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#21
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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 |
#22
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Rebel XTI slow to write to memory card
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 |
#23
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Rebel XTI slow to write to memory card
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 |
#24
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Rebel XTI slow to write to memory card
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 |
#25
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Rebel XTI slow to write to memory card
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 |
#26
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Rebel XTI slow to write to memory card
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 |
#27
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Rebel XTI slow to write to memory card
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 |
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