In a server, the processor accounts for 50% of total server power, the memory sy

Question

In a server, the processor accounts for 50% of total server power, the memory system accounts for 30%, the disk accounts for 10%, and miscellaneous components account for the remaining 10%. You have a $500 budget to upgrade your server to make it more power-efficient. You plan to either replace your memory module with a new memory module or your disk with a new disk. With that budget, you can either purchase a new memory module that consumes 20% less power than your old memory module, or a new disk that consumes 40% less power than your old disk. Which of the two will you purchase if you were only concerned with reducing your server's power consumption?

Explanation / Answer

Let's assume that the total power consumed is P.

So, the power consumed by the processor (Ppro)=PX50/100=P/2.=0.5P

Power consumed by memory system (Pm)=PX30/100=0.3P.

Power consumed by disk (Pd)=PX10/100=0.1P and the other miscellaneous componets consume power (Pmisc)=0.1P.

Now, with a budget of 500 USD, server has to be upgraded to make it more power-efficinet.

Option 1:

A new memory module is purchased. This memory module consumes 20% less power than the older memory system.

Remember, Pm=0.3P (in the previous case). So, the power consumed by the new memory module will be

Pm1=Pm-PmX20/100=Pm-Pm/4=(4/5)XPm=0.8Pm=0.8X0.3P=0.24P

So, with this upgrade, everything else remains intact and new power consumed by the memory module is 0.24P

So, total power in this case Pn1=0.5P (Processor)+0.24P (Memory)+0.1P (Disk) + 0.1P (Misc)=0.94P

Option 2:

A new disk is purchased and this new disk consumes 40% less power than the previous disk system. So, new disk power, Pd1=Pd-PdX40/100=Pd-0.4Pd=0.6Pd=0.6X0.1P=0.06P

So, total power Pn2=0.5P (Proc) + 0.3P (Memory) + 0.06P (Disk) + 0.1P (Misc)=0.96P

Since, Pn1<Pn2 and power saving is the prime objective in this case, changing the memory system will be the viable option.

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