[Beowulf] Station wagon full of tapes

Andrew M.A. Cater amacater at galactic.demon.co.uk
Tue May 26 15:22:51 EDT 2009


On Tue, May 26, 2009 at 12:26:19PM -0400, Robert G. Brown wrote:
> On Tue, 26 May 2009, Chris Dagdigian wrote:
>
> Yeah, well, stupidity is a universal problem, even in the
> government...;-) But this is why CBAs and smart people (working
> together) are so important.
>

_Especially_ in the government :)

>> I think my main interest in utility storage providers is that they can 
>> offer geographical redundancy and large capacity at efficiencies that 
>> can't be matched locally by individual institutions or even local 
>> groups of institutions. When I look at the full costs of hosting, 
>> operating and replicating the data in a local facility the numbers from 
>> the "utility" providers start to look more attractive.
>>

But you have to get the data there. A few years ago, it was cheaper and 
easier to send tapes across town by the van load - even with paying some 
poor sap to load them - than it was to send them via fibre. The 
instantaneous parallel data transfer of ~400 tapes beats anything.

The bottleneck is and ever has been getting data into the storage 
centre/data cloud and getting results back out. When the LHC gets going 
again, they were reckoning on a petabyte of data a month and so had people 
putting in racks at high speed - knowing that by the time the next to last 
rack is populated, it'll be time to rip out the first ones to put in the 
newer higher capacity lower cost drives. 

Womack's law - hi Tom :) - "disc space is cheap" and memory nearly as 
cheap. Getting the data from the memory to the disk is 
computationally expensive and getting it from the racks of disks to 
anywhere else is network expensive.

>> It will be interesting to see how this all shakes out. The rate at 
>> which raw disk cost is shrinking in price is amazing and may choke off 
>> the profit for the utility providers who have invested heavily in 
>> building out.

Let alone processor wall socket power. Dell's new Via Nano based boards 
have virtualisation on and are aimed at 3kW _per rackful_ - for China/India 
where cooling costs big money and power is uncertain. 
I've got a perfectly capable dual core 64 bit capable node under my feet. 
Processor/memory/complete motherboard - less than £60 / US$90 - but 
critically >25W. Add a laptop drive and even a 3.5" SATA and CD-ROM 
drives and it's still about 40W. [The irony - the case and drives cost 
9x the cost of the processor/memory :) ]

>
> I agree.  Moore's Law applies to more than just processors.  If only it
> applied to bandwidth....;-)
>
>   rgb
>

Is there an equivalent to Gresham's law that high bandwidth drives out 
low?

I can get a fibre connection at 50Mb constant for far less than the cost 
of 14.4k dial up back in the day considering that initially, at least, I 
had to pay per call :)

AndyC



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