Re: SD Card limitations

Steve,

It would be appreciated if you follow the flow of posting. Your jumping to
top posting loses the thread of the conversation making it hard to follow.
Many people wont try to follow the order when you mix it up like that so you
are losing potential help.
The original order used to be bottom posting until MS came on the scene. I
really don't mind which way so long as it is just one way, not mixed. Some
people won't reply to the 'wrong' way- see which way is generally used in a
newsgroup and use that way when replying, but do follow the existing flow in
longer posts please.

Reply at the *end* of this post, the same as Linker3000's reply.



"Linker3000" <Linker3000@xxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:437f0543$0$23295$db0fefd9@xxxxxxxxxxxxxxxxx
> Steve McPheters wrote:
>> Alan,
>> What would be the best scenario to utilize the most space? Should I
>> have the larger files in separate directories?
>>
>> "Alan" <alan@xxxxxxxxxxxx> wrote in message
>> news:dllekd$hra$5@xxxxxxxxxxxxxxxxxxxxxxx
>>
>>>"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.
>>>
>>>
>>>
>>
>>
>>
> Create a folder in the root called, say, 'maps', and put them in there -
> may get over the FAT root file limit.

That's fine *if* that is the problem but I suspect it's not.

FAT32 has limits to its' applicability- there are minimum volume sizes which
is your problem here. There is a theoretical maximum volume size of 2
Terabytes. There is another issue here- the space allocated to the disk
directory structure is higher for FAT32 than FAT16, it gets really massive
for very large volumes.

For FAT32 the minimum volume size is around 260 Mb meaning the card you use
really needs to be 512Mb or larger. This means your card is just too small
to format as FAT32.

Since you are pursuing this I will go a little further with the info for
you. Bear in mind the word averages, your specific situation may well be
different.

FAT16
Disk size Cluster Size Efficiency
128-255Mb 4Kb 96.6%
256-511Mb 8Kb 92.9%
512-1023Mb 16Kb 85.8%
1024-2047Mb 32Kb 73.8%
>2047Mb 64Kb 56.6%

FAT32
>260Mb 4Kb 96.6%
>8Gb 8Kb 92.9%
>60Gb 16Kb 85.8%

I'll let you work out the possible implications to your circumstances, but
don't expect miracles- the 'lost' space is more pronounced on larger
volumes.

You still haven't indicated the number of files on your card or storage
location of the files. And there are still other possibilities beyond those
discussed so far. Perhaps your full card is not addressable or seen by your
pda? If you have a card reader run chkdsk or scandisk, it is possible that
lost clusters can be reducing your available space or a formatting error not
allowing it all to be used. Clusters can be marked as unreadable reducing
your space. Disk utilities can help identify these things. The tools to
check are available on your PC and you probably get them for your ppc too- I
prefer the PCs' tools for these jobs .


.

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