[Beowulf] Upgrading to gigabit

Jeffrey B. Layton laytonjb at charter.net
Fri Apr 22 14:15:59 PDT 2005


   Can you be more specific? For example, N-body simulations.
Also, how many nodes are you planning to use?


> Hi Jeff,
> We are planning on running some simulations for physics on these for 
> now, but the rest is still somewhat open ended.  Would a task such as 
> this warrant the use of gigabit?  Given the price it might almost be 
> worth it either way.  Thanks again.
> -Timo
> At 10:19 AM 4/22/2005, Jeffrey B. Layton wrote:
>> Timo Mechler wrote:
>>> Hi all,
>>> I will be setting up a small cluster using some older servers very 
>>> soon.  They are IBM Netfinity 4000R's with 2x PIII 750mhz, 1024mb 
>>> ram, 2 x 9.1 SCSI hdd, and 2 x 10/100mbit onboard LAN.  Would we see 
>>> a performance increase by upgrading these to gigabit?  Or would it 
>>> be a waste of time and resources?  Thanks in advance for your help.
>> Hah! I'm going to beat rgb to the gun even though I'll be writing
>> considerably less :)
>> What application(s) do you currently run on the cluster? This
>> is the proverbial $64 question. If the applications are bottlenecked
>> by networking then you could see a huge leap in performance.
>> If the apps are bottlenecked by CPU performance, then you
>> will not likely see a big boost in performance (although NFS
>> performance would improve greatly using GigE).
>>   How many servers do you have? The 32-bit, PCI, Intel GigE
>> NICs are pretty good and inexpensive (less than $30). Plus you
>> could use something like an SMC 8505T (5-port) or 8508T
>> (8-port) GigE switch that will give you jumbo frames, for a
>> pretty low cost (the 8508T is about $100).
>>   There are other options as well. Since you have 2 FastE
>> ports, you could play with an FNN (aggregate.org/FNN/). Or
>> you could try channel bonding them.
>>   GigE is cheap enough that you could use channel bond GigE
>> and use something like MP_Lite
>> (www.scl.ameslab.gov/Projects/MP_Lite/) with your MPI codes
>> to take advantage of the bonded interface (caution: not all
>> MPI's can use channel-bonded GigE, but MP_Lite claims
>> that they can. However, MP_Lite is a subset of MPI, but it
>> captures the primary functions that most MPI applications use).
>> Enjoy! (and don't be afraid to ask lots of questions here).
>> Jeff

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