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I read something sometime ago that erasing instead of format may cause corrupt data in a digicam's memory card. But my question is regarding flash/thumb drive in a similar way, when you want to completely erase all data, is it better to just format than erase?

Additional question: Theoretically which action causes more damage if any to the drive, format or erase?

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In theory, erasing (setting all bits to 0, also termed a "Full Format" by Windows) does more damage. Flash memory has a limited number of times that it can be written, and the more you write to it, the more it degrades. In this scenario, you're writing to the entire device.

In a "quick" format, all that's happening is we change a few bits at the front of the device to say that the rest of the data on the flash drive is meaningless, and available to be overwritten. This will mark the entire device as empty / available, but delays actually overwriting the old data until we actually have new data to replace it with. This saves the flash memory a single write over erasing it (old data -> new data, as opposed to old data -> zeros -> new data).

Unless you are trying to prevent someone else from recovering the information, it's usually just better to format than erase. Erasing won't explicitly cause corruption, though it does put more wear & tear on the drive if it's done repeatedly, could cause the flash to fail sooner than simply formatting it instead. But we're talking long-term-- flash these days is generally designed to withstand more than 100,000 complete erasures before it starts to fail, so I wouldn't worry about it. If a piece of flash memory fails on me these days, it's probably because of a manufacturer defect, rather than because I was erasing it too much.

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Just to clarify, you mean erase = full format, and not simple delete (i.e., delete key from keyboard) ? – IMB Aug 21 '12 at 15:33
@IMB Yes, a delete from Windows Explorer or similar is akin to a partial-format: It's just marking the area owned by that file as available, but doesn't make any effort to erase the actual content. "File Shredders" on the other hand, do take extreme care to overwrite the data content, often multiple times. – Darth Android Aug 21 '12 at 15:37

A 'debate' which exists within photographic circles is about performing a 'format' which is to overwriting the file allocation table (FAT) with a new one plus some (but not all) storage areas within it vs. 'deleting files' which marks a space as available within the FAT. Contrary to what you may have been told, it has nothing to do with zero'ing out a card or completely overwriting data on a given disk/card. Special tools are required to wipe a disk back to '0'.

Unfortunately, those involved in this 'debate' are experts in the field of photography rather than electronics or computing. Particularly this seems to be true for those who seem to carry the most sway...

The proponents of formatting suggest to do it to prevent file allocation corruption issues, but if you have FAT corruption problems then you've got far bigger problems waiting for you that could bite you after each and any click of the shutter.

The opponents of formatting say that excessive writes to a card are a bad idea, which while noble, betwen wear levelling and other techniques and the low volume use of even a professional's cards wearing a camera out is more likely than a flash card.

The reality is do what you like - it makes no difference in the real world.

Incidentally I have experienced FAT corruption issues with my DSLR - for some reason this camera in combination with a (supported) 16gb card will, at some seemingly random point, throw up an error and refuse to shoot any more. Formatting the card cannot prevent this behaviour becasue the camera is the source of the problem. Incidentally the files are fine and popping the card into a reader lets me get everything off it and obviously at that point I delete all the files off the card and the problem is gone and I may then be able to go on and shoot a whole card-full (or not, at my camera's discretion).

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