[Wrf-users] Hardware question

[jcrosby]

That example is perfect. Thank you very much.

Jan Ploski wrote:
> wrf-users-bounces at ucar.edu schrieb am 10/27/2008 07:04:20 PM:
>
>   
>> Good afternoon,
>>
>> I am currently in the process of getting hardware quotes for a WRF 
>> server but have a question to ask you all.  How hard drive intensive is 
>> WRF? Should I be looking at 15K RPM drives, or will 10K or even 7.2K 
>> drives work well?
>>     
>
> Hello,
>
> I guess it somewhat depends on how many instances you run simultaneously 
> (all writing to the same set of disks) and how much data each instance 
> produces. The latter in turn depends on the size of your domains and the 
> history interval between snapshots. Generally, WRF is CPU rather than IO 
> bound.
>
> Maybe this example will help you: one output time slot of a 5km grid over 
> Germany with all WRF 2.2 variables included takes ~50 MB of disk space. A 
> 144h run takes 2.75 hours on 8 Opteron processors. During this run, in 
> regular time intervals, 25 slots of 50 MB each are written to disk 
> (assuming a 6 hour history interval). So a rather low average data 
> throughput is needed (< 1MB/s). It remains far below the disk bandwidth 
> even if you reduce the history interval to as low as 0.5h. That said, with 
> more output the relative delay caused by disk IO increases, as it does 
> when you use more processors per run. I imagine you could also get 
> contention if you have multiple runs trying to write to the same disk at 
> the same time.
>
> For a more detailed discussion see 
> http://www.wrf-model.org/PRESENTATIONS/IO/WRF_IO_test.htm
>
> Regards,
> Jan Ploski
>
> --
> Dipl.-Inform. (FH) Jan Ploski
> OFFIS
> FuE Bereich Energie | R&D Division Energy
> Escherweg 2  - 26121 Oldenburg - Germany
> Phone/Fax: +49 441 9722 - 184 / 202
> E-Mail: Jan.Ploski at offis.de
> URL: http://www.offis.de
>   


-- 
Joseph Crosby
Network Administrator
Scotia Weather Service Inc.
netadmin at scotiaweather.com
-----------
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