For the record, datacenter power is rarely 240. People say "240" but they really mean single-phase 208 volt, usually at 20A or 30A.

As someone else stated, NetApp hardware is auto-ranging. It will sense 110 volt/208 volt and adjust accordingly.

Remember that as per code in all 50 states, you cannot load a circuit beyond 80% of its rated capacity. That means that each of your 110 Volt 20 Amp circuits will only have 16 amps usable. Since Watts = Volts x Amps, you will have about 1760 watts available per circuit. Next you have to design with circuit redundancy in mind, such that if you should lose a circuit, the surviving circuit(s) should be able to pick up the entire load.

So using a typical rack fed by two redundant 20A circuits as an example... - Immediately reduce amperage by 20% as per code. This puts you at 16A per circuit. - Load the whole rack up to the capacity of one of the circuits in case one of the circuit pair should go down. In our example, each circuit is capable of handling 16A. Loading either of the redundant circuits beyond 16 amps means that if one circuit should go down, the other might trip the breaker.

So we stared with two 20A 110V circuits and wound up with only 16A/1760 Watts usable in a circuit redundant design! A three node VMware cluster can easily consume this much power. You can quickly see how moving from 110 to 208 volt almost doubles the amount of Wattage available in the rack (or halves the amount of Amps drawn by the equipment).

Moving from 208 to 110 is a step backwards in my opinion. With today's equipment and rack densities, 30A 208V is more realistic and I'm recommending three phase all the way to the rack for my big customers. For a Colo environment, it is usually less expensive just to rent more racks than to have them supply 30A circuits.

If you are stuck with six 110V 20A circuits, you can do the math and determine how much load you are willing place in each rack. The next step is to look at the NetApp Hardware references to determine manufacturer's maximum rated specs. I usually take 40% to 60% of this value to put me in the ballpark of what the actual load will be. Measuring your current IT load is fairly easy. You can have an electrician clamp the lines and see the actual amperage draw in real time, then you will know for sure.

I hope I have helped in some way.

Tim Hollingworth ePlus Technology Inc. 678.462.6698 (Cell) hollingworthtim (AIM/YIM)

-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Learmonth, Peter Sent: Thursday, October 14, 2010 9:34 AM To: Steve Losen; toasters@mathworks.com Subject: RE: Moving netapp hardware to different racks

Hi Steve This may have changed, but at least when they first shipped, FAS6000 series came with either a 120/240V power supply or a 240V only power supply. Anything shipped in a cabinet OR going to Europe had/has the 240V only power supply.

So, check your power supplies.

Also, ask your SE to help you with this.

Peter Learmonth Virtualization Solutions Architect

NetApp http://blogs.netapp.com/getvirtical/

-----Original Message----- From: Steve Losen [mailto:scl@sasha.acc.virginia.edu] Sent: Thursday, October 14, 2010 5:59 AM To: toasters@mathworks.com Subject: Moving netapp hardware to different racks

Greetings Toasters,

Please bear with me, I'm not an electrician.

We are constructing a new data center and we are standardizing our racks and the power feeding them. We plan to move some netapp hardware to the new data center, which is currently installed in netapp cabinets where each cabinet is powered by 4 240V 30 amp circuits.

The racks in the new data center will be powered by 6 120V 20 amp circuits each. That is less power than we have in our netapp cabinets, but we can simply put less equipment in the new racks if necessary.

I am pretty sure that this will not cause us any problems. We already have several FAS2050 controller pairs and DS14MK2 disk shelves installed in non-netapp racks plugged into 120V outlets.

Can FAS6040 and FAS3170 heads be plugged into 120V ? (I will double check the hardware specs.)

We could move the netapp cabinets to the new data center, but then we need to reserve floor space for the cabinets and run 240V circuits to them. We would rather use the new standard racks/power.

Steve Losen scl@virginia.edu phone: 434-924-0640

University of Virginia ITC Unix Support

This is also the SNIA recommendation.

Alan

Alan G. Yoder, MSEE, Ph.D. Office of the CTO, NetApp Vice-Chair, SNIA Technical Council Secretary, SNIA Green Storage Initiative Governing Board, SNIA Storage Management Initiative agy@netapp.com 408 747 1419 650 814 6498

On 10/15/10 2:21 PM, "John Stoffel" john.stoffel@taec.toshiba.com wrote:

Steve> Please bear with me, I'm not an electrician.

Better start learning now! The more you know, the better your new data center will be.

Steve> We are constructing a new data center and we are standardizing Steve> our racks and the power feeding them. We plan to move some Steve> netapp hardware to the new data center, which is currently Steve> installed in netapp cabinets where each cabinet is powered by 4 Steve> 240V 30 amp circuits.

Steve> The racks in the new data center will be powered by 6 120V 20 Steve> amp circuits each. That is less power than we have in our Steve> netapp cabinets, but we can simply put less equipment in the Steve> new racks if necessary.

You're doing it wrong IMHO, you should be moving all your gear to 240V power, because the power factor will be better and you'll spend less money on power, you'll spend less money on wiring (and with the cost of copper these days...) and you'll be able to put more equipment in a smaller footprint, which will help you save on cooling and other overhead costs.

I strongly urge you that you go back and re-think this, and you should be able to convince them to move to all 240V just from the savings in power costs.

It's more efficient, your UPS will be better able to handle the load, etc. It's amazing how quickly the savings can add up, esp if you have high power costs.

John John Stoffel - Senior Staff Systems Administrator - System LSI Group Toshiba America Electronic Components, Inc. - http://www.toshiba.com/taec john.stoffel@taec.toshiba.com - 508-486-1087