You are missing my point. Even the best
case stat, no matter how you twist it in your favor, is based on distances
from yesterday. New servers are much smaller, require shorter interconnect
distances. I wish you could come to see the room where current #8 on
the top500 list of supercomputers is (Rpeak 114 GFlops), maybe you'll understand
then.
Instead of trying to design something
that uses more power and goes unnecessarilly longer distances, we should
focus our effort towards designing energy efficient, small footprint, cost
effective modules.
Regards,
Petar Pepeljugoski
IBM Research
P.O.Box 218 (mail)
1101 Kitchawan Road, Rte. 134 (shipping)
Yorktown Heights, NY 10598
Please respond to
Frank Chang <ychang@VITESSE.COM>
To
STDS-802-3-HSSG@LISTSERV.IEEE.ORG
cc
Subject
Re: [802.3BA] Longer OM3 Reach Objective
Petar;
Depending on the sources of link
statistics, 100m OM3 reach objective actually covers from 70% to 90% of
the links, so we are talking about that 100m isnot even close to 95% coverage.
Regards
Frank
From: Petar Pepeljugoski [mailto:petarp@US.IBM.COM]
Sent: Friday, March 14, 2008 5:09 PM
To: STDS-802-3-HSSG@listserv.ieee.org
Subject: Re: [802.3BA] Longer OM3 Reach Objective
Hello Jonathan,
While I am sympathetic with your view of the objectives, I disagree and
oppose changing the current reach objective of 100m over OM3 fiber.
From my previous standards experience, I believe that all the difficulties
arise in the last 0.5 dB or 1dB of the power budget (as well as jitter
budget). It is worthwhile to ask module vendors how much would their yield
improve if they are given 0.5 or 1 dB. It is responsible for most yield
hits, making products much more expensive.
I believe that selecting specifications that penalize 95% of the customers
to benefit 5% is a wrong design point.
You make another point - that larger data centers have higher bandwidth
needs. While it is true that the bandwidth needs increase, you fail to
mention is that the distance needs today are less than on previous server
generations, since the processing power today is much more densely packed
than before.
I believe that 100m is more than sufficient to address our customers' needs.
Sincerely.
Petar Pepeljugoski
IBM Research
P.O.Box 218 (mail)
1101 Kitchawan Road, Rte. 134 (shipping)
Yorktown Heights, NY 10598
I am a consultant with over 25 years experience in
data center
infrastructure design and data center relocations including in excess of
50
data centers totaling 2 million+ sq ft. I am currently engaged in
data
center projects for one of the two top credit card processing firms and
one
of the two top computer manufacturers.
I'm concerned about the 100m OM3 reach objective, as it does not cover
an
adequate number (>95%) of backbone (access-to-distribution and
distribution-to-core switch) channels for most of my clients' data centers.
Based on a review of my current and past projects, I expect that a 150m
or
larger reach objective would be more suitable. It appears that some
of the
data presented by others to the task force, such as Alan Flatman's Data
Centre Link Survey supports my impression.
There is a pretty strong correlation between the size of my clients' data
centers and the early adoption of new technologies such as higher speed
LAN
connectivity. It also stands to reason that larger data centers
have
higher bandwidth needs, particularly at the network core.
I strongly encourage you to consider a longer OM3 reach objective than
100m.
Jonathan Jew
President
J&M Consultants, Inc
jew@j-and-m.com
co-chair BICSI data center standards committee
vice-chair TIA TR-42.6 telecom administration subcommittee
vice-chair TIA TR-42.1.1 data center working group (during development
of
TIA-942)
USTAG representative to ISO/IEC JTC 1 SC25 WG3 data center standard adhoc