Format CF card or delete images?

Mark_Cohran wrote in post #7495978
Just a quick question - How do you "wear out" locations on a flash memory device? I can understand it for magnetic media, but I'm not sure I quite understand how that would work for solid state.

Simple version: NAND RAM works very similar to normal RAM, aside from needing a constant voltage to refresh its state. Contrary to what seems logical, each cell (bit) has a certain threshold for what is 0 and what is 1. Much like on magnetic media, a tiny remnant of the last write remains. Eventually you hit a threshold where the voltage levels become indistinguishable to the controller - is it a 1 or a 0? - and at that point that block cannot be read properly. As you write to NAND RAM, the voltage levels on each block are checked. If they're starting to get into the dangerous territory, that block is marked bad (long before it actually would be bad) and the block is written elsewhere.

silvrr wrote in post #7495830
Intresting. I have noticed my new 40d doesnt have a delete all option like my 400D did. So I have been deleting large numbers of files in camera rather than one by one using the erase button (usually when I am experimenting or just goofing off).

I was wondering if this would have any undesired effects if its done alot. Ill have to check back on this thread.

Look under the left blue play tab under the menu for erase images.

Mark001 wrote in post #7496018
Since this is flash, you are going through a controller that translates writes from a logical sector to a physical sector. While a superblock may always be in the same logical sector, repeated writes to this sector will cause it to be rewritten to a new physical sector in the flash. Better controllers will even move static data to evenly wear the flash parts to extend their life.

I'm aware of write mapping, however cheaper/older cards don't do this nearly as well. Either way, there still is a set of blocks that are used by the remapper to keep track of where the filesystem's start is, and that is the superblock that I was talking about. The superblock isn't the filesystem, it's the first 512 bytes of any media, and the controller needs that to initialize so it can find the media.

It's been a while since I've worked with I/O controllers, so superblock might be the wrong word for this, however my point is that the first 512 byte block must remain in a place where the controller always knows where it is, and with remapping, well it still needs to remain in the same place so the controller knows where to start when it's powered on.

Thalagyrt wrote in post #7495958
Lastly, unlike regular write blocks, the superblocks on any storage device remain in the same locations no matter what. Repeated formatting will wear out the locations of the superblocks much more quickly than if you never format the card and just erase images, as those superblocks will not be touched aside from reads to determine the filesystem type. If that location dies, the entire card might as well be useless. Write distribution will occur for the filesystem's FAT entries, inodes, etc. depending on filesystem, but not for the superblocks.

This I don't believe. Sorry. This is not a card that has a mini mechanical HDD in it that writes and erases with magnetism. We are talking about MEMORY here, right?

I think I will end up getting grey before I wear out a CF card by formating.

Most memory type chips have 150 000 hours of use...that's about 20 years. Even the boot sectors on HDD's don't wear out that fast. I have hdd's working great loading windows every day after 12 years of use. WD80GB to give you an idea.

They would not give a Limited lifetime warranty on my Lexar Pro cards if this was the case. It would be more like a 2 year warranty. All the power to formatting!

gdl357 wrote in post #7496054
This II don't believing. Sorry. This is not a card that has a mini mechanical HDD in it that writes an erases with magnetism we are talking about here, right?

I think I will end up getting grey before I wear out a CF crd by formating.

Most memory type chips have 150 000 hours of use...that's about 20 years. Even the boot sectors HDD's don't wear out fast. I have hdd's working great loading windows even after 12 years. WD80GB to give you an idea.

They would not give a Limited lifetime warranty on my Lexar Pro cards if this was the case. It would be more like a 2 year warranty. All the power to formatting!

Either way the cards will last a very long time. NAND memory isn't rated in hours of use, it's rated in write cycles. To be completely honest, you could do about 100k formats before you'd notice problems. By that time you'll probably have replaced the card anyway. And regarding hard drives, I have a 5.25" drive from back in the late 80s that still works.

Whenever I clear my card I format.

Thalagyrt wrote in post #7496073
Either way the cards will last a very long time. NAND memory isn't rated in hours of use, it's rated in write cycles. To be completely honest, you could do about 100k formats before you'd notice problems. By that time you'll probably have replaced the card anyway. And regarding hard drives, I have a 5.25" drive from back in the late 80s that still works.

So, from a user's practical standpoint, formating wouldn't be anymore destructive than erasing the files.

Mark_Cohran wrote in post #7496115
So, from a user's practical standpoint, formating wouldn't be anymore destructive than erasing the files.

Yea, after some further thought I realized that, and feel like a total idiot for getting into a debate about it. Haha.

I'm so used to seeing embedded devices where logfile writes and such can kill flash memory very quickly, that it made me bring that school of thought over to photography.

silvrr wrote in post #7495830
Intresting. I have noticed my new 40d doesnt have a delete all option like my 400D did. So I have been deleting large numbers of files in camera rather than one by one using the erase button (usually when I am experimenting or just goofing off).

I was wondering if this would have any undesired effects if its done alot. Ill have to check back on this thread.

I believe the delete all is now a function in the menu (with the lock and unlock images).

I transfer my cards using an external reader. Since I have been using digital cameras, 2000, I just delete from the PC. I may, once in a blue moon format, in camera, but that's usually because I forgot to delete the images from the card before putting it into the camera. An extremely rare event.

nphsbuckeye wrote in post #7496029
Actually, you can recover formatted CF cards. I know from personal experience.

data can be recovered from reformatted disks until the data has been overwritten. In other words, a full format, where everything is overwritten with a zero, makes it extremely difficult to recover data. Places like the CIA will overwrite all of their data multiple times.

toxic wrote in post #7496287
data can be recovered from reformatted disks until the data has been overwritten. In other words, a full format, where everything is overwritten with a zero, makes it extremely difficult to recover data. Places like the CIA will overwrite all of their data multiple times.

It's amazing what the expensive toys can do when it comes to data recovery!

I always format my cards in camera (never with PC/Mac) unless I forget to do so and start shooting than I lock new images and delete the rest. Anyway, I always had a feeling that formating is better and faster than deleting...

I've always format my card in the camera when I'm done uploading to my pc.

I always use a card reader or PCMCIA/CF adapter for my lappy.. I transfer the images I need via EOS Viewer Utility then delete all images when I've finished..

I'll in camera format every few weeks.. As of now I've not had any corrupt images (touch wood)..