>
--Matt<BR>
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<BR>
On Tue, 2005-01-18 at 14:03 -0800, Brad Templeton wrote:
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<FONT COLOR="#000000">On Tue, Jan 18, 2005 at 09:54:12PM +0100, Jens Peter Vilstrup wrote:</FONT>
<FONT COLOR="#000000">> This might be slightly OT. Sorry if I offend anyone.</FONT>
<FONT COLOR="#000000">> I'm in the planning phase of my MythTV project, but unsure if my</FONT>
<FONT COLOR="#000000">> planned myth-backend has enough oomph.</FONT>
<FONT COLOR="#000000">> I have:</FONT>
<FONT COLOR="#000000">> Tyan Tiger MP with dual 1.4Ghz Athlon XP's and 1GB of RAM.</FONT>
<FONT COLOR="#000000">> Gbit NIC.</FONT>
<FONT COLOR="#000000">> 2x PVR-250 cards.</FONT>
<FONT COLOR="#000000">> Some yet-to-be-determined SATA(n) card(s), possibly RAID (that, or</FONT>
<FONT COLOR="#000000">> software RAID).</FONT>
<FONT COLOR="#000000">> A whole lot of harddrives.</FONT>
<FONT COLOR="#000000">> MySQL will be on a different server.</FONT>
<FONT COLOR="#000000">> </FONT>
<FONT COLOR="#000000">> I want to be able to record two shows simultaneously, while watching</FONT>
<FONT COLOR="#000000">> on two frontends, while copying files at 100Mbit to or from a client</FONT>
<FONT COLOR="#000000">> PC...</FONT>
<FONT COLOR="#000000">> In your experience, is this a feasible goal?</FONT>
<FONT COLOR="#000000">More than feasible, your backend seems to be overpowered. PVR-250</FONT>
<FONT COLOR="#000000">effectively capture video with effectively no CPU cost, just a few</FONT>
<FONT COLOR="#000000">percent on an Athlon 750mhz, for example. I see no reason why</FONT>
<FONT COLOR="#000000">a single machine of just about any stripe could not do what you</FONT>
<FONT COLOR="#000000">describe (except the software RAID, that might require some CPU)</FONT>
<FONT COLOR="#000000">There is a network limitation. If your frontends are on the same</FONT>
<FONT COLOR="#000000">network as the PCs that are saturating the 100mibt network, then</FONT>
<FONT COLOR="#000000">a saturated net is a saturated net. I don't know about gbit networking</FONT>
<FONT COLOR="#000000">but with 100mbit the rule was that a 10mbit client on the network takes</FONT>
<FONT COLOR="#000000">10x the bandwidth it is using, because it is time that matters. Ie.</FONT>
<FONT COLOR="#000000">if gbit works the same, then a 100mbit client connected to the switch</FONT>
<FONT COLOR="#000000">uses all of the switch if it is using the full 100mbit, it doesn't</FONT>
<FONT COLOR="#000000">use 10% of the switch. </FONT>
<FONT COLOR="#000000">Recording from pvr-x50 cards and pchdtv cards takes almost no CPU power</FONT>
<FONT COLOR="#000000">at all. Things that take CPU power are playback (on that machine)</FONT>
<FONT COLOR="#000000">and complex SQL queries. (For example, I have found that by putting</FONT>
<FONT COLOR="#000000">100 record-wishlist searches into Myth, the database takes a minute</FONT>
<FONT COLOR="#000000">to recompute the recording table every time I make a change, but this</FONT>
<FONT COLOR="#000000">is rather extreme.)</FONT>
<FONT COLOR="#000000">_______________________________________________</FONT>
<FONT COLOR="#000000">mythtv-users mailing list</FONT>
<FONT COLOR="#000000"><A HREF="mailto:mythtv-users@mythtv.org">mythtv-users@mythtv.org</A></FONT>
<FONT COLOR="#000000"><A HREF="http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users">http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users</A></FONT>
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-- <BR>
Matt Mossholder <<A HREF="mailto:matt@mossholder.com">matt@mossholder.com</A>>
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