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k800 mem card shortage |
max_wedge
Joined: Aug 29, 2004
Posts: > 500
From: Australia
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you should get roughly 933MB (depending on format and so on)
Manufacturers use decimal to measure capacity, hence 1 Kb = 1,000 bytes. OS's use binary, so in the OS's calculation, 1 KB = 1024 bytes. Therefore the "gigabyte" on a 1GB memory card, is smaller than what the OS thinks of as a "gigabyte". If you divide the decimal capacity by 1.074 you will get close to the capacity that the computer will report (in binary bytes:- 1,000,000,000 decimal bytes = 1,073,741,824 binary bytes)
Basically, the manufacturers are correct: they use decimal maths to measure the capacity and the value they give is the exact byte for byte capacity of the drive. In other words, on a 1GB drive, there is 1000 MB of capacity. However for software developers, counting in multiples of 8 makes more sense, so early in the game software developers called 1024 bytes "1 Kilobyte" for convenience, even though drive manufacturers were already using 1 Kilobyte to refer to 1000 bytes.
And here we are today, with people thinking they are getting ripped off.  It's no different to measuring distance, for example 1mile = 1.6km but it's still exactly the same distance. 
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File System Tweaks for the K750 K750 Tricks
[ This Message was edited by: max_wedge on 2006-08-21 14:06 ] | |
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max_wedge
Joined: Aug 29, 2004
Posts: > 500
From: Australia
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Quote:
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On 2006-08-21 11:11:02, altemyr wrote:
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On 2006-08-21 10:02:38, sapporobaby wrote:
Everyone knows that a 512 or 160 or 20 gig drive will yield different sizes than what is actually represented on the drive. However, clusters formatted in FAT, or NTFS, FAT 32. 4K will yield different results than an 8K file clusters. The bottom line is that you never get what is advertised and EVERYONE should know this.
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Well, I do understand that, due to file system, clustering, block sizes etc, the actual usable disk/memory space is less than the raw size, but what I don't understand is, why the usable size is less on a 512 MB M2 than on a 512 MB MicroSD/Transflash
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Every memory card has a certain amount of it's capacity reserved for internal use (not file system, that's another issue) - this size is different for the M2 from what I understand.
BTW, the file system on a memory card doesn't take up a lot of space, only a couple of megabytes MAX. on a 1GB card. It's not the formatting that "consumes" the megabytes, it's mostly down to the disparity between the decimal and binary definition of a kilobyte.
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altemyr
Joined: Jan 21, 2002
Posts: > 500
From: Stockholm, Sweden
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On 2006-08-21 15:01:58, max_wedge wrote:
it's mostly down to the disparity between the decimal and binary definition of a kilobyte.
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Well, 1024 instead of 1000 is a difference of 2.4%, and when you go to MB or GB, it's 1024^2/10^6=4.9% and 1024^3/10^9=7.4% respectively, i.e a 1GB memory card should contain about 948 MBytes, so it does not explain the entire memory loss. However, the file system can be optimized for faster access at random searches, and that might require some overhead in form of index files, binary search trees etc, which have to be stored in files on the memory card, invisble for the user. |
max_wedge
Joined: Aug 29, 2004
Posts: > 500
From: Australia
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Quote:
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On 2006-08-21 18:56:53, altemyr wrote:
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On 2006-08-21 15:01:58, max_wedge wrote:
it's mostly down to the disparity between the decimal and binary definition of a kilobyte.
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Well, 1024 instead of 1000 is a difference of 2.4%, and when you go to MB or GB, it's 1024^2/10^6=4.9% and 1024^3/10^9=7.4% respectively, i.e a 1GB memory card should contain about 948 MBytes, so it does not explain the entire memory loss. However, the file system can be optimized for faster access at random searches, and that might require some overhead in form of index files, binary search trees etc, which have to be stored in files on the memory card, invisble for the user.
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Most people do get 930-960MB on a 1GB card, so I'm right imho. The poster who got 811MB has a faulty card, simple as that. Or they formatted it with a rediculously large cluster size (actually that still wouldn't explain the 811 capacity).
Formatting with large cluster sizes will improve the efficiency of the file system, and reduce usable memory, however to lose 100MB??? As I said before, formatting takes up less than a few MB in capacity - the loss of 100MB simply can't be explained by file system overhead.
A further 10MB or so is used by the card itself (not "file system" but just internal storage for the mem card controller on the card itself). This still doesn't explain a loss of over 100MB.
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sapporobaby
Joined: Sep 14, 2003
Posts: > 500
From: Finland. Kuwait maybe :)
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Hey Max, he might have mistyped. He may have meant 911.
*edited on a Mac of course. Mac: There is no substitute*
N82(YES), iPhone 3G, Shure es530, Nikon D300, more stuff. No more SE stuff, why am I still here? | |
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Posted: 2006-08-21 14:47
