[rescue] Gigabit Ethernet SBus & Gigabit Ethernet Sun 420R/220R

Shannon Hendrix shannon at widomaker.com
Thu Apr 24 23:02:21 CDT 2008

On Apr 6, 2008, at 10:46 , Phil Stracchino wrote:

> Steve Sandau wrote:
>> Tom "spot" Callaway wrote:
>>> On Sat, 2008-04-05 at 23:37 -0400, Joshua Boyd wrote:
>>>> On Apr 5, 2008, at 11:27 PM, Tom "spot" Callaway wrote:
>>>>> On Sat, 2008-04-05 at 23:03 -0400, Earl D. Baugh Jr. wrote:
>>>>>> Two Gigabit ethernet questions....
>>>>>> Did anybody ever make a Gigabit ethernet SBus card that ran  
>>>>>> across
>>>>>> twisted pair?
>>>>> Wouldn't that be a bit silly, since SBUS maxes out at 200 MB/s  
>>>>> (64 bit
>>>>> bus)? Or is it bridging to PCI to get around that somehow?
>>>> So, basically, you are pointing out that SBUS can do about 2.5  
>>>> times  the bandwidth that one would realistically get from GigE?   
>>>> Why is  that silly then?
>>> Ehh, I suppose. I was thinking 1000 MB/s, but that's not realistic.
>> I would hope that gigE would max out at more like 500MB/s, but I  
>> have not worked with gigE and jumbo frames enough to know.
>> 100MB ethernet maxes out at what, 70MB/s or 80MB/s under ideal  
>> conditions, or is that even too optimistic?
> It's megabits, remember, not megabytes.
> I have gotten an honest 97Mbit/s data rate across my local 100Mbit  
> network.  That's about 12 MB/s.  If GigE can manage 900Mbit/s actual  
> throughput, that's 112MB/s.  So if SBUS tops out at 200MB/s, it  
> should take GigE traffic just fine.  If that's 200Mbit/s, then GigE  
> on SBUS isn't going to work too well.  :)

On my gigabit LAN, I seem to max out usually around 20MBytes/sec.

That's going from a Mac Pro to a Dell T105.

Neither of them is using enough CPU to even show up during a transfer,  
so I'm not sure why I can't get better.

Of course, my NAS box maxes out at less than that, around 14MBytes/ 
sec, but it has a tiny 200MHz embedded CPU.

Seems to me CPU isn't the issue, nor should the bus be an issue with  
my Mac and my Dell, both of which have gigE on PCI Express.

My switch is an HP 1800 24-port, which is supposed to have 48Gbit/sec  
of bandwidth.

Shannon Hendrix
shannon at widomaker.com

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