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From: hedrick@TOPAZ.RUTGERS.EDU (Charles Hedrick)
Newsgroups: comp.protocols.tcp-ip
Subject: Re:  Ethernet Suffering
Message-ID: <8705050345.AA24910@topaz.rutgers.edu>
Date: Mon, 4-May-87 23:45:47 EDT
Article-I.D.: topaz.8705050345.AA24910
Posted: Mon May  4 23:45:47 1987
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Note that the 2-3 Mbits/sec of Ethernet traffic you report is with a
test program designed to test the network only.  However in actual
use, the majority of the high-speed Ethernet traffic is generated by
file serving.  In that case, it is limited by the speed the disks, and
the amount of lookahead done by the protocols.  I would be extremely
surprised to see the current generation of Sun file server deliver
more than 1Mbit/sec of sustained throughput.  Much to my surprise, I
find that replacing Eagles with super-Eagles does not seem to increase
the throughput available in my tests noticably. Note that these tests
involved a mix of operations, including file creating, reading,
removing, and renaming, and that the files were small or moderate in
size.  I.e.  we tried to duplicate the sorts of I/O that a typical
student mix would generate.  I have to believe that fast sequential
operations on large files would get more with a super-Eagle.  Some
other results:
  - one Eagle with one controller seemed to use about 2/3 of the CPU
	in a 3/180.
  - a second Eagle on the same controller added very little in throughput
  - a second Eagle on a second controller added about 50% in capacity.
	It seems that this was limited by CPU capacity
  - a 280 with super-Eagle did not have noticably more performance than
	a 180 with Eagle.  However we assume that the 280 would
	be able to handle two disks and controllers without running
	out of steam.  (We were unable to test this because we didn't
	have the right hardware configuration.)  It's not clear whether
	this would be cost-effective, though, when compared against
	using one Sun 3/140S per disk [a configuration which however
	is not supported by Sun.  Indeed I'm not sure that the 140S
	is even on the price sheet.]I wgets