Garmin GPS - SD card

Author

SD card

Linea Recta

2007-04-17, 10:33 am

Recently bought a 2GB SD card and it seemed already formatted as FAT. So I
left it that way and wrote the maps to it.
But thinking about the formatting: is it possible and preferable to format a
SD card of this size as NTFS?
Or at least FAT32?

--
regards,

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| \/ |@rk
\../
\/os

Kent Friis

2007-04-17, 10:33 am

Den Tue, 17 Apr 2007 14:37:31 +0200 skrev Linea Recta:
> Recently bought a 2GB SD card and it seemed already formatted as FAT. So I
> left it that way and wrote the maps to it.
> But thinking about the formatting: is it possible and preferable to format a
> SD card of this size as NTFS?

Only if you are going to use it in Windows-based (CE, NT embedded)
devices. Don't expect it to work in anything else.

> Or at least FAT32?

For most things, FAT12, FAT16 or FAT32 isn't considered different, they
are just different "versions" of FAT. So if the package / manual just
says "FAT", it's probably FAT32.

/Kent
--
"So there I was surrounded by all these scary creatures
They were even scarier than what Microsoft call features"
- C64Mafia: Forbidden Forest (Don't Go Walking Slow).

Linea Recta

2007-04-17, 3:33 pm

"Kent Friis" <nospam@nospam.invalid> schreef in bericht
news:4624c1c6$0$9027
3$14726298@news.sunsite.dk...
> Den Tue, 17 Apr 2007 14:37:31 +0200 skrev Linea Recta:
I[color=darkred]
format a[color=darkred]
>
> Only if you are going to use it in Windows-based (CE, NT embedded)
> devices. Don't expect it to work in anything else.
>
>
> For most things, FAT12, FAT16 or FAT32 isn't considered different, they
> are just different "versions" of FAT. So if the package / manual just
> says "FAT", it's probably FAT32.
>

It says 'FAT' under properties in Windows Explorer (Windows 2000SP4).

--

|\ /|
| \/ |@rk
\../
\/os

Jack Erbes

2007-04-17, 3:33 pm

Linea Recta wrote:

> Recently bought a 2GB SD card and it seemed already formatted as FAT. So I
> left it that way and wrote the maps to it.
> But thinking about the formatting: is it possible and preferable to format a
> SD card of this size as NTFS?
> Or at least FAT32?

FAT and FAT16 are generally synonymous terms for the same format. The
majority of the memory cards come formatted as FAT, some of the newer
and larger ones are FAT32.

I've never found a memory card formatted to NTFS and don't know if any
GPS receivers will use that.

Garmin "invented" the term NT for an improved map data compression
algorithm. It means New Technology but has nothing to do with NT or
NTFS as it was and is used by Micro$oft.

Some cameras have had problems in the past using FAT32 formatted memory
cards. If you have any problem with a card in use I'd try using FAT and
see if that helps.

As I recall the advantages of FAT16 or FAT32 over FAT, there is none
except when you have large numbers of smaller files.

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)

Linea Recta

2007-04-17, 3:33 pm

"Jack Erbes" <jackerbes@adelphia.net> schreef in bericht
news:46251416$0$5770
$4c368faf@roadrunner
.com...
> Linea Recta wrote:
>
I[color=darkred]
format a[color=darkred]
>
> FAT and FAT16 are generally synonymous terms for the same format. The
> majority of the memory cards come formatted as FAT, some of the newer
> and larger ones are FAT32.
>
> I've never found a memory card formatted to NTFS and don't know if any
> GPS receivers will use that.
>
> Garmin "invented" the term NT for an improved map data compression
> algorithm. It means New Technology but has nothing to do with NT or
> NTFS as it was and is used by Micro$oft.

Yes, the list of confusing terms and abbreviations seems to be ever
growing...

>
> Some cameras have had problems in the past using FAT32 formatted memory
> cards. If you have any problem with a card in use I'd try using FAT and
> see if that helps.

Talking about cameras, mine came with a (64 MB) SC card formatted as FAT12.

>
> As I recall the advantages of FAT16 or FAT32 over FAT, there is none
> except when you have large numbers of smaller files.

I believe the formatting has impact on the amount and size of the files,
slack space and the access speed?

thanks,
--

|\ /|
| \/ |@rk
\../
\/os

Jack Erbes

2007-04-18, 7:33 am

Linea Recta wrote:

<snip>
>
>
>
> I believe the formatting has impact on the amount and size of the files,
> slack space and the access speed?
>

Right. And as I understand it, if you write a map file to an empty or
unfragmented card, the file should be in contiguous sectors allowing
faster reads with the sectors being continuous. Of course there are no
mechanics or moving parts involved and everything is at the speed of
light or so. But wear leveling is a factor that has been considered for
flash memory. Some details on that here:

http://en.wikipedia.org/wiki/Wear_levelling

Maybe I need to start keeping some records on the write cycles on my
memory cards? The wiki article says:

"EEPROM and flash memory media have individually erasable segments, each
of which can be put through a finite number of erase cycles before
possibly starting to wear-out and becoming statistically unreliable:
anywhere between 10,000 and 1,000,000 cycles, for example, for NAND
flash devices."

There is a big difference between 10,000 and 1,000,000, now I can start
agonizing over exactly when I should start laying in some good spares. :> )

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)

Linea Recta

2007-04-18, 10:33 am

"Jack Erbes" <jackerbes@adelphia.net> schreef in bericht
news:4625ff56$0$4873
$4c368faf@roadrunner
.com...
> Linea Recta wrote:
>
> <snip>
>
> Right. And as I understand it, if you write a map file to an empty or
> unfragmented card, the file should be in contiguous sectors allowing
> faster reads with the sectors being continuous. Of course there are no
> mechanics or moving parts involved and everything is at the speed of
> light or so. But wear leveling is a factor that has been considered for
> flash memory. Some details on that here:
>
> http://en.wikipedia.org/wiki/Wear_levelling
>
> Maybe I need to start keeping some records on the write cycles on my
> memory cards? The wiki article says:
>
> "EEPROM and flash memory media have individually erasable segments, each
> of which can be put through a finite number of erase cycles before
> possibly starting to wear-out and becoming statistically unreliable:
> anywhere between 10,000 and 1,000,000 cycles, for example, for NAND
> flash devices."
>
> There is a big difference between 10,000 and 1,000,000, now I can start
> agonizing over exactly when I should start laying in some good spares.
:> )

Thanks very much for the link. Actually I have been fantasising for a long
time about this problem of uneven wearout, but I never came upon the
apparent existing term 'wear levelling' and ditto technical solutions. A
good approach to improve life span of media of course, but at the cost of
speed. It would be nice to have software options to swich wear leveling on
of off with a check box.
Afraid is isn't implemented for the SD card I just bought today for the PDA.
On the other hand, I suppose wear levelling isn't in the interest of
commerce, just aiming to boost sales figures...

--
regards,

|\ /|
| \/ |@rk
\../
\/os

emmbeedee

2007-04-19, 10:33 am

On Apr 18, 7:21 am, Jack Erbes <jacker...@adelphia.net> wrote:
>
> There is a big difference between 10,000 and 1,000,000, now I can start
> agonizing over exactly when I should start laying in some good spares. :> )
>
> Jack

The only bright side to this is that no matter what you paid for
whatever memory type previously, it'll be much cheaper as time goes
on... and the chips are getting bigger too.

There are times when I can't wait for some old technology to stop
working so I can justify going for the new.

Whoops, looks like I spilled some coffee into that old P3 laptop. Too
bad, it was working so well. ;)

Emm

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