Need: Switch Recommendations ( > 150 ports)

Shanwu Wang shanwu at psu.edu
Sat Oct 19 14:05:32 EDT 2002


Hi Dean,

Thank you for your reminder.    We are going to trash our first generation
beowulf,  dual-PII 400 to save some space and power.  I will measure our
beowulf shelf again to make sure it is big enough, :-).  When I hunt for
desktop, I select the smallest one from Dell.  Its volume is only 1/4 of
tower case.

Because the CPU is much faster than our current systems (PIII 500 and
PIII766, a total number of 350CPUs), the network is our bottleneck.
Therefore, we select 1NIC/1CPU or channel bonding for dual-CPU node when we
still don't have enough money for Gig or myrinet.  The switch is really a
headache problem for a system in such a size.

Shanwu

-----Original Message-----
From: Dean Johnson [mailto:dtj at uberh4x0r.org]
Sent: Saturday, October 19, 2002 12:52 PM
To: shanwu at psu.edu
Cc: beowulf at beowulf.org
Subject: Re: Need: Switch Recommendations ( > 150 ports)


On Sat, 2002-10-19 at 02:48, Shanwu Wang wrote:
> We are going to purchase 150xsingle-P4 desktop, cause it is cheaper than
> 75xdual-P4 servers.  Comments are also highly appreciated, :).
>

You also have to consider the indirect costs of your approach, which are
sometimes not so terribly obvious. The big one for me has always been
space. I believe that "damn! we just have too much space" has never been
uttered by a cluster geek. Even if you have enough room, I am enough of
an optimistic/forward thinker to hope we get many more machines later. I
go by the "plan for double" method because you will quite often wish you
had. Think back to when you wondered if you would EVER use up the whole
20MB harddrive. ;-) Buying 150 singles over 75 duals will take up nearly
twice the space.

A more indirect and real money issue, is switch ports. You will have to
buy twice as many and especially at that level the price difference can
be quite dramatic. Be sure to add the price per seat for the networking
to each of the 75 extra machines to find out its true cost. Even using
cheap gigabit NICs and switches, that adds like $150 each.

There are a myriad of other items that add to the cost of having double
the amount of machines, be sure to figure them in, as best you can.

Of course, you mileage WILL vary.

	-Dean


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