Checkerboarding on Flash Cards

[karl.jahr]

Hard disks on computers over time become checkerboarded as files are created and

removed, and as a result, usable space is lost to holes too small to take up

files. That's where defragmentation software has to perform its job.<P><P>

My question is: does one get a checkerboarding effect on flash memory when one

starts removing individual pictures as the card fills up and one needs to make

room for new pictures?

[alec_myers]

I don't think your characterisation of fragmentation on a hard drive is correct; it's not that space is lost - a block of storage is a block of storage is a block of storage, after all. It's that by fragmenting a file into small discontinuous chunks the drive head has to move around a lot while reading the file, which slows the read process. That being the case, seeing as flash cards are solid state and any area can be accessed as quickly as any other, I can't see why fragmentation should be an issue.

[steven_clark]

In fact fragmentation is essentially ignored in favor of wear-balancing the sectors of the drive.

[Ed_Ingold]

Most CF cards are formated FAT16 or FAT32, and fragmentation is an issue due to the large sector size and inefficient FAT algorithms. Not all image files are the same size, plus there are various directories created and used by the camera. At best, fragmentation will make writing image files slower. At worst, the files may be corrupted.

 

The correct procedure is to format the card in the camera after all of the images have been properly transferred and backed up. All the image files can then be stored head to tail, efficiently.

 

There is no wear on an hard disk surface because the head floats on a thin layer of air dragged by the rotating surface. If the head ever touches the rotating surface, know has an "head crash", both the head and disk are destroyed.

[kelly_flanigan1]

One can defrag ones cards.

[Ed_Ingold]

Defrag + Format = Format

 

Defragging is a waste of time. The CF card is for shooting, not storing snapshots. You need a computer to defrag the card - why not just download the images, back them up and be done with it?

[alec_myers]

"In fact fragmentation is essentially ignored in favor of wear-balancing the sectors of the drive."

 

I wonder if Steve meant wear-balancing the flash-card - see for instance http://en.wikipedia.org/wiki/Wear_levelling

[rainer_t]

-- "My question is: does one get a checkerboarding effect on flash memory when one starts removing individual pictures as the card fills up and one needs to make room for new pictures?"

 

Yes. Albeit the technical term generally used for this is "fragmentation".

 

Try to avoid to delete individual images (usually while viewing them in camera). Not deleting them helps recovery software to recover images properly.

 

Whenever you have copied the images to a computer and have backed up them ... then format the card "in-camera" before you use it again. (This is better and faster than deleting all images in-computer).

With this procedure any worries about fragmentation belong to the past.

[my]

Completely agree with Rainer. Defrag a flash drive is pointless because it is not intended as a long term storage solution, just format it before every shooting session and try not to delete photos on it while shooting as this will make files more difficult to recover is something goes wrong with the card.