What this means is that even after you format the card the controller will continue using parts of the card that have not yet been written to until each storage location on the entire card has been written to before it will go back and begin using the locations that have already been used.įormatting regularly helps the memory controller on the card do a better job of wear leveling.
So the controller tries to ensure that each storage location of the entire card is written to roughly the same number of times over the life of the card. The number of write cycles each bit on a flash memory card can handle before it fails is very large but it will eventually wear out.
They do this for what is known as load balancing/wear leveling.įlash memory has a limited number of write cycles it can tolerate before it fails. The way flash memory cards (and USB flash drives) work is that the memory controller on the card assigns different areas of the card for specific directory locations each time the card is formatted. One of the thing the buyers look at is how much reserve memory remains on the chips after the bad sectors have been mapped out at the factory.Īnother advantage of regular formatting is better wear leveling performance. So do the off-brand names, but they usually buy the leftover components that may or may not have been good enough to pass the QC of the major brands' buyers. All of the major brands (Lexar, SanDisk, Transcend, Kingston, etc.) get their components from the same handful of suppliers that actually manufacture the memory chips and controller chips. The greater the amount of memory that must be mapped out, the less reserve memory is available on the card for the controller to use as other sectors fail later on. One of the common differences between top name brand memory cards and generic/no name memory cards is the number of bad sectors mapped out of the card's total memory before it leaves the factory. When a bad sector is identified, the memory controller will block the use of the bad sector and replace it with some of the 'spare' memory on the card. Most memory cards have a bit more memory than their listed capacity. stolen - but it also means, that you should be sure you really want to wipe the card.īeyond the particulars of each specific camera and how they may handle cards formatted on other devices, there are also benefits to regularly formatting flash type memory.īad sectors are mapped out by the card's controller. This can be a good thing, so files do not fall into wrong hands if the card is e.g. It is your choice, but if it saves you trouble just once, it was worth formatting it in camera.Ī little side note: If you format a SD card in camera, in a small portion of cameras (e.g. So you balance your need of flawless operation of your camera vs some write cycles on a comparatively cheap SD card. In the end, formatting in camera is an additional step, that makes sure that the card is in exactly the condition that your camera likes best. However, your camera might cope well with that and have no noticeable problems. The camera then complains and tries to rebuild the database, which might fail.
If you then delete images on the computer, the database is not updated, leading to inconsistencies. my Sony a7 III) even write a little database to the SD card, keeping track of the images. This includes a card that was formatted in computer as well as making sense of temporary or meta files that were written by a computer. While cameras are really good at writing images to an SD card, most of them are only so-so when it come to reading a modified SD card. As the sentence above was a quote from me, let me elaborate:
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