From: Tim Chipman (chipman@ecopiabio.com)
Date: Mon Nov 04 2002 - 16:51:40 EST
Hi folks,
A general request for feedback from anyone who has deployed Gig-Ether
NICs (either SUN or 3rd Party) on either single CPU or SMP SunSparc
hardware:
-> in order to maintain a "solid data stream" (assume, ,<scenario a>
15megs per second, <scenario b> - 30 megs per second) -- do you
typically observe significant CPU loading (of ?? amount??) that appears
to correlate purely to feeding data to the NIC ?
-> From what I have read, it seems that Gig-Ether NICs fall (broadly!)
into
two categories:
-those which have more simple hardware, and provide no "CPU offload" for
TCP stack, "data pump" of information into the GigE pipe
-those which DO have ASIC / specific hardware on the NIC to facilitate
some CPU offloading, to alleviate CPU loading issues when feeding the
GigE pipe.
Typically, from what I can tell, the "simple" GigE nics are "cheaper"
while the ASIC-offload nics are "more expensive" (this is NOT a concern
for me, clearly - my aim is to get an idea of performance / cpu loading
issues...)
I'm inquiring on this theme specifically because we're contemplating
scaling our netbackup server from Dual-DLT35/70 drive-based-robot to a
Dual-SuperDLT 160/320 drive-based robot. The current DLT35/70 drives
officially support ~10 megs/second data stream to tape (per drive), and
we can feed easily 5 - 8 megs / second, depending on the nature of the
data being streamed, using a standard 100mbit ether NIC.
Feeding two SuperDLT drives @ 16(up to 32?) megs per second (in
parallel!) clearly requires a significantly larger pipe than we get with
typical 100mbit ether, hence these Gig-Ether questions.
Our current NBU server is a single-CPU box ; also - hence these scaling
questions WRT CPU loading footprint from streaming lots of data through
GigEther nics.
If anyone has specific comments in this vein for <any particular Gig
Ether NICs - from any vendor> -- it certainly is very welcome.
As always, I'll post a summary.
Thanks!
--Tim Chipman
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