Avoiding memory card corruption

paddler4

In a recent thread about which brands of CF cards are safest, Ziggy and one other poster had some suggestions for avoiding corruption. One was not to do field deletions. I have been doing field deletions all the time for the past 18 months, and (knock on wood) I have had no problems at all, but now I am nervous about it. Are there any tests of whether field deletions matter, or is this a case of playing it safe when no one has yet tested it?

ziggy53

paddler4 wrote:

In a recent thread about which brands of CF cards are safest, Ziggy and one other poster had some suggestions for avoiding corruption. One was not to do field deletions. I have been doing field deletions all the time for the past 18 months, and (knock on wood) I have had no problems at all, but now I am nervous about it. Are there any tests of whether field deletions matter, or is this a case of playing it safe when no one has yet tested it?

When memory cards were much more expensive I used to do field deletions, until one day I was shooting some stuff for work and the card became unreadable. I was lucky in that software was available to recover the files and I think I only lost 3 images.

Deleting files on a memory card can create "holes" in the FAT that the controller does not translate properly when trying to allocate memory for subsequent files. You wind up with both fragmentation and even the occasional overwrite. The worst problems occur when the card is completely filled and the controller back-fills, but some controllers apparently also try to fill empty space before the card is full.

This process is further complicated by "write leveling" which attempts to write all blocks the same number of times. (This is much more complicated than hard drives endure.)

Some references:

http://www.digicamhelp.com/accessories/memory-cards/corrupted-memory-card/

http://photonaturalist.net/11-tips-for-avoiding-memory-card-problems/

http://www.consumertraveler.com/beenthere/when-your-camera%E2%80%99s-memory-card-fails-can-it-be-saved/

paddler4

Ziggy,

Thanks.

Dan

W.W. Webster

paddler4 wrote:

Avoiding memory card corruption

1. Use only cards fully manufactured by the vendor/brand (there are very, very few - for example, SanDisk).

2. Always format the card in the camera before use.

3. Never erase files from the card in the camera.

4. Ensure the camera is always switched off before removing the card.