> >> effective in some cases. However, the bulk file transfer rates for > >> very large files via FireWire 400 (1394a) is significantly faster > >> than 1000baseT and FireWire 800 (1394b) is more than 240% faster > >> that GigaBit EtherNet. > > > > can you show some references for this? it's hard to understand why > > a 400 Mbps connection would be "sigificantly faster" than a 1000 Mbps > > connection. or are you talking mainly about shortcomings in some > > platform's drivers/stack? > > Easiest, simplest reference is this image: http://unibrain.com/ > products/assets/FireNET5.jpg
thanks. to me, it looks like the device can manage at most ~24 MB/s, and both GBE and FireNet can saturate it. that's not too surprising, since GBE's peak theoretical is 125 MB/s, and if you're getting less than say 60, you're doing something wrong (85 is reasonable.) > ... or read the whole report at bottom > of: http://unibrain.com/products/driverapi/firenet.htm certainly appears to be saturating because of the disk, not the interconnect. a P4/1.7 is circa -5 years, and in those days 23.4 MB/s wasn't atrocious. now, ~50 is about the least you can expect from a single disk, and that's not enough to saturate GBE. > Note that for large files, the FireWire network bulk file transfer > rates can exceed GigaBit performance. definitely not shown on those pages... > The above reports (arguably > promotional) are for FireWire 1394a (400 Mbits / second). When > similar tests are run on FireWire 1394b (800 Mbits / second), > performance can exceed 240% of network bulk file transfer (write > times) of GigaBit EtherNet. well, that's what you said before, and I'm still asking for some indication its true. I'm mainly curious about the 240% part. oh, wait, are you just dividing 24 MB/s by 10 MB/s in the table at the bottom? that's silly. > Why is it comparable to or faster from a processor running at around > 40% of GigaBit processor speeds? Processor efficiency FireWire has a > 32-bit "risc" type microprocessor, is peer to peer in hardware / > firmware and has other lean architecture features. (Small address > space, data frame large = more efficient data packet over double > duplex connections.) that's nice marketing-speak, but content-free, I'm afraid. > Future: there are prototypes of FireWire 1600 and 3200 operating over > fiber and using multiple "colors" ... using two fibers (duplex), > multiplexed by frequency discrimination (4 or 8 channels) using the > same FireWire 800 (Texas Instruments chips) ... comparable to ~~ > 64000baseT ... and the involved engineers say they can stay ahead of > Moore's Law beyond several more years. OK, I get the point. though I have to say I really don't expect optical WDM firewire to make any difference ;) what's the latency of a typical 1394 switch? are they all store/forward? are they all full wirespeed (in internal bandwidth)? what's the max fanout? I'd personally love to see something better in every way than GBE/10GE, but just don't see it happening. no, please, don't suggest IB :) _______________________________________________ Beowulf mailing list, [email protected] To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
