Real SD card size

If one SD card vendor says its SD cards are 512 Mb, I'm not sure their size
is 512 Mb..

However, I'd like to know what's the max size range and from what features
(physical and software) it depends on. Could you help me?

Max


P.S. A-DATA says "For our 512MB SD card, the real capacity is about 476MB to
498MB"

Paul
Mon May 15 11:26:36 CDT 2006

I'm not sure that I understand the question. Are you saying that different
vendor may define 1MB differently, so the total capacity of a 512MB card
might differ from vendor to vendor? Or that the usable capacity on a given
size of device might vary from vendor to vendor?

The most common cause of free space on a device not matching the total
capacity is the storage of formatting information. On flash devices,
there's also the holding back of some sectors to allow for wear-leveling on
the media, even when the device is nearly full of your data.

What's the problem? If you need exactly 512MB of storage, buy a 768MB SD or
larger...

Paul T.


"Mhaxx" <supermhaxx@despammed.com> wrote in message
news:%23wxbox%23dGHA.1276@TK2MSFTNGP03.phx.gbl...
> If one SD card vendor says its SD cards are 512 Mb, I'm not sure their
> size
> is 512 Mb..
>
> However, I'd like to know what's the max size range and from what features
> (physical and software) it depends on. Could you help me?
>
> Max
>
>
> P.S. A-DATA says "For our 512MB SD card, the real capacity is about 476MB
> to
> 498MB"
>
>

Mhaxx
Tue May 16 08:04:21 CDT 2006

> I'm not sure that I understand the question. Are you saying that
different
> vendor may define 1MB differently, so the total capacity of a 512MB card
> might differ from vendor to vendor? Or that the usable capacity on a
given

Yes, different vendors seem to produce cards might differ from vendor to
vendor. And the difference may consist of many Mb!!!

> size of device might vary from vendor to vendor?

Maybe this is true, too..

> The most common cause of free space on a device not matching the total
> capacity is the storage of formatting information. On flash devices,

Ok, but formatting information should be about "the same" (size) from vendor
to vendor: d'you agree? What I don't understand is that one vendor produce
SD card with X Mb of free space and another with Y Mb, and X and Y could be
very different!

> What's the problem? If you need exactly 512MB of storage, buy a 768MB SD
or
> larger...

I need 488 Mb of free space, and I've noted some vendors give me this amount
and others no (many Mb less). How to explain this thing?

Max

Paul
Tue May 16 14:14:20 CDT 2006

No, formatting information can be anything. If you reformat it on your PC
before you use it, then you can control the cluster size, which is the main
parameter in the format which matters (it controls the size of the FAT).
Two different manufacturers can format their flash devices in completely
different ways, hence, different free space from the factory.

We've already *explained* it. Now it's time to get over it and buy
appropriate cards!

Paul T.

"Mhaxx" <supermhaxx@despammed.com> wrote in message
news:%23QtX0iOeGHA.3888@TK2MSFTNGP04.phx.gbl...
>> I'm not sure that I understand the question. Are you saying that
> different
>> vendor may define 1MB differently, so the total capacity of a 512MB card
>> might differ from vendor to vendor? Or that the usable capacity on a
> given
>
> Yes, different vendors seem to produce cards might differ from vendor to
> vendor. And the difference may consist of many Mb!!!
>
>> size of device might vary from vendor to vendor?
>
> Maybe this is true, too..
>
>> The most common cause of free space on a device not matching the total
>> capacity is the storage of formatting information. On flash devices,
>
> Ok, but formatting information should be about "the same" (size) from
> vendor
> to vendor: d'you agree? What I don't understand is that one vendor produce
> SD card with X Mb of free space and another with Y Mb, and X and Y could
> be
> very different!
>
>> What's the problem? If you need exactly 512MB of storage, buy a 768MB SD
> or
>> larger...
>
> I need 488 Mb of free space, and I've noted some vendors give me this
> amount
> and others no (many Mb less). How to explain this thing?
>
> Max
>
>

Mhaxx
Wed May 17 03:09:08 CDT 2006

> No, formatting information can be anything. If you reformat it on your PC
> before you use it, then you can control the cluster size, which is the
main
> parameter in the format which matters (it controls the size of the FAT).
> Two different manufacturers can format their flash devices in completely
> different ways, hence, different free space from the factory.

Sure, but not so different! Take a look at this:

SD CARD 1: FAT32 => 512.139.264 byte (= 488 Mb)
SD CARD 2: FAT32 => 496.604.288 byte (= 471 Mb)

They are two SD cards produced by the *same* manufacturer and bought
together: I think different manufacturers can format their SD cards with
different free space, but no 17 Mb! (=488-471) Moreover if the manufacturer
(this is my case) is the same for the all the SD cards!!! :-O

Excuse me, how can you explain this?!

> We've already *explained* it. Now it's time to get over it and buy
> appropriate cards!

Please, tell me where to read about it.. I can't find prev. conversation..

Thank you so much,

Max

Paul
Wed May 17 12:05:38 CDT 2006

I don't find any need to explain it down to the byte level. Reformat both
cards with the same parameters and see what happens, if you feel driven to
research this further.

If you can't live with cards from that manufacturer sometimes having
different formatted sizes and free space numbers, use a different
manufacturer or use bigger cards. My belief is that the two things that I
mentioned before account for this: formatting differences and wear-leveling
space set aside.

I can't figure out what your problem is with this -- it seems like no big
deal to me.

Paul T.

"Mhaxx" <supermhaxx@despammed.com> wrote in message
news:%23ZGQciYeGHA.1260@TK2MSFTNGP05.phx.gbl...
>> No, formatting information can be anything. If you reformat it on your
>> PC
>> before you use it, then you can control the cluster size, which is the
> main
>> parameter in the format which matters (it controls the size of the FAT).
>> Two different manufacturers can format their flash devices in completely
>> different ways, hence, different free space from the factory.
>
> Sure, but not so different! Take a look at this:
>
> SD CARD 1: FAT32 => 512.139.264 byte (= 488 Mb)
> SD CARD 2: FAT32 => 496.604.288 byte (= 471 Mb)
>
> They are two SD cards produced by the *same* manufacturer and bought
> together: I think different manufacturers can format their SD cards with
> different free space, but no 17 Mb! (=488-471) Moreover if the
> manufacturer
> (this is my case) is the same for the all the SD cards!!! :-O
>
> Excuse me, how can you explain this?!
>
>> We've already *explained* it. Now it's time to get over it and buy
>> appropriate cards!
>
> Please, tell me where to read about it.. I can't find prev. conversation..
>
> Thank you so much,
>
> Max
>
>