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Archive 2009 · CF Write Cycles

KPBara
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p.1 #1 · p.1 #1 · CF Write Cycles

I read that CF cards can be rewritten for at least 100,000 cycles. I am an amateur but seem to do frequent deletes due to bracketing, continuous shooting, etc. I also read that if you keep a card in the computer, the computer continually accesses the card, each access being equivalent to a write cycle.

Just wondering if others could share their experience on how long their cards (mine are Sandisk Extreme III) last under various kinds of use.

I use a 20D/40D and would also like to hear statistics on how many shutter counts they are good for in real use. Thanks.

Nov 22, 2009 at 12:19 PM

EB-1
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p.1 #2 · p.1 #2 · CF Write Cycles

KPBara wrote:
I also read that if you keep a card in the computer, the computer continually accesses the card, each access being equivalent to a write cycle.

That is odd. What writing are you seeing in the logs?

EBH

Nov 22, 2009 at 01:09 PM

KPBara
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p.1 #3 · p.1 #3 · CF Write Cycles

It's not my personal experience. I only read that the computer would continuously access the card, checking byte order, etc.

Nov 22, 2009 at 01:59 PM

EB-1
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p.1 #4 · p.1 #4 · CF Write Cycles

It's not the boot drive, so I still don't see why there would be any writes/erases. Reads don't affect longevity.

EBH

Nov 22, 2009 at 02:12 PM

KPBara
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p.1 #5 · p.1 #5 · CF Write Cycles

EBH, thanks. I would agree with you. Maybe the article I read applies to when you work on an image while it is still on the card.

In your experience have you had a lifetime issue with a CF?

Nov 22, 2009 at 02:29 PM

Ian.Dobinson
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p.1 #6 · p.1 #6 · CF Write Cycles

dont sandisk have a lifetime warranty? so if it crapped out before you were prepared to just through it away (ie to small/slow in the future) it would be replaced

Nov 22, 2009 at 02:32 PM

KPBara
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p.1 #7 · p.1 #7 · CF Write Cycles

Ian.Dobinson, I am worried about a CF failing while in use and losing all the photos taken that session.

Others with experience on how long CFs last?

Nov 23, 2009 at 04:11 PM

theMAGE
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p.1 #8 · p.1 #8 · CF Write Cycles

KPBara wrote:
It's not my personal experience. I only read that the computer would continuously access the card, checking byte order, etc.

Even if it would access the card, it would be read-only. There is no reason for the operating system to write to the card unless you tell it to.

Nov 23, 2009 at 04:33 PM

theMAGE
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p.1 #9 · p.1 #9 · CF Write Cycles

KPBara wrote:
Ian.Dobinson, I am worried about a CF failing while in use and losing all the photos taken that session.

Others with experience on how long CFs last?

I am using a Lexar 300x 4 GB for two and a half years now, and almost 30K photos (~8MB each, on a 30D) and I have had no problems with it whatsoever.

Nov 23, 2009 at 04:34 PM

runamuck
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p.1 #10 · p.1 #10 · CF Write Cycles

Murphy's Law, the "Fickle Finger of Fate" or just plain losing the card are far more likely than ever wearing them out. In fact, I can pretty much guarantee you will replace it with a bigger/faster card long before you wear it out.

Never have I seen anyone write about a card giving the message that it is worn out.

Nov 23, 2009 at 05:14 PM

alanwarp
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p.1 #11 · p.1 #11 · CF Write Cycles

I rounded these numbers off a bit, but lets say you can fit 300 RAW images from your 40D on a 4 GB card. Due to wear leveling done in the CF card, which randomizes where the data is written in memory to avoid the sectors at the beginning of the card wearing out first, I believe you'd have to write about 300 * 100,000 = 30,000,000 raw files to wear out your card.

This assumes the 100,000 number is correct.

Nov 23, 2009 at 05:31 PM

Andrew J
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p.1 #12 · p.1 #12 · CF Write Cycles

http://en.wikipedia.org/wiki/Wear_levelling

Nov 23, 2009 at 07:28 PM

KPBara
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p.1 #13 · p.1 #13 · CF Write Cycles

Andrew J, thanks for the reference.

alanwarp, I am not sure I follow your argument. Please correct me if I am wrong but I take one cycle to mean each time you delete and rewrite images, and not necessarily the entire card's content.

Regarding card in computer, I sometimes use DPP to make changes directly to images on the card. The article I read says that under this circumstance, the computer accesses the card continuously and each time is equivalent to a write cycle.

Nov 23, 2009 at 07:58 PM

alanwarp
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p.1 #14 · p.1 #14 · CF Write Cycles

KPBara wrote:
alanwarp, I am not sure I follow your argument. Please correct me if I am wrong but I take one cycle to mean each time you delete and rewrite images, and not necessarily the entire card's content.

You only write a small percentage of the cards memory with each picture taken. If that picture went to the same location in the card's memory every time you took it, the card would start wearing out around 100,000 pictures.

But that's not what happens, every time you take a picture it goes to a different location in card's memory due to wear-leveling built into the card. So the memory wears out evenly, it's like the card is rotating its tires.

Each block of memory can take 100,000 writes, but you only write a fraction of the blocks with each picture.

BTW, do you have a link to this article you keep referencing?

Nov 23, 2009 at 08:09 PM

OntheRez
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p.1 #15 · p.1 #15 · CF Write Cycles

KPBara,
Note that the article is talking about a half million write cycles not read. Also note that this number is a statistical estimate not an average based upon real experience. Also note that unlike hard drives and floppy drives nothing physical ever touches the CF card media. It is read and written with light. Also, when a card is read it only reads the VTOC (volume table of contents) and the appropriate places on the card. Finally look at alanwarp's rough numbers again. Even if he is off by an order of magnitude (he isn't), 30 million accesses is rather inconceivable. If you are losing sleep over this do the following: only put the card into the reader to dump image files to DPP or whatever you use; eject and format in camera; and set up a regular replacement card replacement system. You are far more likely to lose, step on, magnetize, leave in the sun, or just get plain tired of how small/old the card is than wear it out.

Nov 23, 2009 at 08:14 PM

KPBara
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p.1 #16 · p.1 #16 · CF Write Cycles

alanwarp wrote:
BTW, do you have a link to this article you keep referencing?

http://digital-photography-school.com/memory-cards-how-to-extend-their-life-and-keep-them-healthy

Nov 23, 2009 at 09:22 PM

Mike C.
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p.1 #17 · p.1 #17 · CF Write Cycles

KPBara wrote:

Ian.Dobinson, I am worried about a CF failing while in use and losing all the photos taken that session.

Simple, buy a 1 series body and backup to the SD card.

Mike

Nov 23, 2009 at 09:46 PM


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