Canon CF Card Formatting Question

[rpcrowe]

I was perusing the fine book, “David Busch’s Compact Field Guide to the Canon EOS 7D” when I came upon a reference to formatting a CD card which I don’t understand...

Page 69 under Format tells how to format a CD card in the standard method of selecting “format” from the menu.

However, it continues to say in brackets "(The optional low level format invoked with the Trash button is a slower, but more thorough reformatting that can help restore a memory card that has picked up some bad sectors that aren’t locked out by the normal format step)".

I have always formatted my CD cards using the Menu Format command and assumed that this is the most efficient way to prepare a card for shooting.

Would using the Trash button be a way to see if I can “fix” a CF card which is giving me problems. In my many years of DSLR use, I have had only one CF card which malfunctioned (which says a lot about the durability of CF cards).

I threw away the card after several tries to reformat in the camera and use it. Should I have tried the Trash button before I dumped the card into the trash (pun intended)?

[Glenn NK]

Interesting question Richard.

I've always formatted my cards in the camera after transferring the images to the HDD; most of us know that deleting them rather than formatting is not a good approach.

I DL'd both the original and latest 7D manuals, and under formatting the CF card, there is no mention of an optional level format method.

Is the formatting Busch refers to done in the computer?

Since CF cards are not brand specific, it would seem that a card could be formatted in a computer, then re-formatted in the camera (just to be safe).

I just formatted a USB drive and there is no mention of any options other than Format (Win XP), and I'd think that the same options would be available for CF and USB drives.

Glenn

[Inkanyezi]

Not all cameras are capable of doing a low level format, but if they are, they should also mark unreliable sectors as bad. The normal "formatting" procedure is only to rewrite the File Allocation Table to an empty one, and then to add the directories that should be on the card. Those directories will also be written automagically to a card that is freshly formatted in the computer, when the card is put into the camera and the camera turned on, provided the card is formatted to FAT (any flavour that the camera accepts, 16. 32 or 64).

So essentially, a high level format will do almost exactly the same thing as erasing all files on the card, and that is what a camera usually does when you format in the camera. This is different from the erasing that is dissuaded, as when you erase some random files on a card, you upset the order of how they are stored, which may cause fragmentation.

Cameras have very rudimentary operating systems, and they may get confused by a fragmented file system, which may cause malfunction. Also, if you should need to restore lost files from a fragmented system, it might become unfeasible, while you can always restore all files from a file system on a card that is not fragmented. If you decide to remove files from the card in a camera, always remove the last ones taken, but never any files where other images were taken after. In that way, you may keep the file system tidy, so that it could be restored if by chance it becomes corrupt.

Also, a fragmented file system makes file write slower, which may interfere with shooting video. That is the reason why a newly formatted card is recommended when you shoot high resolution video. If the write speed for the card is close to the video recording speed, fragmentation may cause it to go under that speed, which will usually stop recording.

[davidedric]

I don't use CF cards and haven't had the problem. But, assuming you can read your card direct on whatever computer you use, wouldn't that be a better place to reformat? Apologies if this is a dumb suggestion.

[Inkanyezi]

I don't use CF cards and haven't had the problem. But, assuming you can read your card direct on whatever computer you use, wouldn't that be a better place to reformat? Apologies if this is a dumb suggestion.

Not at all a dumb question. If your camera is not capable of low level formatting, it is a good idea to do a low level format occasionally in a computer, provided your system does that for you and you choose the right file system. The card itself will keep track of what memory cells that are marked as "bad" and will not use them, and the computer will warn you when the card eventually becomes too bad to be used with confidence.

But generally, cards are very reliable, and it is mostly sufficient to do a high level format, i.e. format in the camera, to avoid fragmentation, which is more likely to become a problem than bad memory cells.

[Colin Southern]

Hi Richard,

In short, a low-level format deals to the "actual media" (see below as to why that's in speech marks) where the data is stored - marching through each and every location looking for bad spots. A normal format only deals to the file system on the media. Kinda like inserting a new table of contents and index in a book - all of the content is still there, but you just can't see it by looking at the index and TOC.

If a card has bad spots then it's time to get rid of it; a low-level format might identify them, but if some have gone bad then a LOT of others may well be pretty close because the controller on the card routinely changes the physical location on the memory chips that are being used to write data into so that the whole card gets a good work out. On the other hand, if a card gets screwed up because - say - a battery went flat in the middle of writing something and screwed up some of the data structures at a sector level then by all means do a low-level format - there's no harm - it just takes a lot longer with big cards.

On a final note - if you do fix a problem with a LL format then be sure to test the entire card thoroughly by filling it to the brim with data and ensure you can read it all (best tested on a PC).

Hope this helps

[Inkanyezi]

If a card has bad spots then it's time to get rid of it; a low-level format might identify them, but if some have gone bad then a LOT of others may well be pretty close

I just said that the computer will warn you when you do a low level format, but I didn't stress it, as Colin does. If there are bad cells on a card, dump it and get a new one. You shouldn't use one that is unreliable.

[koolkat]

Hi Richard, I'm also reading Mr. Busch's 7D book, "Canon EOS 7D" 473 pages. In reading this book regarding formatting CF cards, David states that doing so only in the camera is the preferred method and should a problem occur, then a computer format followed by a format in the camera. I've never deleted a picture on the card while in the camera and have had only one card problem which was returned to the maker, replaced and then formatted in the camera. I also just purchased two CF cards used extensively in a Nikon camera, formatted them and they have worked well in my 7D. Not sure if this helps, but my $0.02¢ worth of help. I also enjoy and learn from your postings. Thanks,