Card Failure (SD)

Started Apr 18, 2013 | Discussions thread
Freeman-Jo Senior Member • Posts: 2,583
Re: +1 and then some

Y Hafting wrote:

One thing that seems to be overlooked by many is the fact that flash memory (This goes for CF's, SSD -drives etc) aren't perfect after a while, there will be errors.

The way to overcome these fault is marking the unusable regions as bad and stop using them. As far as i can see this is at least done when performing a low level format. (this is why the general advice is just formatting the card and starting over again)

On the 6D, you have the option to format "normal" or "low level". On the "normal" format one can only assume that it is only the FAT table that is overwritten-

Thus if there are errors on the card due to faulty writing (either bad blocks or if the write wasn't complete due to camera shut off/ card removed while writing / etc) the "normal" format or deleting the files won't provide a complete fix, and the problem accumulates as the files get more and more fragmented.

Thus to ensure the proper operation of the memory card, one should remember to use the lowest level formatting now and then, in stead of just deleting or using "normal" or "fast" format modes.

Exactly how often a low level format is appropriate, is another issue. Personally i do it typically before events such as going on a holiday. (I have never had card failures on the 30D i had or the 6D).


I don't think the so call "low level format" in camera or many(if not most) of the mobile device is the same as the real "low level format" most computer geeks had to deal with in the past(probably 2 decade ago we had to do some time).  The one that most cameras offer are either a quick format(normal), which basically just erase the index and leave the content intact.  But since the index is gone any device looking at it will think it's blank.  When any or of storage device start to mis-behave regardless of whether it's a flash based or mechanic based this is the kind of format ypu need to avoid.The other kind of format hat some cameras offer, although canon call it "low level", I think the minimum it does is to erase all the partition tables, recrate it and at a minimum a quick format.  Some may offer a real full format, but I don't think thia is usually the case as real full format usually take hours.  If anyone ever format a 4TB harddrive then it take close to a day.

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