Filed under: Hardware
Solid-state hard disks don't help battery life
In an interesting test by the folks over at Tom's Hardware, solid-state drives (SSDs) suck more power than their platter-based counterparts. Why should you care? Because the MacBook Air features an SSD in its higher-end configurations.
Tom's looked at four different SSD models, and compared them with a 7,200 RPM disk of the same size. One disk, from Crucial, touted its "low power consumption" in marketing materials. However, the disk reduced its test laptop's battery runtime from seven hours to six hours. Ouch.
SSDs are significantly faster, of course, but the idea that they consume less power appears to be false. As manufacturers develop thinner and thinner sub-notebooks, power consumption can only become more and more important.
Update: Many commenters are pointing out problems with how Tom's Hardware conducted the test. Peter cites a comment from our sister blog Engadget that says "The TH article was, as usual, significantly flawed. The benchmark they used to test battery life restarts itself after each completion, doing so until the battery is dead. However, the article did not report how many times the benchmark was able to run on the SSD vs. the mechanical HD." Commenter Greg recommended this Anandtech article as a counterpoint to this one.
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Reader Comments (Page 1 of 2)
Greg said 8:54PM on 7-02-2008
This article is such a lie; I wish sites would stop posting it. Tom's Hardware is an incredibly disreputable site among tech sites like it, and there's a reason for it. The way they've set up this test (as best I can tell, they don't document it very well at all), they've simply set up a loop of a benchmark and let the laptop run out its battery. Why is this bad? Because the faster drives do MORE WORK in LESS TIME. It's not even remotely indicative of a real workload. For a more realistic test, consider the one done by AnandTech on the Macbook Air (http://www.anandtech.com/mac/showdoc.aspx?i=3226&p=16) in which the SSD added 11-17% usable time to the battery life.
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homagetogorto said 9:13PM on 7-02-2008
Ha! I love the second paragraph: "Could Tom’s Hardware be Wrong? No, our results are definitely correct."
Or, "No, really! Cross my heart and hope to die!"
mentalsticks said 9:20PM on 7-02-2008
Hmmm.... sounds convincing, I must say.
kleinias said 10:57PM on 7-02-2008
You certainly raise a very good point, it does seem like they should have taken into account how much work the ssd can do relative to a hd (in the same amount of time).
Dan said 11:57PM on 7-02-2008
I was wondering if anyone was gonna catch that detail. The article was retarded more or less. Obviously the battery was gonna die a bit quicker if it has to reload the test a whole lot more to which its gonna access the cpu even more.
They didnt do their hw on this one and just wanted to sound like they came on to a new discovery which ended up being pure crap.
Hell I have the Dell XPS 1330 with the 64gb ssd (got a good price at 25% with a coupon) and the battery is f#$king solid at usual 4 hours and 40 minutes ( extra large battery..which isnt even large honestly) with doing work, web/wifi. and playing a few oldies like doom, quake 2, and warcraft 3. The ssd has been a champ as my friend has the hdd version (same build) and battery last around only 3 hours and 15 minutes.
Brian Puccio said 7:50AM on 7-03-2008
I agree, Tom's methodology leaves a lot to be desired.
I wish TUAW, instead of blindly excerpting and quoting would read the entire thing, think about it for a second and ponder "does this make sense?" before posting.
bobertoq said 8:59PM on 7-02-2008
What the heck is a solid-state hard disk? I didn't know such things existed. Solid State Drives DO improve battery life. This article is doohickey.
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dagamer34 said 9:15PM on 7-02-2008
Aye, the hard drive is often the slowest part of the computer. If the CPU has to spend more time idling waiting for data (therefore decreasing power draw), then it's gonna look like normal magnetic hard drives are better for battery life.
A solid state hard drive is better for battery life BECAUSE it gets data to the CPU faster, thus the CPU can idle faster. For those that don't know, CPU's take up much more power than hard drives ever will.
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Peter said 9:17PM on 7-02-2008
Copied from a post on Engadget:
I'll be less vague than Bob. The TH article was, as usual, significantly flawed. The benchmark they used to test battery life restarts itself after each completion, doing so until the battery is dead. However, the article did not report how many times the benchmark was able to run on the SSD vs. the mechanical HD.
The reason this is a critical flaw is that, as their own graphs show, the performance of the SSD was substantially better than the other HD. With a slower drive, the CPU spends a larger proportion of time in idle mode, as the system is blocking on IO, waiting for the slow drive to return data.
With the faster SSD, the CPU spends less time idling. It is using more power, but also doing more work. If TH had reported the number of times the benchmark ran on each machine, we would have seen the SSD machine run the benchmark many times more than the mechanical drive. Their conclusions are flat-out wrong.
The whole exercise was very silly to begin with. An SSD draws less power in use than a mechanical drive does while idle. Of course it will improve, or at least not effect, battery life. The article you reference is just another sad example of the decade-long slump Tom's Hardware has faced.
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Simon Arch said 9:37PM on 7-02-2008
The sad thing is this will now become the "conventional wisdom" despite its inaccuracy. Me, I want cheap space. SSDs can't deliver that yet. I can buy a 320gb 2.5" hard drive for my MacBook for $130 from NewEgg. You can't even by SSD units over 64gb right now (or have the 128gb units shipped?) and they cost around $800-$900. I don't care what kind of power savings might be associated with SSDs; any money I might save in energy costs will be more than overwhelmed by the initial outlay for the drive. That 320gb drive might eat up more energy over its lifetime, but its overall price will still be lower than the SSD.
I hope SSDs will eventually come down in price and expand in capacity to where they CAN be viable hard drive replacements for mainstream users. The MacBook Air and its Windows-based brethren might represent the first steps toward that goal. In the meantime I'll keep using physical disks.
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mentalsticks said 9:49PM on 7-02-2008
actually, i read a post on engadget today about 128gb ssds shipping for $479: http://www.engadget.com/2008/07/01/ocz-reveals-core-series-sata-ii-2-5-ssds-128gb-for-479/
Simon Arch said 10:01AM on 7-03-2008
That's good to know. In a couple years, who knows? But sadly that's still outside my price range.
Bassir said 12:26AM on 7-03-2008
Damn right "optional".
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Casassovici said 3:08AM on 7-03-2008
Just thrown away thousand bucks for that on my macbook air... life sux ! sure I can get a hit with that one ... http://lifesuxdaily.com
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Ethan said 4:47AM on 7-03-2008
I saw links to buy hard drives on the right. I was so shocked by the article I just had to buy seven.
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Jash Sayani said 5:48AM on 7-03-2008
Whats the difference between IDE / ATA / SATA / Solid State ?
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conigs said 6:51AM on 7-03-2008
Well, fits off, you're mixing your tech. That's like saying "What's the difference between a road, street, highway, and Lexus?"
Getting away from the car analogies, IDE and ATA are essentially the same standard for hooking up drives (whether CD/DVD or HD). SATA is the successor to ATA. The main benefits are faster transfer and smaller cables.
Think of solid state as a really large flash drive that replaces your hard disk.
Greg said 7:21AM on 7-03-2008
IDE and ATA are two terms for the same thing. They're a protocol for transmitting data between a drive and the motherboard defining everything from the type of connectors used to the way the information is encoded and sent along that connecter. SATA is serial ATA, and is a newer protocol that can transmit data more quickly.
A solid-state drive is a drive with no moving parts; it's essentially a big flash drive like you have on usb thumb drives. This is as opposed to the normal hard drives, which consist of magnetically active platters which are read and written to by a little magnetic "head" that moves on a swivel arm while the platters themselves spin.
CajunLuke said 7:39AM on 7-03-2008
IDE/SATA/ATA are the connectors you use to plug the drive into the rest of the computer.
Solid State drives use Flash memory (like the iPod nano) to store information, as opposed to normal drives that use a spinning magnetic disk.
Aaron said 12:42PM on 7-03-2008
Since this was performed under a Windows machine, this isn't exactly correct for Macs.
Windows accesses the hard drive constantly and less efficiently than a Mac. OS X uses way less hard drive resources than the standard Windows machine. This article is flawed.
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