Forgot your password?
typodupeerror
Power Data Storage

Are SSDs Really More Power Efficient? 222

Posted by CmdrTaco
from the how-will-i-green-up-now dept.
Bakasama writes "Tom's Hardware compared the power performance of several available SSD cards with a Rotating HDD that was chosen specifically for its poor power efficiency. The results seem to fly in the face of current wisdom. 'Flash-based solid state drives (SSDs) are considered to be the future of performance hard drives, and everyone seems to be jumping on the bandwagon. We are no exception, as we have been publishing many articles on flash-based SSDs during the last few months, emphasizing the performance gains and the potential power savings brought by flash memory. And there is nothing wrong with this, since SLC flash SSDs easily outperform conventional hard drives today (SLC = single level cell). However, we have discovered that the power savings aren't there: in fact, battery runtimes actually decrease if you use a flash SSD.'"
This discussion has been archived. No new comments can be posted.

Are SSDs Really More Power Efficient?

Comments Filter:
  • So if your not a laptop user and aren't currently benchmarking your drive how long will it last?

    What is the power usage for real world office/ web browsing type use?

    • by ralphgra (1311831) on Wednesday July 02, 2008 @12:12PM (#24032281)
      More tests have to be done. I have one of the earliest hard-drive MP3 players, the PhotoTainer. It has a 20GB drive, but also a CompactFlash slot. I did a timing test to see how long the battery would last running songs off both storage media. The battery lasted about 1 hour longer when using the CompactFlash memory card than using the hard drive.
    • by Sycraft-fu (314770) on Wednesday July 02, 2008 @04:36PM (#24035863)

      Even when I use something that hits my drive hard, it is far from continuous. In fact flash drives might have a chance to shine here as well as often one of the things that increases activity is the need for random access, which magnetic media isn't all that fast at. For example my harddrive works much harder than it has to when I'm doing audio mixdowns because it has to access multiple wave files at the same time. Most of the time is spent seeking from file to file, it takes comparatively little time to read the actual data needed. Flash, of course, has much faster random access. Thus for something like this it'd be loaded lighter, despite it being an "intense" use.

  • by Anonymous Coward on Wednesday July 02, 2008 @10:20AM (#24029911)

    Impossible! Those results are obviously wrong!! Now go back and do the experiment. Keep doing different experiments until we get the desired results!

    How dear you try and endanger my stock portfolio?!

    • Re: (Score:2, Funny)

      by cyfer2000 (548592)
      Are you serious, dear?
    • by hclewk (1248568) on Wednesday July 02, 2008 @12:03PM (#24032127)
      Unfortunately, the article comes to miserably faulty conclusions, and nobody seems to have noticed it. One thing everybody needs to note is this: the test that Tom's ran was designed to run a program to completion over and over again. All that Tom's came up with, thanks to that test, is that the computer with the SSD ran out of power faster. What they SHOULD have noticed, and what any sane and logical tester would have done, is counted the number of times the program RAN. A system with an SSD will run the program a significantly higher number of times because of its increased speed and lack of moving parts. With the higher number of runs, the CPU STAYS MORE ACTIVE, sucking more power out of the system and thus causing it to power down earlier. The only reason the HDD system died later is because the CPU idles waiting for it to retrieve data. The SSD may have chewed up your battery faster, but it did, comparatively, run through that program a BUNCH more times. I am willing to bet the work per watt was much better out of the SSD system than the HDD - and once again, Tom's Hardware's scientific testing system proves itself anything but.
      • by WK2 (1072560)

        When I read the summary, I thought, "Surely Tom's Hardware is doing something wrong. It is Tom's Hardware, after all." But I wasn't sure what. Thanks for pointing it out, so I don't have to RTFA.

      • by SoupIsGoodFood_42 (521389) on Wednesday July 02, 2008 @12:30PM (#24032577)

        Interesting, I didn't notice that. But one thing I did notice is that it didn't seem to take into account real world use, things such as at what point does the frequency of the extra power needed to spool up a HDD outweigh any power savings -- laptops are turned on and off a lot more than a desktop, and if the responsiveness is there, then people are going to put their computer to sleep more often to save power. None of that was taken into consideration. So technically, he may be right in some circumstances, but that might not be the way most people use them in the real world.

      • by immcintosh (1089551) <slashdot@NOspam.ianmcintosh.org> on Wednesday July 02, 2008 @01:00PM (#24033031) Homepage

        I'm not so sure your point is quite that significant. There is a graph, towards the end, that seems to be multiplying throughput by total battery life, giving a sort of "megabyte-minutes" rating for the different drives. In terms of simple hard drive throughput, this seems to indicate that the work per watt of the traditional drive was still superior (albeit by a small margin over the most expensive SDD), despite your complaint. But obviously it's not quite that simple--no real life usage would cause non-stop disk access like that.

        The claim that the CPU stays more active with the faster drive, while technically true, is a little misleading and not nearly as clear cut as you're making it out to be. The only time the CPU would really be more active with a faster drive is under circumstances where it would be waiting for some kind of blocking I/O from the drive, which in my experience (at least under mundane use) isn't all that much. Most of the time you're much more likely to be dealing with system RAM than hard drive storage during program use (unless you run out of memory and start swapping things out, but then you've got other problems).

        In short, while you point out perhaps an interesting oversight, I don't think it is quite as serious as you make it out to be.

  • Still too new (Score:5, Insightful)

    by ArcherB (796902) on Wednesday July 02, 2008 @10:21AM (#24029935) Journal

    I believe that much of the problem is that SSD's are still a new technology compared to rotating disks. Right now, engineers are more concerned with increasing capacity and just making the damn things work. These are much more important than efficiency. As time goes on and the technology gets more mature, efficiency will get more attention from engineers.

    • Re:Still too new (Score:5, Interesting)

      by drinkypoo (153816) <martin.espinoza@gmail.com> on Wednesday July 02, 2008 @10:35AM (#24030243) Homepage Journal
      The problem is apparently that they're using lots of flash without power-saving (presumably cheaper than the other kind) and they're also not turning the currently-unused chips off. I can't speak for anyone else but I spend the vast majority of my time accessing a minority of the data on my hard disk. The technology already exists to reorder disk blocks based on usage and it could easily be adapted to reduce the number of flash chips which need to be activated in an SSD. Perhaps the time to first access is consider to be too large to implement this sort of thing without on-chip power-saving features, although I doubt it would be more than a few small fractions of a second.
      • Re:Still too new (Score:4, Interesting)

        by TubeSteak (669689) on Wednesday July 02, 2008 @11:40AM (#24031679) Journal

        The technology already exists to reorder disk blocks based on usage and it could easily be adapted to reduce the number of flash chips which need to be activated in an SSD.

        Uhhh... wouldn't that defeat the purpose of using wear leveling algorithms?

        A more relevant technique would be to avoid turning on flash chips that do not have data you're accessing... but that is not as easy as it sounds when your data is (purposely) fragmented all over the place.

        • Re: (Score:3, Insightful)

          by emj (15659)

          Uhhh... wouldn't that defeat the purpose of using wear leveling algorithms?

          No not if you activate only those chips that you need to execute that read-write-write operation. But then again I'm sure if it really was as simple as switching some thing on and off then we would have good results by now..

          btw, look at the IO ops per second graph [tomshardware.com], it's interesting to note that not all SSDs are better than the disk. Though the best SSD beats disks with three orders of magnitude in webserver load..

        • Re: (Score:3, Interesting)

          by kesuki (321456)

          it's different when you're just reading data, VS writing data, and these benchmarks compared power usage while writing gobs and gobs of data.

          flash memory chips can use 5X as much power to 'write' data as they do to 'read' data, oh and hey if you're reading the same old data over and over, why not just have it in ram, and just not spin up a drive or read flash memory at all?

          oh and wear leveling can be designed around keeping as few chips powered up as possible, you just need to reserve a bit of flash memory

    • by initialE (758110)
      If this was true then SSDs are already condemned to failure. A more holistic approach is required in order to get people to want the thing in the first place. Which would then lead to more money for research. And then to faster access times, lower power levels and manufacturing costs.
      • A more holistic approach is required in order to get people to want the thing in the first place.



        There already is enough want for a SSD. The downside is most people want more then the pathetic few GBs of storage they have to offer. So when they make an affordable, say 500 GB SSD, more people will buy them leading to more SSD makers leading to faster ones and lower powered ones along with more reliable and more space.

      • A more holistic approach is required in order to get people to want the thing in the first place

        Yeah, people are never drawn in by flashy gimmicks, are they?

    • Re:Still too new (Score:4, Interesting)

      by Ilgaz (86384) on Wednesday July 02, 2008 @10:57AM (#24030701) Homepage

      Call me some guy mystified by brands but after using Seagate cheap stuff (SATA) and SCSI for years and never seen these things actually fail (besides stupid filesystems), I wait for Seagate, Fujitsu, Hitachi like known brands to ship their SSD rather than being abused by some memory vendor who has no clue about the hard disks to buy some overpriced flash memory fantasy.
      I also don't know the actual reliability of SSD too. What about journaling? Can it handle? A journal is still needed on SSD drive, what if kernel fails or OS filesystem layer goes nuts? A journal will be in same area of disk and will be written over and over millions of times.
      I could never buy the "speed" claims of SSD not just because I use very fast SCSI stuff but I actually see the horrible performance of them in my smart phone, HD Camera. It is like performance suicide if someone dares to put a very complex applications to "memory card" instead of phones built in memory.
      They are trying to ship it before it is a technology fit to general use. Much like some video sites existed while everyone had to struggle with 56K modem.

      • Re:Still too new (Score:5, Informative)

        by pipatron (966506) <pipatron@gmail.com> on Wednesday July 02, 2008 @11:14AM (#24031119) Homepage

        I could never buy the "speed" claims of SSD not just because I use very fast SCSI stuff but I actually see the horrible performance of them in my smart phone, HD Camera.

        Connect your very fast SCSI drive to your phone and see if it's still as fast.

      • You realize that the in phone memory is probably flash based too?

      • Re: (Score:3, Informative)

        by kbielefe (606566)

        I maintain a flash device driver for an embedded system as part of my job, and I have to say you have an interesting mix of misconceptions and valid points.

        First of all, I'm wondering what you think your phone's built in memory is. If it's not flash, I feel sorry for you if your battery dies. Second, the nature of flash memory makes it highly desirable to implement some form of journaling. To change one byte of a file, you have to erase a sector, then write it back with the one byte changed. It is much

      • Re: (Score:3, Interesting)

        by Eil (82413)

        Wow, um, you definitely could use some edumacation on how SSDs and hard drives in general work. Here, let me help.

        after using Seagate cheap stuff (SATA) and SCSI for years and never seen these things actually fail (besides stupid filesystems)

        Then you don't handle very many hard drives. I work in a data center and around 5% of the disks we buy fail within a few months. We don't have one brand in particular that we use because they seem to all fail at about the same rate. (Seagate does have the best warranty

    • Re:Still too new (Score:5, Interesting)

      by Gewalt (1200451) on Wednesday July 02, 2008 @11:35AM (#24031563)
      So what they are saying then is that this brand new technology is not as refined yet as the one that's been around for almost 30 years? Shocking!
    • by rolfwind (528248)

      I believe that much of the problem is that SSD's are still a new technology compared to rotating disks. Right now, engineers are more concerned with increasing capacity and just making the damn things work.

      Perhaps the problem is that rotating disks are too mature - I have not seen a capacity increase in a year and a half beyond 1TB (though I may have missed an announcement).

  • by Anonymous Coward on Wednesday July 02, 2008 @10:21AM (#24029937)

    I wish they would measure power usage under conditions that many notebook computer users actually use them in, which does not include running synthetic benchmarks on their computer 100% of the time it's running. Of course, if you keep the machine writing to the ssd constantly then it's not going to show power savings. But how many mobile users' usage patterns include constant reading from and writing to disk?

    • by Rakshasa Taisab (244699) on Wednesday July 02, 2008 @10:27AM (#24030053) Homepage

      Exactly... The thing about spinning platters is that it takes energy to start up _and_ keep it spinning. So obviously doing read/write 100% of the time would bias towards the conventional hard drives.

      Hell, even read/write 10% of the time is too much for normal usage.

      • Your correct also as a previous post pointed out here [slashdot.org] The CPU on a disk machine should be idle more. Count how many times the program ran in the time tested. If a program runs straight through to completion say twice as many times as the hard disk. Then it really isn't less efficient.
  • Sweet (Score:5, Funny)

    by Anonymous Coward on Wednesday July 02, 2008 @10:21AM (#24029943)

    Now I'm even happier that I paid the extra $1300 for the SSD option in my MacBook Air.

    That way it will run out of battery sooner, leaving me free to use a real computer.

  • by marc.andrysco (1173073) on Wednesday July 02, 2008 @10:22AM (#24029951) Homepage

    I believe this comment from the article could explain some of this away.

    'There could be a systematic error in the benchmarks shown: if the flash based "disks" are faster then the whole system CPU/MEM/Chipset would draw much more power with flash "disks" compared with conventional disks - just because the benchmarks could run more often in the same time.

    Maybe one should compare something like playing video from disk where it is assured that the systems do precisely the same work?'

    • by CastrTroy (595695) on Wednesday July 02, 2008 @10:26AM (#24030039) Homepage
      Not only that, but compare the power consumption when the disk is completely idle. Or at least when the computer isn't requesting any information from the disk. Most of the time, if your computer has enough RAM, it will access the drive quite infrequently, especially in many cases where power drain would be of concern, such as in those UMPCs.
      • by marc.andrysco (1173073) on Wednesday July 02, 2008 @10:34AM (#24030201) Homepage

        Yeah, another post mentioned that a SSD's power consumption during load is higher than another magnetic disk on idle... here it is:

        "The SanDisk SDD drive at LOAD requires 1.0 mW while Hitachi HDD requires 1.1 mW at IDLE"

        Of course, benchmarks are always a better indicator. Also, to be clear, as mentioned in the article (which I'm sure nobody else read), the test was performed by repeatedly running a benchmark on the system until it ran out of battery, so the test with the SSD is likely to have run the test more often.

        • I hate to be pedantic, but 1.0 mW is not higher than 1.1 mW ...

        • by peragrin (659227) on Wednesday July 02, 2008 @10:51AM (#24030553)

          Of course if the SSD is running under load the entire time it may actually run more often than a regular HD.

          from real world benchmarks SSD's only gain is from random reads. writes, sequential reads, etc all prove that SSD's are only as good as a regular spinning disk if not far worse.

          It is a trade off. both have advantages and disadvantages. Maybe in 5 more years SSD's will ultimately win but for now it can go either way.

        • Re: (Score:3, Insightful)

          If running the system until the battery failed was the measurement, well.. thats just stooopid. Who says the battery's lifespan is identical the second time? Where these tests done one right after the other? Because if the first test was run on a 'cool' battery and the second one run on a battery that was just finished recharging five minutes ago, there could be a large margin of error. Only using the internal power usage meter in watts could be even remotely accurate.
      • Re: (Score:2, Interesting)

        by drinkypoo (153816)

        if your computer has enough RAM, it will access the drive quite infrequently, especially in many cases where power drain would be of concern, such as in those UMPCs.

        ...which tend to have reduced memory.

        I really haven't found this to be true any more. My computer hits the disk pretty much all the time (for logging if nothing else) and I've got 2GB RAM. (Currently 1100M allocated in the user space - and all I'm doing is running my fancy desktop and firefox. Linux has truly reached parity with OSX... Firefox is using 128MB with a dozen extensions) And most windows users seem to have a ton of little system tray gadgets they think they need, as well.

        I do remember back when

        • if your computer has enough RAM, it will access the drive quite infrequently, especially in many cases where power drain would be of concern, such as in those UMPCs.

          ...which tend to have reduced memory.

          ...and which ship with operating systems designed to run in reduced memory. Puppy Linux, for instance, hits the disk less than Windows XP on the same PC.

          I really haven't found this to be true any more. My computer hits the disk pretty much all the time (for logging if nothing else)

          Then increase the buffering on the logs. You can get away with it on a laptop because a laptop has a built-in 2-hour-plus UPS.

          • by drinkypoo (153816)

            Then increase the buffering on the logs. You can get away with it on a laptop because a laptop has a built-in 2-hour-plus UPS.

            I would, but I'm running hardy-proposed, and I want to know why my computer crashed.

            Good idea, though.

        • by CastrTroy (595695) on Wednesday July 02, 2008 @10:52AM (#24030583) Homepage
          I think that as people request more power efficiency from their laptops, that we will be able to turn off logging, and any other unnecessary writing to the disk. I already boot up my laptop with the "noatime" option so that it doesn't cause an extra write to the disk every time I read a file. I think there's a lot we could do in order to cut down on the number of reads and writes we do. And since spin-up, and spin-down isn't a problem with SSD, we should definitely be trying to cut down on how much we use the drive.
        • by PReDiToR (687141)
          My EEE 4G has 4GB SSD, 512MB RAM.
          I'd like to think that it isn't suffering from reduced memory, it has the default Xandros distro on it which seems to be a fully fledged Linux system once you get it out of "easy mode".
          My other laptop (a tired old IBM T22) has 256MB in and runs openSUSE 11 quite happily.
          Is this "reduced memory" a Windows user term? I got Puppy Linux running on a Libretto that has 16MB RAM, and that I could probably say is a little on the small side.
      • Re: (Score:3, Interesting)

        Not only that, but compare the power consumption when the disk is completely idle. Or at least when the computer isn't requesting any information from the disk.

        Somebody correct me if I'm wrong, but isn't it true that with HDDs, the system can auto-power them down when they're idle, but with SSDs, this can't be done as easily due to the nature of SSDs?

      • by afidel (530433) on Wednesday July 02, 2008 @10:52AM (#24030587)
        Actually two out of four SSD's reviewed used MORE power when idle than the 7200rpm drive, that's just stupid. The Sandisk used about 60% less, so there's a reason to go with the name brand in this case, they do a heck of a lot more R&D than simply throwing some components together off the shelf.
    • by MBCook (132727) <foobarsoft@foobarsoft.com> on Wednesday July 02, 2008 @10:33AM (#24030189) Homepage

      That's an excellent point. I was wondering if the metric should simply be different altogether.

      What if we used MB/Watt or some such? The "disks" are supposed to be really good at some things (random reads) but don't hold too much advantage over others (long continuous reads). So how many WattHours does it take to load a continuous 50 GB file? How about a random 50 GB of data off a 128 GB disk? How does that compare to the same measurements with a standard magnetic disk? How does power consumption change between reading, writing, and mixed disk loads? Writing flash takes far more power than reading, doesn't it? Yet on a physical disk it's not that different in power requirements.

      There are other things too. Operating systems still aren't designed around these things, they are designed for physical rotating disks. Do these things even have native controllers (designed for this purpose) yet, or are they still using modified rotating disk controllers like the first models used? As time goes on, better power saving features will show up, especially as the OS cooperates to tell this disk more information about what's going on. A well managed flash drive may be able to shut off large chunks of it's self and only wake up the bits that actually need reading/writing. That would help quite a bit, I'm sure.

      PS: First time I've been to Tom's Hardware in 6 months to a year. Nice to see they found a way to make it uglier. Used to be a nice site. I especially like the "you must login to see the printer friendly version" trick.

      • Re: (Score:3, Interesting)

        by b0bby (201198)

        PS: First time I've been to Tom's Hardware in 6 months to a year. Nice to see they found a way to make it uglier. Used to be a nice site. I especially like the "you must login to see the printer friendly version" trick.

        I don't go there at all anymore; I've got my ipcop box running URL Filter with the Squidguard blacklist, and whatever tracking junk they run at Tom's just leaves me hanging with a 1x1 gif. It's not even worth my while to add them to the whitelist.

      • A well managed flash drive may be able to shut off large chunks of it's self and only wake up the bits that actually need reading/writing. That would help quite a bit, I'm sure.

        A very reasonable idea. A friend of mine who happens to be working on Linux power saving features once noticed [mff.cuni.cz] that the disk controller of X60 in fact consumes even more then an idle disk - at least if I understand it correctly. As the flash does not need to spin up, if you can wake up the controller quickly enough and turn it off a

      • Re: (Score:3, Interesting)

        by Eil (82413)

        Operating systems still aren't designed around these things, they are designed for physical rotating disks.

        How exactly are current OSes designed for physical rotating disks?

        You wouldn't design an OS around the hard disk any more than you would design one around the keyboard or power supply. As far as any OS is concerned, /dev/sda is just a block device, no matter whether it's a single-spindle hard disk, solid state disk, or a 42-disk hardware RAID 5. If the SSD needs any special treatment (such as wear-leve

    • Re: (Score:2, Insightful)

      by PacketShaper (917017)
      Not sure why this has not been mentioned already, but it seems the whole experiment is flawed.

      Why would they measure whole-system power draw to test the disk power draw? Why not simply put a power meter in-line with the power connector of the HDD?
  • I would use one of these SSDs on a Desktop Computer or a Server, because in those two situations I am looking for performance, rather than portability that I would want in a laptop.
  • by Plammox (717738) on Wednesday July 02, 2008 @10:24AM (#24030007)
    ...it's like LCD TVs, people also thought they consumed less power than conventional CRTs. Personally, I can warm my hands if I stick the palms up in front of my 32" LCD which chugs away at 152W when fully "lit" (powersave mode off).

    A 32" Philips HD ready CRT was around 100-110 W at the time I looked.
    However, this is highly dependent on brand as well.
    • by afidel (530433)
      Wow, that seems really inefficient, my 42" is only 169W max (typical is more like 110W). I can't find the power usage numbers for what I believe is the only 42" CRT produced, the Mitsubishi MegaView Pro 42, but it weighs in at 200lbs!
    • Hm. I didn't believe you at first, but it does appear to be true that big LCD panels are hideously inefficient.

      Although a 19" LCD will easily draw far less power than a 19" CRT (about 1/3), the same doesn't appear to hold true for big TVs.

      Does anybody know why this is? It seems extremely counterintuitive.

    • Re: (Score:2, Informative)

      by GleeBot (1301227)

      ...it's like LCD TVs, people also thought they consumed less power than conventional CRTs. Personally, I can warm my hands if I stick the palms up in front of my 32" LCD which chugs away at 152W when fully "lit" (powersave mode off).

      Conservation of energy still applies here. It's not that LCD technology is necessarily less efficient (compare a scanning electron beam exciting phosphors to cold cathode fluorescent), it's that people have demanded (and gotten) much brighter screens, sometimes by a factor of 5-10 or more.

      Obviously, if you're putting more light out of the screen, you're going to need to pull more energy out of the wall. There's no free lunch. If you care about saving power, turn down the brightness. Otherwise, don't sw

  • by jonnythan (79727) on Wednesday July 02, 2008 @10:26AM (#24030047) Homepage

    The thing is that Tom measured battery life with the hard drives constantly working.

    He glosses over this with the following statement:

    Keep in mind that this benchmark keeps the system busy in several disciplines, and the results would of course be different if we measured the runtime in idle. However, this wouldnâ(TM)t quite reflect user behavior, as no one turns the notebook on just to wait around until the battery runs empty.

    No, Tom, no one turns on their computer and simply waits for the battery to die. However, no one turns on their computer and has their hard drive constantly thrashing either.

    Typical usage patterns include document editing, movie watching, music listening, etc, which involve very, very small amounts of hard drive access.

    Use a better battery benchmark that leaves the hard drive idle most of the time, then come back and let us know how these drives fare.

    • Re: (Score:2, Informative)

      by Anonymous Coward

      Tom = Patrick Schmid and Achim Roos

    • Swap (Score:2, Insightful)

      by zippthorne (748122)

      Why are we still using swap? We can put, cheaply, more than 4 gigs of ram in a machine. With the differences in SSD, and the concerns about power efficiency, it really makes no sense to me that machines are still being designed to page out memory.

      • Re:Swap (Score:5, Interesting)

        by SDF-7 (556604) on Wednesday July 02, 2008 @10:50AM (#24030535)

        Because in general folks know how to do it (so you're not adding code complexity in most cases) -- and it seamlessly handles the odd folks who *do* eat all of their RAM in a workload and end up needing it. (And since the folks with big working sets relatively to current states also tend to be the folks paying more money... they do get listened to -- and these are the same folks that would require a perfect patch in 24 hours when they're unhappy, so you're much better off having a little planning pre-release than trying to crowbar this in post).

        The thing to do is to make the virtual memory subsystem as efficient as possible about handling swap statistics just in case you need it so that the folks who really don't need it aren't aggressively impacted.

        (Note: I am a virtual memory subsystem kernel engineer -- but not on Windows. I make no claim about how efficient or inefficient Windows is at doing this as a result. I would seriously expect that since they're designing the core kernel to operate from laptops up through Windows Server Whatever --
        they have to accommodate cases beyond the 4Gb in your laptop should be enough to keep everything in core, though. )

        • Re: (Score:3, Interesting)

          by Ilgaz (86384)

          Used/tried a Quad G5 with 16 gig memory installed (mine has 4,5 GB).

          Even on Leopard, that mainframe like monster will still create a 64MB swap file amusing us. I also saw 6 swapfiles has been created on my 4,5 GB RAM installed Tiger (OS X 10.4, doesn't have auto cleaning) after days of heavy load uptime.

          Is it a strategic thing that OS kernel does? I remember reading some real weird stuff about Microsoft's tactic to swap the applications to disk even while they didn't have to but I can't find the file now. Y

          • Re: (Score:2, Informative)

            swapping is often done on a modern system in order to increase performance by increasing cache space. By swapping out applications that are almost never being used, like say, the quicktime tray or something, there is more ram available to cache program data for applications that you are using much more heavily.
          • Is it a strategic thing that OS kernel does? I remember reading some real weird stuff about Microsoft's tactic to swap the applications to disk even while they didn't have to but I can't find the file now.

            No matter what amount of memory you have, it might be often more useful to swap out the application you have not touched for the last two hours and use the memory pages for the disk cache instead so that the apps you are using right now do not have to hit the disk constantly. It is quite possible that on

          • by SDF-7 (556604)

            Most Enterprise-class Unix OSs by default want swap "just in case". The defaults are that each new virtual object created (malloc / anon mmap, etc.) reserves the equivalent amount of swap so that if the system ever does get under pressure -- the OS will have to figure out what disk block/FS range/whatever it will use to page the memory object, but it will be guaranteed that it will find the appropriate resources available. As such - the OS is unlikely to ever really need that actual disk space (the performa

      • Re: (Score:3, Informative)

        by peragrin (659227)

        well In linux and OS X you can actually disable swap. Windows however relies on it heavily, and with Vista under 4 gigs of ram you need swap space to store the entire OS.

      • Re: (Score:3, Insightful)

        by afidel (530433)
        All those chips for RAM require power too...
    • by neokushan (932374) on Wednesday July 02, 2008 @10:40AM (#24030337)

      I think the article is still somewhat Valid, though, even if it does gloss over some of the details a bit.
      The short end of it is that a SSD will use less power when idle, but more power at full load than a typical hard drive will, which may be a real factor when deciding which to purchase.

      Personally, though, I don't see the real benefits to them in 99% of situations. Their performance is only marginally better than standard HDD's and, as you pointed out, MOST people wont regularly thrash the HDD anyway. Plus, they're expensive - you could spend a little extra on a bigger and/or additional batter and some more RAM, get a massive regular hard drive and probably still come to less than half the price of a 32Gb SSD.

      Hopefully when the technology matures a bit, they'll be to HDD's what the common DVD was to CD's.

      • by initdeep (1073290)

        funny
        i bought my Dell xps m1330 with 3gb of ram, 64gb SSD and all of the other bells and whistles available at the time for lessthan $2k.

        doesn't seem all that expensive to me.

      • by TheRaven64 (641858) on Wednesday July 02, 2008 @10:56AM (#24030665) Journal
        It's not that SSDs use less power when idle, it's that they can transition between idle and non-idle modes much more quickly. Spinning up a hard disk takes several seconds and uses more power than leaving it spinning. Turning an SSD on is just a matter of putting power into the flash chips. This means that you can turn of an SSD as soon as you stop writing, while a mechanical disk can only be powered down when it's not likely to be used for a few minutes or more (and, even then, degrades the user experience by making them wait for it to spin up again). If you are hitting the disk for a second once every ten seconds, then an SSD needs power for six seconds per minute, while a hard disk needs power for 60 seconds per minute. Looking at the disk activity graph on my laptop, this is about the usage pattern that I see most of the time.
        • I was wondering why these SSDs draw any power at all while idling - I guess they have to leave the controller powered up, but some of the figures quoted were around 2W when idle - you can get x86 processors that run on less than that FFS!

    • by DFJA (680282)
      >However, no one turns on their computer and has their hard drive constantly thrashing either.

      Yes they do- they're known as Vista users.

    • by Lumpy (12016)

      However, no one turns on their computer and has their hard drive constantly thrashing either.

      you haven't seen a 4 year old windows machine boot have you. Last one I fixed for a client the hard drive thrashed for 1 hour after boot and NOTHING was touched. There was so much spyware and other crap loading it was insane.

      and that seems to be the norm for most consumers PC's... full of crap and constant disk thrashing for most of the time.

      • by Thaelon (250687)

        That has nothing to do with the age of the machine or the operating system on it.

        I have a windows XP machine at home that was up to 60 days of up time before the power went out. No perceivable slowdown in any application.

        I would liken your example to running a car for four years and never changing the oil or other fluids, then complaining when it doesn't run well.

        And one hour boot times are NOT the norm. At that point most uneducated users will think it's "worn out" and simply go buy a new one. Of course

  • Author = Clueless (Score:5, Insightful)

    by Rhys (96510) on Wednesday July 02, 2008 @10:32AM (#24030165) Homepage

    He makes the claim in the comments about the article that "well who just watches dvds? You have to keep the system busy and test that!" That's about as valid as setting the machine not to sleep and seeing how long it can idle there.

    On an ultraportable especially, you aren't going to be churning the CPU with a benchmarking program. You won't be rendering animation frames. Mostly you'll be in a web browser or text processing program, waiting on the user to type something. With occasional spurts of OS and program start/stop. Good gosh it sounds like a MIX of tasks, rather than either extreme.

    • Re:Author = Clueless (Score:4, Informative)

      by Chrononium (925164) on Wednesday July 02, 2008 @01:33PM (#24033583)

      At Apple (a few years ago), we would test typical portable battery life by scripting a set of tasks for the computer, both in OS X and in Windows. This way, we would be trying to simulate this common mix of tasks and obtain more realistic battery lifetimes (and comparison between similar Windows laptops and our own). Naturally, it wasn't always the case that our benchmarks were the ones put up on the web.

      Stuff like this benchmark is really just an extreme corner case. As an engineer who relies on lots of hardware to help perform long and complex simulations, I know something about thrashing a system to death. And yet, I would never, ever, ever run such a continuous thrasher on my laptop (at least without plugging it into the wall). Their scenario seems (to me) as extremely unrealistic and may qualify as FUD.

  • by slaker (53818) on Wednesday July 02, 2008 @10:41AM (#24030343)

    I have a 32GB SSD in my T61. My real life usage shows that I get between 30 and 45 more minutes of battery life out of my SSD-equipped notebook than on my other T61, which has a 160GB 7200rpm drive in it, when both of them are on the "medium" power saving setting in Windows.

  • Am I the only one... (Score:5, Interesting)

    by initdeep (1073290) on Wednesday July 02, 2008 @10:48AM (#24030497)

    Who thinks that maybe the overall bettery life would be more affected by the HEAT the laptop is putting out?

    After all, most laptops I've ever dealt with or owned are compact little furnaces that have their hard drives, cpu, gpu, and everything else shoved in as little space as possible in order to make room for things like batteries and keyboards.....

    thus if they remove a high heat generating device (even more so with a 7200rpm drive) wouldn't logic also assume that you reduce the amount of heat needing to be removed from the system?

    thus the fans would run less often, and therefore drain less battery power.
    not too mention the proposed savings by simply accomplishing tasks "faster" when it comes to disk access.

    • by MozeeToby (1163751) on Wednesday July 02, 2008 @10:59AM (#24030747)

      Well, since power usage is directly related to heat output, we could benchmark SSD's versus standar drives much more scientifically; we could even use the author's broken benchmarking tool. Put the hard drive into a calorimeter, run the benchmark for 10 minutes and measure the total heat output. Repeat for the drive you are benchmarking against and presto, actual, scientific numbers on power usage for just that device, rather than simply plugging away until the battery runs dry.

    • by compro01 (777531)

      For the most part, power use = heat dissipation. Practically all the power that is used is lost as heat (with a little going towards light).

  • by Endo13 (1000782)

    And here I've been, thinking all this time that the real benefit to SSDs was that your laptop could fall off a table while running without killing the hard drive. Silly me.

    • by Ilgaz (86384)

      If you have Macbook Air and I don't recommend trying it, you would be amused to figure it still cares about sudden motion sensor blocking the access to SSD drive when it falls.

      I have read about it on a Developer's blog who has been really surprised. It could be Apple's philosophy to ship the exact same OS X on every machine, there is a plist tweak to disable the sudden motion sensor.

  • by SDF-7 (556604) on Wednesday July 02, 2008 @10:54AM (#24030625)

    Seems unlikely to be all that power efficient to me... hauling around that huge bulk, and it sure didn't seem like Executor really made all that difference at the Battle of Endor from a capital ship perspective. (Probably because most turbolaser batteries seem to have really lousy guidance,
    after all).

    Oh... you meant those SSDs.... my bad.

    • by dkf (304284)

      To the person who modded the parent Informative, I salute you on behalf of Slashdot!

    • (Probably because most turbolaser batteries seem to have really lousy guidance, after all).

      Hey! YOU try shooting down a mosquito with a .50 caliber machine gun some time and let me know how it goes. Who could have predicted the pesky rebels would resort to using FIGHTERS?!

  • Old and inaccurate (Score:5, Informative)

    by jlp2097 (223651) on Wednesday July 02, 2008 @11:04AM (#24030867) Homepage Journal

    The article states nothing new - there are two very interesting blogs from Lenovo which already stated the same in August 07 (!). To quote:

    Solid state HDDs promise to save power compared to traditional hard disk technology. And they will. However today's generation of SSDs have no power savings benefit compared to traditional HDDs. The big reason is that current SSDs with a Serial ATA interface are actually Parallel ATA hard disk drives with a serial bridge chip. They don't offer support for low power interface states and the architecture has a potential for data-losing error conditions when recovering from a low power state like suspend or hibernate. In the future, there will be native SATA solutions which will solve many of these problems and will at the same time offer a real power savings benefit which should increase battery life.[1]

    An updated quote from a newer blog:

    Power Consumption - All SSDs are going to save you battery life on your notebook, but some will save you more than others. Again, the native SATA drives will give you better battery life.[2]

    To summarise: old news and mostly outdated with very recent SSD drives.

    [1]: SSD part 1 (Aug 07) [lenovoblogs.com]

    [2]: SSD part 2 (March 08) [lenovoblogs.com]

  • Check Page 14 (Score:5, Insightful)

    by pjrc (134994) <paul@pjrc.com> on Wednesday July 02, 2008 @11:22AM (#24031293) Homepage Journal

    In TFA, there is a graph on page 14 with power consumption measurements for the 5 drives tested.

    The SanDisk SSD shows 1.0 watt active, 0.5 watt idle.

    The Hitachi drive (magnetic) shows 3.2 watts active, 1.1 watts idle.

    So even if the SanDisk drive spent 100% of its time in active mode and the Hitachi drive was always idle, the SanDisk drive should still provide longer runtime.

    However, their runtime test (page 12) shows 7:03 runtime with Hitachi, 7:02 with the SanDisk.

    All they have to say about this is:

    Most of the power consumption measurements are in line with our results in Mobilemark 07. However, it has become clear that idle and maximum power do not provide the full picture when we talk about flash SSDs.

    Well, something clearly is wrong here.

    • by Rhys (96510)

      Idle cycles while waiting on the physical HD to do something = power savings due to speedstep/descendants of it.

      No big mystery, just an author measuring something that's useless and irrelevant to make a splash.

  • SSD's are like 8 frickin' times longer than ISD's, of course they'd be more powerful.

  • iPod counterexample (Score:3, Informative)

    by sunderland56 (621843) on Wednesday July 02, 2008 @11:24AM (#24031327)
    The battery life of a flash-based iPod nano is basically identical to that of a HD-based iPod Classic. However - the battery in a Classic is much larger.

    Obviously the use model for both devices is the same.
  • Already debunked.... (Score:4, Informative)

    by Junta (36770) on Wednesday July 02, 2008 @11:57AM (#24032017)

    The testing methodology was flawed to draw any conclusions. The problem is the CPU may have been more active due to less IOWait states. AS a resulte, the drive consumption may be lower, and the benchmark was not throttled to the platter disk performance. The benchmark might have run many more times during the test.

  • by John Jamieson (890438) on Wednesday July 02, 2008 @11:58AM (#24032031)

    The title "Some SSD devices are inefficient" just does not drive page clicks. So Tom sensationalizes some facts, omits others, runs questionable synthetic benches and Voila... Slashdot delivers the page hits.

    Tom sometimes takes known "problems" and dramatizes them. After all, an objective view should not be allowed to stand in the way of revenue generation.

    As others have pointed out.
    1. The reason for inefficient drives was usually power hungry interface logic chips.
    2. The newer drives are all better according to a Lenovo blog (thanks jlp2097)

    And to top it off the numbers don't even add up (see PJRC's nice post above).

  • by Anonymous Coward

    Intel rolled out a 100+ person pilot program of it's currently sampling SSD. Users noticed a giant increase in productivity for HD-limited activities and significant battery life increases (25%+).

    While the data from the experiment is valid, it's not reflective of a client workload, where a user produces x spreadsheets and y emails in a typical day. Under the experiment performed, you're performing a poor-man's version of a enterprise workload, where the results are well known -- SSDs won't save power pe

  • Seems like many of the objections can be roughly translated as: "If Bob can toss 60 shovels of dirt a minute and Ray can only toss 50, and both walk out in the same field and each dig a ditch for an hour ... " Tom's site asked "which one consumed more calories?" Instead of "which one moved more dirt?" Either is a valid measurement to take. What I take away from the article is not "OMG they LIED" or even "OMG Tom LIED". Instead, it is that different SSD's have widely varying performance and power profi

A bug in the code is worth two in the documentation.

Working...