Re: SD Card limitations


"Steve McPheters" <removesdmcpheters@xxxxxxxxxxx> wrote in message
news:%23kAVOzC7FHA.1248@xxxxxxxxxxxxxxxxxxxxxxx
>I am not certain where to ask this.
>
> I use a Toshiba 740e PocketPC 2002 Handheld. I am using Delorme Street
> Atlas Handheld with a Delorme Bluelogger GPS and a Socket CF Bluetooth
> card.
>
> The problem I am having is that I can't fully load any SD card. Right now
> I have a 256 MB SD card loaded with 174 vector maps from Delorme Topo
> 2005. I use a ScanDisk USB multi card reader to load the card. I reach a
> certain point and it tells me it can't create files or folders. The 174
> files take up 106 MBs. This is the most I have ever gotten.
>
> I have read that it is possible that the card my be corrupt. I have
> reformated and still get the same results. It doesn't happen only on this
> card, but on my 64 and 128 meg cards, too. They aren't all from the same
> manufacturer.
>
> I, also, read that it is best to format cards on the device they will be
> used for. Downloaded a utility to do this, called Pocket Mechanic. This is
> how I got it loaded to 106 megs. Still ends up choking.
>

There are limits to the number of entries in the root directory if you have
all of the files located there.
And each file will have some wasted space- each file won't use complete
allocation units meaning there will be some unused (and unallocatable) space
for each file. On average this will be 50% on the allocation unit size. So
multiply the number of files by this space and that will give an idea of
what you may 'lose' because of the way disk filing systems work. Remember
that is a nominal average and your lost space can be anything from 0 up to
double that figure. You need to examine details of your format to find out
what that allocation space is.



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