Do flash cards write more slowly as they get older? I have some compact flash cards that are around 4-5 years old. I could swear that my camera used to write to the cards faster than it seems to now.

I've had flash cards from 1996 to the present, and still have many old ones, and what I noticed is the slowdown soon after writing to the card many times. But that's short-term - after the initial slowing they didn't get any slower. If you format the card with the camera, it should write at a predictable rate. There's an older topic here on the LL forum describing many technical details, but my actual experience tells me you should get the same performance in year 3 as you did at the end of year one and two.

Thanks for the reply.

My impressions on how fast the camera should write the pics to the card are based on when the camera(20D) was new and it worked so much faster than my previous camera(Fuji S2). I don't do a whole lot of rapid fire shooting, but it seems that in the last year and a half or so, I've found myself waiting on the buffer to write out a lot more often than I used to.

My guess is that all things being equal, the performance shouldn't change. There's no moving parts and if your batteries are fresh I'm guessing the same amount of electrical power is going to the card and whatever writes to it. Perhaps one's expectations get faster?

Consider also that newer cards have become much faster and perhaps your expectations have changed (in regard to performance).

I suppose if you have been deleting pictures rather than reformatting the card you are dealing with fragmentation on the card.
If your camera gives you the option of "format" or "deep format" I would do a deep format. You could also check out the file structure (FAT, FAT32?) and do a deep format on the computer making sure that you have the proper structure selected; then do a format in the camera.

I’ve used these cards with this camera for five years, and I think that I have a pretty good feel for it’s capabilities. It may just be my expectations though. Nothing is ever fast enough.

As far as formatting goes, I usually reformat cards to clear pictures, especially if the card is full. If I only have a few pics on the card I might just delete them without reformatting. I’ve reformatted the cards on the computer a few times, and I’ve zeroed them out a few times.

I need some more cards anyway. I guess that I’ll just relegate the older cards to backup duty.

Well, the problem is: flash cards are ageing !

This is an inherent problem with Flash. You can look all this up on wikipedia, but in short: There are more or less two types of flash: NOR and NAND. NOR has a possible 100.000 - 1.000.000 write cycles before it gives up, NAND had historically less possible write cycles, but is catching up lately. All fast CF cards are based on NAND Flash (NOR is sloow, but has other advantages, e.g. processors can boot from it directly). The CF Card controller is tracking how often it wrote to a flash sector and tries to level the wear of the sectors. This is called wear levelling. The DOS file system doesn't notice which physical sector it wrote to, the CF card controller shifts the same logical sector to a new physical sector the next time the FS writes to it. If the CF card Flash reaches its life time limit, the card will flag more and more sectors defective and has more work to do to find the good ones, also fragmentation will get more of a problem.

Fragmentation in combination with a full Flash is always very bad. If a write request cannot be fulfilled within one sector, but has to be shared among several flash sectors that already contain other data, the following happens: the first sector containing free space is read into the internal CF card buffer, the part that was free is then filled with part of the data which has to be written to the card and then the CF card needs a free sector to write the sector as a whole to a new place on the card. This goes on with the next sectors until all data has been written.
This process is necessary because Flash sectors cannot be written byte wise like RAM but only sector wise. To be precise: the sector cannot simply be written, it has to be erased first and is then "programmed". The wear levelling causes the CF controller to use a new sector which gets slow if the file system is full and fragmented as the CF card controller has to shuffle around the data to make free space ...

BTW look, if the capacity of your card is starting to decrease. That's a good hint for end of lifetime ...

The lifetime of CF cards is quite dependend on the type and brand. E.g. STEC industrial grade CF cards are specified up to ~2.000.000 write cycles or the equal of 10 -15 years of use. Current industrial grade cards even contain an internal condensator to buffer the last write operation to the flash, in case the CF card is removed from its slot before completion. The internal controller logic is the key for reliability of a CF card. I guess the newer ones are much better than the ones you could get 4 years ago.


Regards,

Daniel.

Wow! I really learned something here. Thank you.

A few comments on these excerpts:

The aging theory (or fact) just isn't relevant for most users. Yes, if you use the card as a write-to drive from your computer, with heavy read-write every day, but no if you use a reliable brand like Sandisk, with your camera. Cameras don't put anywhere near the wear on CF cards that a computer can if used as a write-to drive.

Wear leveling is discussed in good detail in the LL forum thread on SSD's (solid state drives).

From a DOS/FAT file system perspective, fragmentation would be a problem if you were in the field and took a lot of photos and deleted many of those files in between shooting, in combination with not having a lot of extra space on the card. It's best to either not delete while shooting, or if you do, use cards that have a lot of extra capacity. I use 16 gb and 32 gb cards currently.

I have never noted capacity decreasing on any flash cards I've had. And I've had most of them, some used as write-to drives from computers.