Rebel XTI slow to write to memory card

Jürgen Exner wrote:
John McWilliams wrote:
Jürgen Exner wrote:
John McWilliams wrote:
Jürgen Exner wrote:
Snipped bits out
Formatting in camera is way faster than erasing.
Anyway, I doubt that. Ctrl-A == "Delete" == "Enter". That's jsut
three keys to press and at least on the 2GB cards I am using it never
took more than a few seconds for the delete to finish.
That's on the computer. I was speaking of on-camera operations, which

Sorry, I didn't know that because you didn't mention it. Yes, an camera
a format is certainly easier to initiate than an in-camera delete all
files.
Which on the other hand is irrelevant when the delete all files is done
before swapping the card from the computer back to the camera.

are safer than doing it via computer.

I disagree. Delete is delete, no matter which device performs the
operation.

You're missing the larger picture. If you wait till just before the next
shoot, you have an additional pure source of backup.

And while one can format via Mac
to FAT, why take the extra time?

Again, I disagree with both preconditions that are implied in your
question:
- that it takes longer to format in-computer than in-camera

Since I recommend against on-computer deletion or reformatting, the
above comparison is meaningless, and not implied by me.

- and that a format is necessary or even just superior to a delete-all
files

Didn't say necessary, just superior.

[personal attack snipped]

Not exactly an attack. I wrote:

You jumped in gratuitously, and were rude and grating.

I asked if I had somehow insulted you previously. Had I?

The first part is a statement of fact, at least about the gratuitous
part, and if others feel I am way off base by characterizing your
comments, then do say.

You still fail to answer the simple question.

--
john mcwilliams

Phisherman wrote:
However, if you really want to wipe off images so they
can not be recovered easily, reformat the card.

Formatting does _NOT_ erase file data blocks, it merely recreates the
meta-information like free-block list, directory, ... from scratch.
Any file recovery program can recover data from a newly formatted drive
as easily as from a drive where the directory got corrupted.

If you actually want to erase the file data itself then you need to
overwrite it.

jue

Wolfgang Weisselberg wrote:
Jürgen Exner wrote:

Doesn't matter much. As long as the file system itself isn't damaged
there isn't any difference between removing all file information from
the directory ( = deleting all files) and recreating the file system (=
formatting), assuming your are choosing a file system that is compatible
with your cameras and OS.

Of course thre is a difference. Any comparison program run
on the image of a freshly formatted card and one that had
files and had them deleted will show non-trivial difference
(assuming a FAT file system)

Down on the nitty-gritty binary level I agree. How much those
non-trivial differences are also relevant, well, I wholeheartily agree
with what you wrote below:

If these differences will upset your camera, even though they
should not, depends a lot on the implementation of the FAT drivers
in the camera.

"even though they should not" being the key phrase.

jue

Jürgen Exner wrote:
John McWilliams wrote:

I doubt you'll do anything but argue and be dense when you lose.
However, on the off chance, and for benefit of others: The following

Ok, I had it. Take it whatever way you like, I don't care any mo

***PLONK***

!

That's pretty much what those who come simply to argue do when they've
lost.
Too bad he didn't have the guts to actually address what he left out.

--
lsmft

Jürgen Exner wrote:

That's on the computer. I was speaking of on-camera operations, which
are safer than doing it via computer.

I disagree. Delete is delete, no matter which device performs the
operation.

Incorrect.

"Delete" is not an atomic operation that is always done the same way.
Different file systems can handle the operation different ways. In
particular, cameras don't usually implement the same filesystem as
does a computer. They use a simpler (and smaller) subset that fits
the constraints of the camera but cannot cope with the myriad of
variants that a full implementation in a computer could cope with.

And while one can format via Mac
to FAT, why take the extra time?

Again, I disagree with both preconditions that are implied in your
question:
- that it takes longer to format in-computer than in-camera
- and that a format is necessary or even just superior to a delete-all
files

Format often can be superior since it restores the card to a clean
state while deleting all file may not delete all directories and leave
gaps in the allocation table.

--
Ray Fischer

Jürgen Exner wrote:
Wolfgang Weisselberg wrote:

If these differences will upset your camera, even though they
should not, depends a lot on the implementation of the FAT drivers
in the camera.

"even though they should not" being the key phrase.

Yes, obviously.

Unfortunately, every Kernel-OOPS, every bluescreen, every accident
caused by faulty, bad, mis-placed or mis-designed materiel,
etc. all happen "even though they should not".

The wise man wears safety belts even though they shoud not be
needed --- should *never* be needed. And formatting is still
faster.

-Wolfgang

rjn wrote:
Jürgen Exner wrote:

If you actually want to erase the file data
itself then you need to overwrite it.

And this is worth doing. Create a large data object

Whatever a 'large data object' may be ... in my world there
are only files, e.g. created by
dd if=/dev/urandom bs=1G count=WHATEVER
and sized to fill the storage medium (card, stick, whatever).
:-)

and write it to the card under different file names
until the card is full. Read them all back and
then delete.

On a new card, this confirms that the capacity the
card reports is what the card actually has,

If you are quite unlucky, reusing the same data can get you a
false negative ... i.e. you believe the card is OK, when in fact
it's capacity is just large enough for the 'large data object'.

and and confirms that no cells or blocks are defective.

Nope. Unless you are talking to the raw flash chip, a controller
will (or should, at least) level your write requests, remap
defective or marginal blocks to reserve units, etc.

You'll probably find that each flash unit will have some
defective blocks mapped out (the same is true for hard
drives) if you circumvent the controller.

On an existing card, a full-write both obliterates
any existing image rasters

Don't bet on that if you are up against a major criminal
organisation or the NSA ... see remapped blocks for one obvious
data leak possibility. There are probably others.

and confirms that no cells or blocks have gone bad.

See above, no, at best you can say that the controller
handles them currently.

-Wolfgang