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Energy footprint of different CPUs
lammert




msg:4170357
 3:58 am on Jul 15, 2010 (gmt 0)

The current cluster of servers I'm maintaining for webserving and other purposes mainly uses multicore Intel type CPUs. The servers have been bought or leased on different times for different purposes and there are therefore some different Intel processor series in use.

When buying a server, processing power, memory, disk space and price are often the reason to select a specific configuration. But with current energy prices and limitations in data centers on the power usage per server, it is also important to look at the average power usage. A not too special server uses about 150 Watt. With a price of $0.15 per kWh, that translates to $197 per year. Prices may vary in your situations, but it is a significant amount of money. For servers in data centers you should add to that the power consumption of the cooling units to pump the heat of that server away.

The main power user in most servers is the CPU. Modern multicore processors have the ability to automatically reduce the internal clock speed when the full processing power is not needed and this lowers power usage significantly. Most web servers don't need the CPU running on maximum speed continuously anyway. All Linux servers I have running use the Munin monitor software to make graphs of all kind of system parameters during runtime. It makes it easy to tune the system configuration and decide which resources are used to their max. Some months ago I wrote a plugin to monitor the internal clock frequency of the individual cores of the processors and there are huge differences between the XEON families, which I want to share here.

The low end server model uses a dual core XEON 3065 processor of 2.33GHz. On low load, this processor steps down to 2GHz. Not a real reduction in speed. More interesting to see is that at high load, both cores are always stepped up together to 2.33GHz. This processor doesn't seem to have the option to regulate the core frequencies independently.

The second server model I watched is based on the Intel 6420 core 2 duo series running at max 2.13GHz. This processor is able to reduce the CPU frequency to 1.60 GHz. It also switches the core frequencies independently when more processing power is needed.

The third server model runs the quad core XEON 3430 with a maximum frequency of 2.40GHz. With low CPU utilization, the CPU frequency is reduced to 1.20GHz. Just as with the 6420, this model is also capable of switching the frequency of each core independently.

These results show, that the maximum processing power a CPU can deliver is no direct measure for the electrical power it consumes during life time when the CPU is not constantly under high load. Newer more expensive CPU models with better frequency control may be cheaper in the long run. Also new fabrication techniques reduce average power consumption for newer CPU models with the same specs as older CPUs. Therefore, if power consumption and electricity bills are a concern for you, it might be wise to consider looking at the current CPUs in use and upgrade the bad performers.

 

johnmoose




msg:4175711
 8:48 am on Jul 24, 2010 (gmt 0)

Thats why datacenters nowadays use virtualization to cut back on physical power consuming hardware and consolidate it all on less and less hardware, optimizing utilization and lowering power bills.

tangor




msg:4175722
 10:05 am on Jul 24, 2010 (gmt 0)

OUCH! Until Cap and Trade is codified I won't be that concerned, but yes, there are costs as regards doing business.

BillyS




msg:4175745
 11:47 am on Jul 24, 2010 (gmt 0)

OUCH! Until Cap and Trade is codified I won't be that concerned, but yes, there are costs as regards doing business.


I'm not sure what the trading of emissions credits has to do with wasting electricity. Personally, I don't need the incentive of being able to trade emissions to do the right thing by the environment.

The OP's point is a good one, as energy prices continue to increase (and they will), data centers need to look at individual components in their machines.

tangor




msg:4175754
 12:09 pm on Jul 24, 2010 (gmt 0)

data centers need to look at individual components in their machines.


Embedded in my comment, just let us say IT COSTS to be in biz these days. And for those who don't look forward, it might cost a bit more...

Sylver




msg:4175844
 5:39 pm on Jul 24, 2010 (gmt 0)

Hum, how much can be saved really?

$197 per year per server for electricity sound like a lot, but how much of it can be saved by using more recent CPUs?

Is there that much of a difference? If you can reduce the cost by half with a newer CPU (and I don't know whether this is realistic), you save about $100 per year minus the cost of replacing the CPU and the cost of disposing of the old one.

There is a fair chance that the "old" one will find its way somewhere and remain in use (a fair bit of computer equipment to be disposed off is actually given to third parties or pocketed by the staff), so I wouldn't bank on the positive effects on the environment.

And then there is the issue that CPUs are constantly improving and that less than a year from now, there will probably be more energy efficient CPUs that will make your new CPUs look like energy hogs.

It makes sense to take into account the energy cost of computer equipment but that factor can easily be overstated.

aspdaddy




msg:4175853
 5:48 pm on Jul 24, 2010 (gmt 0)

Yep, Green IT is the latest buzz. Its all those little 1U heaters that the cheap hosting companies use, most of the large DC's are now virtualising.

lammert




msg:4175861
 6:18 pm on Jul 24, 2010 (gmt 0)

The 1U heaters are indeed one of the reasons for the current focus on energy consumption per server, but I wouldn't say it's only a Green IT buzz. Until a few years ago servers with a height of 4U or 5U were common in data centers. That would give an energy consumption of a few kW at most per rack. With the reduction to 1U and 2U per server, the number of servers per rack increased significantly, and racks consuming between 6kW and 8kW are no exception anymore.

Many older data centers are simply not able to cope with that extra energy consumption per rack. Rack space providers either have to increase prices for power hungry users, or they have to leave server slots empty to prevent overload.

Regarding the CPU part of the energy consumption of servers, HP provides an energy calculation tool for their current server range which predicts the power consumption based on the actual hardware components used and the estimated server load. For the X3430 model I mentioned in the OP, the estimated total energy consumption varies between 90 and 167 Watt, depending on the load. This is for a 1U system with maxed out RAM, harware RAID controller and four disks. For a more common system with only one or two disks and without a separate RAID board, the percentual influence of the CPU on the total power consumption will be even greater.

BillyS




msg:4175875
 6:52 pm on Jul 24, 2010 (gmt 0)

Is there that much of a difference?


Let's see. One of Liquidweb's data centers can hold 25,000 servers. at $100 savings per server that works out to an annual savings of $2.5M. Over the 5 year life of a server that's $12.5M. Sounds like a lot of money to me.

J_RaD




msg:4175889
 7:13 pm on Jul 24, 2010 (gmt 0)

data centers need to start spending money bolting solar panels to their roofs as well!

Sylver




msg:4175903
 8:01 pm on Jul 24, 2010 (gmt 0)

Is there that much of a difference?

Let's see. One of Liquidweb's data centers can hold 25,000 servers. at $100 savings per server that works out to an annual savings of $2.5M. Over the 5 year life of a server that's $12.5M. Sounds like a lot of money to me.


*If* you can save 50% on the energy costs, you save $100 on energy per server. If you can save 25%, you save $50 only. Still good...

BUT for that, you need to replace all the processors now, presumably ahead of the expected replacement date.

Suppose the cost per processor is $250 (based on the low end prices listed by Intel), replacing the processors requires an upfront investment of $6.25M, plus the cost of physically replacing the processors (replacing and testing 25K units is a lot of work) and the opportunity cost, since your personnel is tied up doing the replacement, and of course the administrative costs. I wouldn't venture a guess on those costs, but I suspect it is not free nor trivial.

If you save $100 savings per server, it will take 3-4 years to break-even, and at $50 per server, you will not break even.

Additionally, the existing servers are due for replacement at a later date. It is reasonable to expect that at that time, technologies will have moved forward and that processors will be even more energy-efficient than they currently are thereby negating the earlier savings, unless you are willing to re-replace the CPUs at shorter intervals.

If you save $12.5M on energy but end up spending $20M on CPUs and related expenses, you have lost $7.5M.

What I am saying is that just because it looks like a great deal doesn't mean it is. Energy consumption should be taken into account, sure, but you have to account for ALL consequences and all expenses involved before you can say that it will save money.

incrediBILL




msg:4176198
 6:39 pm on Jul 25, 2010 (gmt 0)

you have to account for ALL consequences and all expenses involved before you can say that it will save money.


Sure, we can save a little electricity here and there in the server farms and it's safe to assume smart data centers that rent gear will already be buying more efficient gear to save on their own electricity costs since it cuts into their bottom line.

Don't forget that energy hungry CPUs also incur additional costs such as the A/C to keep it cool, more UPS gear needed to support the servers during a power outage and then there's the impact on real expensive gear like backup generators.

Just the fact that I'm using a shared resource in a large server farm instead of trying to self-host or colo my own gear is GREEN IT in the first place as it shares the same A/C, UPS gear and backup generators as thousands of other servers, making it a savings purely from an economy of scale POV.

Therefore, since I rent a server with such low monthly hosting prices, they have to be keeping all their expenses under control, including electricity, otherwise they'd go out of business and/or the price per server rental would increase significantly.

Not that saving electricity with smarter CPUs and more energy efficient boards isn't a good idea, but there are usually larger economies of saving energy to be done in any inefficient organization.

For instance, forget servers for a second, those energy efficient netbooks are more than sufficient for many workers in an office that don't need the power of a desktop and a big 24" LCD monitor.

A receptionist could just as easily type letters and send those "WHILE YOU WERE OUT" phone call notifications using a netbook than a power hungry desktop and it's more than sufficient to play solitaire between phone calls :)

BillyS




msg:4176289
 9:51 pm on Jul 25, 2010 (gmt 0)

What I am saying is that just because it looks like a great deal doesn't mean it is. Energy consumption should be taken into account, sure, but you have to account for ALL consequences and all expenses involved before you can say that it will save money.


You're right, besides the fact inefficient CPUs are heat generators, they're also better at serving web pages. I'm thinking the payback is less than two years to replace all that equipment. Unfortunately, most of these data centers have trouble raising capital (even if the payback was short) so they don't make the investment. They just wait until the next replacement cycle.

Hoople




msg:4176292
 10:13 pm on Jul 25, 2010 (gmt 0)

With 4U or 5U height servers (this wasn't so long ago '08 - '09) we did some or all of the following:

    Slowed CPU and backbus
    Unplug CD and Floppy power.
    Disable 2 of 4 PCI bay fans - moved PCI cards adjacent to remaining fans.
    Created a Power Profile to slow down or disable all unneeded on board peripherals: VGA, Parallel, Serial, Firewire, IR and USB controller.
    Disabled the above in BIOS if the option was offered.
    Converted a lot of 5-6 disk RAID 5/6 arrays to RAID 0/1 or variant preferred by the application owner (15k rpm drives replacing 7500 rpm units) A shell game of sorts was to shift the surplussed 7500 rpm drives to the spare pool for retiring servers (12 month or less remaining rack time).

incrediBILL




msg:4176336
 12:37 am on Jul 26, 2010 (gmt 0)

they're also better at serving web pages


So is CACHE which is cheap and uses low power.

inbound




msg:4177225
 11:47 am on Jul 27, 2010 (gmt 0)

The elephant in the room is mechanical hard drives, some companies use hundreds or thousands in elaborate configurations to increase the number of input/output operations per second and transfer speed (as waiting on data is the big delay for many intensive tasks).

Companies could save a lot of power and hassle by switching to enterprise solid state storage (usually pcie connected). a single one of these devices can solve the issue that people pay a lot of cash for (if it's just iops you are looking for and not loads of storage) - this means you can do more with a single box, thus utilising that cpu power to its full potential.

The CPU of choice (if you need tons of really fast memory too, up to 192GB in a dual cpu server) has to be the Xeon 56xx series or (if you have really high memory demands) there's the 75xx series (up to 1TB on a dual CPU system!)

Of course, most people don't need such systems for web serving - but there are a lot of servers out there that are inefficient that are doing number crunching and those should be power/performance optimised too.

I see a growing market for server acceleration specialists.

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