Sign in with
Sign up | Sign in
Your question

Real vs Advertsied HD Capacity - The "7% Rule" ??

Last response: in Storage
Share
August 3, 2007 3:32:52 AM


I understand the basic concept here that HD capacity will never be quite what the manufacturer claims, since HD manufacturers like to think that 1 MB = 1,000,000 Bytes, while computers know the truth, that 1 MB = 1,048,576 Bytes. Plus, when formatting, some space will be lost to file system overhead.

What I'm unclear on is exactly how much total space should be lost. So far, the largest drive I've had is a 40 GB, so the file space loss as been minimal. Now that I'm looking at 320 GB and 500 GB drives for my new build, I'm seeing many people on New Egg complain about lost file space, and wondering if these loses are drive errors or completely normal.

What's caught my eye so far:
  • A 320 GB Drive with 298 GB of actual storage
  • A 500 GB Drive with 465 GB of actual storage


  • At first, not being used to large hard drives, I thought something was wrong here. Now, I'm starting to think these numbers are exactly what they should be. One New Egg user pointed out that you should expect to lose 7% to the math issue and file system overhead, which is what was lost in both of the above examples.

    I'd appreciate some comments from the forum's readers as to whether those numbers look like defective hard drives, or exactly what should be expected.

    Thanks
    August 3, 2007 4:04:37 AM



    As you can see, those numbers are on the dot. They are not defective drives.
    August 3, 2007 4:28:22 AM

    AARRGGHHH said:

    I'd appreciate some comments from the forum's readers as to whether those numbers look like defective hard drives, or exactly what should be expected.

    Thanks


    Those numbers are right on. I do wish that hard drives were advertised refering to their real, usable space, though. As the drives get ever larger, the difference between advertised size and usable size become considerable, and I for one consider the present advertising to be false advertising. If I buy a drive with 500 GB, I want a drive that has 500 GB for me to use. Alas, the companies don't care what I think, so I'm stuck for it.
    Related resources
    August 3, 2007 4:58:13 AM

    Technically the drive makers are correct according to international standards. a 500GB drive is 500 billion decimal bytes. While what you wish to see is 500GiB which is 500 in binary. Unless they advertise the drive in GiB's it is not false advertising. GB (gigabyte) is 10 to the 9th power while GiB (gibibyte) is 2 to the 30th power.

    The next increment that is upon us is TB (terabyte) 10 to the 12th power versus TiB (tebibyte) which is 2 to the 40th power. What has confused the issue is RAM makers who have always given us what we expect and still use the technically incorrect MB and GB designations. However look how long it has taken to start to kill IDE and EIDE when many knew all along that it should have been ATA. So now we see PATA and many are even more confused thinking it is some new technology that slipped by them. :sleep: 
    August 3, 2007 6:12:37 AM

    Quote:
    a 500GB drive is 500 billion decimal bytes. While what you wish to see is 500GiB which is 500 in binary. Unless they advertise the drive in GiB's it is not false advertising. GB (gigabyte) is 10 to the 9th power while GiB (gibibyte) is 2 to the 30th power.


    Mr. azimuth40, i don't know if yout statement is true or not, as this is the first time I've those terms. However, I'm not sure if you are stating that this is the reason for the confusion in avaiable drive space or not. I was under the impression that a percentage was just used for system overhead.


    ??
    August 3, 2007 10:08:07 AM

    for more info i have a 320gb hdd and i get 305gb. Not a big Prob
    August 3, 2007 11:23:43 AM

    azimuth40 is spot-on. 1000 / 1024 is 0.9765625. Multiply that by itself 3 times (for Giga vs. Gibi; 2 times for Megabytes, and 4 times for Terabytes), and that's the portion of the marketed drive space (in gigabytes) that Windows will report (in gibibytes). Because Windows reports in Gibibytes, and drive marketers report Gigabytes. Sailer's complaint is probably better worded as, "I wish advertisers used the same units as [his preferred file browser]". As long as you're willing to do the math, you can predict precisely how much space you'll see on your new drive. And none of it is "lost", just as when a car driving at 100 kph hasn't "lost" any speed when you see the speedometer reporting 62 mph.
    August 3, 2007 12:22:57 PM

    azimuth40 and TeraMedia are correct. There is nowhere near a 7% file system overhead. It's minimal. The "loss" comes from the conversion from decimal byte counts to binary byte counts, which coincidentally for those of you who someone did not know this, is what computers understand natively! I know, hard concept.

    Most posters on Newegg are idiots. I can't stand to see what they say about hard drives because it's so moronic. "omg i lost 35gb dont buy this drive im rmaing it today i hate ___ company they suck!"

    What is interesting is that this reporting by advertisers of drive capacity in decimal bytes seems to be unique to PATA, and now SATA drives. In the SCSI world, you almost universally see the size reported in decimal bytes. The 160GB drive becomes a 147GiB drive. And the buyers then know exactly what they will get.

    August 3, 2007 1:25:40 PM

    AARRGGHHH said:
    At first, not being used to large hard drives, I thought something was wrong here. Now, I'm starting to think these numbers are exactly what they should be. One New Egg user pointed out that you should expect to lose 7% to the math issue and file system overhead, which is what was lost in both of the above examples.

    I'd appreciate some comments from the forum's readers as to whether those numbers look like defective hard drives, or exactly what should be expected.

    Thanks


    numbers are right, and it gets even better!
    common storage practices tell you to leave 20% of your drive empty for effective use. meaning defragmentation, keeping things running smoothly, other possible isues like bad clusters and such. you dont really want to go under 20% free on a drive for long periods of time.

    so if you go by that, yes, you have 500 gig in the marketing letters on the box, you have 465 gig of actual space, and you have 372 gig of USEABLE space.

    math is fun.

    Valis
    August 3, 2007 2:37:27 PM

    TeraMedia said:
    azimuth40 is spot-on. 1000 / 1024 is 0.9765625. Multiply that by itself 3 times (for Giga vs. Gibi; 2 times for Megabytes, and 4 times for Terabytes), and that's the portion of the marketed drive space (in gigabytes) that Windows will report (in gibibytes). Because Windows reports in Gibibytes, and drive marketers report Gigabytes. Sailer's complaint is probably better worded as, "I wish advertisers used the same units as [his preferred file browser]". As long as you're willing to do the math, you can predict precisely how much space you'll see on your new drive. And none of it is "lost", just as when a car driving at 100 kph hasn't "lost" any speed when you see the speedometer reporting 62 mph.


    Having worked with computers since 1970, I do understand the technicalities of the subject. Better or different wording what I wrote may also make more sense. Don't know about that. I also realize nothing is lost, it just doesn't read the same in the files as it does on the box. What I was trying to say was that I would like to see the advertised space on the box as being the same that is shown when I open "My Computer" and look at the drive sizes and available room for use.

    @Valis I still remember the time that I had a drive 98% full and I couldn't understand why it was so slow. Defragging didn't help, nothing seemed to work correctly. Then I learned. I know the facts of it all, but it somehow is a bit deceptive when a hard drive company to sell a 500 gb disc that has only about 372 gb of useable space, a little over 2/3rds the advertised space. A possible way of comparison would be if you went to buy a 12 oz can of beer and found there was only 8 1/2 oz in the can that you could actually drink, the rest being sealed away for various reasons.

    @ azimuth40- I think the ram manufactorers got it right. They labeled the ram as the amount that we get to use. I'd like to see the hard drive manufactorers doing the same. Maybe the ram labeling is technically incorrect about how much is there, but it tells me at a glance how much I have to work with without going through mathmatical formulas, loss to overhead, etc. Ok, I don't really except any hard drive company to relabel the drive to fit my wishes. But maybe a secondary label so that the box would read "500 gb Drive, 372 gb of useable space". Ok, enough of my useless rant. Its not about to happen and I know it.
    August 3, 2007 3:59:01 PM

    azimuth40 said:
    Technically the drive makers are correct according to international standards. a 500GB drive is 500 billion decimal bytes. While what you wish to see is 500GiB which is 500 in binary. Unless they advertise the drive in GiB's it is not false advertising. GB (gigabyte) is 10 to the 9th power while GiB (gibibyte) is 2 to the 30th power.

    The next increment that is upon us is TB (terabyte) 10 to the 12th power versus TiB (tebibyte) which is 2 to the 40th power. What has confused the issue is RAM makers who have always given us what we expect and still use the technically incorrect MB and GB designations. However look how long it has taken to start to kill IDE and EIDE when many knew all along that it should have been ATA. So now we see PATA and many are even more confused thinking it is some new technology that slipped by them. :sleep: 


    While the rest of the SI system uses even base 10 numbers, it really doesn't make sense to use them in the binary world of computers. Sure using a base 10 system in everything else makes a lot of sense because we are using a base 10 numbering system as well. But to try and use a base 10 numbering system on a base 2 system doesn't make sense at all. I mean if you are going to use names that don't actually corrispond to anything then you may as well take everything back to the imperial system where unit names change on whatever value comes to mind at the time.

    I'm not sure how long HD manufacturers have been doing this, probably a long time, but I don't remember noticing it until they started to go to GB, but that may just be because the numbers started getting bigger.

    I'm sure it was just some guy in markettings that saw all the numbers and didn't know what they actually ment so they decided 1GB sounded better then the real 930MB they had and other manufactuerers followed suite because they knew the consumer didn't know any better and would think the bigger number actually said something.

    As a side note my raptor 80GB drive was both sold as, and runs as the actual 74.4GB that it really is.
    August 3, 2007 4:40:32 PM

    erloas said:

    As a side note my raptor 80GB drive was both sold as, and runs as the actual 74.4GB that it really is.


    And that is exactly that type of thing that I like.
    August 3, 2007 4:55:44 PM


    Many thanks to f1nal_0men, Sailer, and many others, for confirming my suspicion that both the 500GB (aka 465GB) and 320GB (aka 298GB) drives were both functioning normally.

    Quote:
    Most posters on Newegg are idiots.

    lmao - Unfortunately, there is a great deal of truth to that.

    I always look at the review numbers and read some reviews when I buy a product there, but I take it with the proverbial grain of salt.

    If I know from experience that a particular company has a history of manufacturing crap, or alternatively, has a history of delivering everything I expect and then some, that carries far greater weight than a review from someone who's only known credential is having an internet connection.
    August 3, 2007 6:04:35 PM

    I take a spoon full of salt when it comes to newegg's reviews.
    August 3, 2007 6:12:28 PM

    Heyyou27 said:
    I take a spoon full of salt when it comes to newegg's reviews.


    Just a note to add on the Newegg reviews. I look at them and try to find out what a common complaint is. For instance, I bought a new sound card last week. It received a lot of complaints, but the complaints were centered on how many difficulties it had with Vista. Since it was going into an XP machine, I separated those complaints out and looked at the reviews of its performance with XP. Then it scored much higher on the numbers of "eggs" awarded. I then bought it with a degree of confidence that it would work with my computer.
    a b G Storage
    August 3, 2007 7:04:49 PM

    The easiest way for me to calculate the actual space is by using the following equation:

    [HDD SIZE]x10^9 divided by 1024^3

    500 = 465.7
    400 = 372.5
    320 = 298.0
    250 = 232.8
    200 = 186.3
    160 = 149.0 etc...

    It's funny, you never hear people bitching about RAM. "I thought this came with 2 Gig of RAM, but Windows says I have 2048MB!! Where'd that extra 48MB come from???!!!" :lol: 

    No one ever questions the 1024mb = 1 gig in that case :sarcastic: 


    August 3, 2007 11:30:57 PM

    erloas said:
    As a side note my raptor 80GB drive was both sold as, and runs as the actual 74.4GB that it really is.


    No, the Raptor is sold as a 74GB drive. That's 74,000,000,000 bytes. Windows reports the drive size as 68.92GB. Both are correct, depending on how "GB" is defined, as has already been discussed.

    The key thing that everyone needs to keep in mind in order to keep everything straight is to never count things in terms of KB, MB, GB, TB (or KiB, MiB, GiB, or TiB). Talk about the size of the drive (and your files, for that matter) in terms of bytes, and everything will make perfect sense.

    Example: You buy a Raptor. You get 74,000,000,000 (74 billion) bytes. Period, end of story, no confusion. 74 billion is concrete and exact, no matter if you're the hard drive manufacturer, the OS manufacturer, or the man in the moon.

    The difference between GB based on powers of 10 (HD manufacturer use) and GB (really GiB) based on powers of 2 (OS manufacturer use) is just a difference in labelling. It doesn't matter if one labels it 74GB and one labels it 68.9GB. They're talking about the same number of bytes ... 74,000,000,000. Thus there is no missing space.

    It's just like if you purchase 4 quarts of gasoline. It doesn't matter if you call it 4 quarts or 3.78 liters. You're talking about the same amount of fuel.
    August 4, 2007 3:28:21 AM

    rwpritchett said:

    The easiest way for me to calculate the actual space is by using the following equation:

    [HDD SIZE]x10^9 divided by 1024^3

    500 = 465.7
    400 = 372.5
    320 = 298.0
    250 = 232.8
    200 = 186.3
    160 = 149.0 etc...


    Seems then that "The 7% Rule" that one of the more knowledgeable people on New Egg mentioned is pretty accurate, at least as a rough guide:

    500 * .93 = 465
    400 * .93 = 372
    320 * .93 = 297.6
    250 * .93 = 232.5

    etc...
    August 4, 2007 4:20:36 AM

    mundungus said:
    Quote:
    a 500GB drive is 500 billion decimal bytes. While what you wish to see is 500GiB which is 500 in binary. Unless they advertise the drive in GiB's it is not false advertising. GB (gigabyte) is 10 to the 9th power while GiB (gibibyte) is 2 to the 30th power.


    Mr. azimuth40, i don't know if yout statement is true or not, as this is the first time I've those terms. However, I'm not sure if you are stating that this is the reason for the confusion in avaiable drive space or not. I was under the impression that a percentage was just used for system overhead.


    ??


    Sorry they are an addition to the engineering measurement standards "SI" as erloas pointed out. Proposed by the IEC and jointly recommended by NIST and ISO you can find a definition on the US NIST web site here http://physics.nist.gov/cuu/Units/binary.html . It also points out that IEEE can take some of the blame although they had good reasons for walking us all down this confusing path. It is a nice page to book mark when someone else asks you this question. Like sailor I started in this business in 1970 with Burroughs corp, now Unisys, on large Algol systems so I never give the conversions much thought having been there, done that and got the stupid tee shirt. Therefore I often forget that is is still a problem for those fairly new (by my standards ) to the field. If you right click on the drive icon and go to properties (the pie graph) you will see the true decimal value which should closely match the box identification. My two internal Seagates are listed as 500,105,736,192. My external USB Seagate Freeagent is listed as 500,015,216,000. Hey they stole over 500K i'm going to send it back Nah but on my original 10meg XT that would have been a lot of space to lose.

    The ram makers can be excused because there in no really efficient way to design storage cells using decimal; binary is just a natural for all things computer related. Internal to a disk drive it is all binary also, so basically this is slick marketing hype. If you look in your BIOS you will still see odd ball drive numbers that are a direct result of past drives being defined correctly before the marketing people got another one of their great ideas.

    August 4, 2007 4:58:02 AM

    The only people that get pissed off about the HD size are those that don't know better. As was stated a few times in this thread this is not a new problem. There is no conspiracy. All of the drive manufacturers have to compete on the same playing field. Is the difference going to really hurt that bad? I hope not because that means that you didn't buy a large enough drive. I am setting up a computer and I was going to use a WD500GB drive for $100. Damn cheap if you ask me. I instead decided to buy a 150GB Raptor for double the price. Now that is getting robbed, and no better way to be fleeced. All I'm saying is stop complaining. If this was the worst thing in my life I would be dancing in the streets.
    August 5, 2007 6:55:59 PM

    then there is one thing that if windows take 7% or so, then y does the op's 320gb seagate hdd shows 298gb, while my seagate hdd which is 320gb shows 305gb? assuming we both use win XP. if we both use XP then y is there any difference in figures?
    a c 342 G Storage
    August 9, 2007 10:06:39 PM

    Don't blame the HDD makers, blame the early computer nerds and Microsoft's choices. The denizens of digital worlds decided to re-define the decimal world prefix "kilo" as 1024 instead of 1000. So "Mega" is 1024 of those, and Giga is 1024 of those. Thus a "gigabyte" in that view is 1024^3 or 1,073,824 bytes. And if the HDD maker says their unit provides 320 GB, meaning 320,000,000,000 bytes of space, Microsoft divides that by the convesion factor above, which is the same as muliplying by 0.931322575 x 10^-9. You get 298.02 Gigabytes in the nerd's version of "Giga". Note that conversion muliplier is 6.86775% less than 1. "7%" - aw, close enough!

    We might note that the 1024 factor is 2.4% off of 1000. But when it is used on itself a total of three times, as in 1024^3, the % difference is three times the original, or about 7%. And when we do it again in "Tera", the difference will become a bit more than 9%.
    August 10, 2007 2:22:09 AM

    sailer said:
    Having worked with computers since 1970, I do understand the technicalities of the subject. Better or different wording what I wrote may also make more sense. Don't know about that. I also realize nothing is lost, it just doesn't read the same in the files as it does on the box. What I was trying to say was that I would like to see the advertised space on the box as being the same that is shown when I open "My Computer" and look at the drive sizes and available room for use.


    Well, my file browsers reports drive space in Gigabytes, not Gigibytes, so I see my 500GB drive as actually having 500GB. And my friend Joe has his file browser set to some weird base nine counting scheme, so sees 372.38364826492746392804634928439742072469347034... GB through his file browser.

    See how that works? The problem isn't the number on your box, it's the number in your file browser. MS has never been able to adhere to standards (even the ones they write :ange: ), so I'd really hate to see HD manufacturers start using improper standards to conform to some made up MS standard that it'll probably do away with in SP3 anyway.
    August 10, 2007 2:39:32 AM

    erloas said:
    While the rest of the SI system uses even base 10 numbers, it really doesn't make sense to use them in the binary world of computers. Sure using a base 10 system in everything else makes a lot of sense because we are using a base 10 numbering system as well. But to try and use a base 10 numbering system on a base 2 system doesn't make sense at all. I mean if you are going to use names that don't actually corrispond to anything then you may as well take everything back to the imperial system where unit names change on whatever value comes to mind at the time.


    You've got it backwards - it's the "My Computer" that's applying a base 2 system to a base 10 world, no the other way around.

    500GB = 500,000,000,000 - or 500 billion bytes. And that's exactly what your hard drive has on it. Your file browser is simply being *lazy* and saying "1024 bytes is close enough to one kilobyte," so I'm going to say that one kilobyte is the same as 1024 bytes (which it isn't). From there the discrepancy just grows because it decides that since 1KB*1KB = 1MB, 1024bytes*1024bytes has to equal one MB. (And then again from MB to GB.)

    Believe me when I tell that your base 2 hardware still counts in base 2, and doesn't care what base system we add it up in. But humans count in base 10. (Well, in the modern day we do). And when a human counts up 500 billion bytes, that's 500 GB. Not 465 GB, because computers use base 2.

    Look at it like this. I lay out 500,000,000,000 pennies on my kitchen table (it's a big table). I group them into groups of 1024 (just like a computer groups its bytes). Does my table have 500 Gigapennies, or 465 Gigapennies on it?

    Yup, you guessed it right. Whether those pennies are grouped into groups of 1024, no groups at all, or groups of 7293 (just to be difficult), there's still 500 Gigapennies. Because 1 Kilopenny = 1000 pennies, not 1024 pennies, or 7293 pennies, even if my table is set up as a base 2 system or a base 7293 system.
    February 3, 2009 6:48:24 AM

    Well that's a kinda curious standard... I just bought a Hitachi HDP725050GLA360 500 GB drive and my BIOS reports it as 500.1 GB. Windows Vista Ultimate only reports it as 465.73 GB. Let's take a quick trip down memory lane (My memory, not the PCs). Now, I remember way back in DOS and Win3.x that what your BIOS reports is the same as what your OS said it was. But when Win95 came out, it said something different than what your BIOS or DOS reported. It took me aback at the time that my OS would misreport the hard drive space. Of course, at the time Microsoft said that there were no reporting errors but the same 600 MB drive I had DOS 4 and Win3.1 on was being reported as 536 MB by Win95. It took a while but Microsoft eventually told me that "Windows uses a percentage of your drive for critical system functions. This is what causes the misreporting issue."

    Nowadays, considering the lax standards in truthful reporting to consumers, however, who knows what the real issue is. Certainly not I.

    But my BIOS reports my new Unpartitioned drive as 500.1 GB.

    You figure it out.
    !