Just to clear something up... a 10Mbit client connected to a 100Mbit network does NOT "10x the bandwidth it is using, because it is time that matters." 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.
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....
I agree with everything else though :)
--Matt
On Tue, 2005-01-18 at 14:03 -0800, Brad Templeton wrote:
On Tue, Jan 18, 2005 at 09:54:12PM +0100, Jens Peter Vilstrup wrote: > This might be slightly OT. Sorry if I offend anyone. > I'm in the planning phase of my MythTV project, but unsure if my > planned myth-backend has enough oomph. > I have: > Tyan Tiger MP with dual 1.4Ghz Athlon XP's and 1GB of RAM. > Gbit NIC. > 2x PVR-250 cards. > Some yet-to-be-determined SATA(n) card(s), possibly RAID (that, or > software RAID). > A whole lot of harddrives. > MySQL will be on a different server. > > I want to be able to record two shows simultaneously, while watching > on two frontends, while copying files at 100Mbit to or from a client > PC... > In your experience, is this a feasible goal? More than feasible, your backend seems to be overpowered. PVR-250 effectively capture video with effectively no CPU cost, just a few percent on an Athlon 750mhz, for example. I see no reason why a single machine of just about any stripe could not do what you describe (except the software RAID, that might require some CPU) There is a network limitation. If your frontends are on the same network as the PCs that are saturating the 100mibt network, then a saturated net is a saturated net. I don't know about gbit networking but with 100mbit the rule was that a 10mbit client on the network takes 10x the bandwidth it is using, because it is time that matters. Ie. if gbit works the same, then a 100mbit client connected to the switch uses all of the switch if it is using the full 100mbit, it doesn't use 10% of the switch. Recording from pvr-x50 cards and pchdtv cards takes almost no CPU power at all. Things that take CPU power are playback (on that machine) and complex SQL queries. (For example, I have found that by putting 100 record-wishlist searches into Myth, the database takes a minute to recompute the recording table every time I make a change, but this is rather extreme.) _______________________________________________ mythtv-users mailing list [email protected] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
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-- Matt Mossholder <[EMAIL PROTECTED]> |
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