Financial Benefit from Power Savings in an SSD
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Here is something that we talk about often but rarely calculate on a drive by drive scale. If we take an SSD versus a Winchester drive, do SSDs really cost more to operate since they draw so much less power? That means less cost at the wall, less cost from AC and potentially smaller PSUs and UPSs.
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So let's try to find some numbers. Let's try a 15K SAS 500GB drive versus an SSD. We need to figure out the difference in power draw as a starting point.
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So looks like around 6 Watts for a typical 2.5" 15K drive.
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And a somewhat typical SSD is between essentially zero and 2.6 Watts. That's problematic as the "spin down" on an SSD is nearly instant. Traditional drives need to keep moving.
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But this suggests that we can use 3W as a very safe power savings number and often a lot more.
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so if you are paying sixteen cents for power, that's about $5/year/drive. That's a minimum. Could get as high as $10. Over a five year server life that is $25 - $50 saved. If you keep the server longer, the savings continue. If you have AC to price in, that's to be considered too and could easily double that number. So savings is likely $25 - $100 per drive over five years plus the good karma for being good to the environment.
Enough to pay for an SSD? Maybe not alone, but it could be a major cost offset on a "per drive" basis. If you think of any given SSD as costing ~$50 less than it does (or really the Winchester drive costing $50 more) it might alter your thinking a bit.
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In the grand scheme of things I think there's far superior reasons to go to SSD. Not saying there's no power savings, but at the server level I can think of several things that would make the difference come out in the wash.
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I did however get some 10K SAS drives for $37 a piece with a 2 year replacement plan.
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Also keep in mind with SSD you can go with RAID 5 with the HDD you probably looking at RAID.. 10. That can be huge too.
Also there was a time we bought spindles to get IOPs... So you might see even fewer HDD for that reason.
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@johnhooks said:
I did however get some 10K SAS drives for $37 a piece with a 2 year replacement plan.
o.0 how? what size?
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@hubtechagain said:
@johnhooks said:
I did however get some 10K SAS drives for $37 a piece with a 2 year replacement plan.
o.0 how? what size?
300 gig. Amazon had some refurbished for $35. They offered a 2 year replacement plan for an extra $2.50 for each drive. Bought a few and a couple extra for that price. That way I have a couple backups and if one does I just send it back and get a replacement.
I guess they were $37.50 a piece.
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i know i'm derailing, and i'm sorry i hate myself for it. but there are plenty of inexpensive drives on amazon!!!
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=10k+sas -
@scottalanmiller said:
So let's try to find some numbers. Let's try a 15K SAS 500GB drive versus an SSD. We need to figure out the difference in power draw as a starting point.
Are we only comparing power savings, or cost per GB as well? SSDs are coming down, that's certain, but cost per GB is still in the HDD side by a long shot (for now). If it is power savings, SSD definitely has less of a draw.
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@BBigford said:
@scottalanmiller said:
So let's try to find some numbers. Let's try a 15K SAS 500GB drive versus an SSD. We need to figure out the difference in power draw as a starting point.
Are we only comparing power savings, or cost per GB as well? SSDs are coming down, that's certain, but cost per GB is still in the HDD side by a long shot (for now). If it is power savings, SSD definitely has less of a draw.
That's why comparing 500GB to 500GB for a "Watt per GB" comparison.
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@scottalanmiller said:
That's why comparing 500GB to 500GB for a "Watt per GB" comparison.
I assume we're talking average... Some HDDs are set to time out and switch to low power mode and stuff... and some folks (like me) go in and turn that off). SSDs have the advantages of not having to spin up or down. They simply draw less power.
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@dafyre said:
@scottalanmiller said:
That's why comparing 500GB to 500GB for a "Watt per GB" comparison.
I assume we're talking average... Some HDDs are set to time out and switch to low power mode and stuff... and some folks (like me) go in and turn that off). SSDs have the advantages of not having to spin up or down. They simply draw less power.
Spinning down a Winchester drive dramatically increases its chance of death. So would increase costs in other places. Not sure if that would save money over the drives lifespan or not since it easily cuts 75% of the lifespan off.
