[rescue] u2 drive trays

Curtis H. Wilbar Jr. rescue at hawkmountain.net
Tue Aug 19 12:36:50 CDT 2003

>From: "Jonathan C. Patschke" <jp at celestrion.net>
>On Tue, 19 Aug 2003, Curtis H. Wilbar Jr. wrote:
>> OK.... but how is this different from FDDI.... if I have two FDDI
>> clients trying to throttle one FDDI server... that is still only
>> 100Mbit of bandwidth at the server, and aggregated 200Mbit of clients...
>> So how does it differ ?
>The clients don't have to fight for fair time at the fabric level.  This
>is built into the FDDI protocol and is a large portion of why Ethernet
>doesn't reach a full 100Mbit in most real-world situations.

So 100Mbit of transfer is what a client can see... which means raw
theoretical transfer on the fiber is higher.... ?????  vs ethernet
100baseTX, where 100Mbit is the physical throughput of the medium ??

>To put it another way, FDDI guarantees that each node will have time to
>speak.  Ethernet makes the switch deal with it.

true... but in FDDI your node has to wait for the token, where in 
ethernet the switch may hold your packet (store and forward) to get
it ot the host....  wouldn't the delays be theoretically similar
(assuming that the physical medium speed is identical (which I don't

>> Other than MTU, I don't see a big difference between 100baseTX switched
>> and FDDI...  in the example you cite, how is FDDI going to do any better
>> than switched 100baseTX (other than an improved MTU) ?
>If you're using NFS, SMB, AFS, AFP, or some other distributed
>filesystem, that increased MTU is enough.

I can definately see a boost with that.... wonder if any of my switches,
NICs, OSes can support larger frames for ethernet ???

>As soon as I get the DEFPA drivers working on OpenBSD/sparc64, I'll post
>benchmarks for some fairly common scenarios.


>Jonathan Patschke   )  "We're Texans.  We figure out ways to do these
>Elgin, TX          (    things..."                    --Bill Bradford
>rescue list - http://www.sunhelp.org/mailman/listinfo/rescue

-- Curt

Curtis Wilbar
Hawk Mountain Networks
rescue at hawkmountain.net

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