# CF card health



## EOBeav (Mar 28, 2013)

I just got back from a trip to the Oregon coast, along with about 450 photos. There were two on my 16G SanDisk (90MB/s) CF card that seemed to be corrupted. They were right next to each other, and they were the only two taken at that particular time. Is this a sign that my CF card is failing, or just a glitch of some kind in that particular session? Is there a way to test these things? I understand these things can fail at any time (this one has had about 11k shots on it). Also, I format my card after every time that I download to the computer, rather than just deleting my files. Any advice you can give me is greatly appreciated.


----------



## Mt Spokane Photography (Mar 28, 2013)

EOBeav said:


> I just got back from a trip to the Oregon coast, along with about 450 photos. There were two on my 16G SanDisk (90MB/s) CF card that seemed to be corrupted. They were right next to each other, and they were the only two taken at that particular time. Is this a sign that my CF card is failing, or just a glitch of some kind in that particular session? Is there a way to test these things? I understand these things can fail at any time (this one has had about 11k shots on it). Also, I format my card after every time that I download to the computer, rather than just deleting my files. Any advice you can give me is greatly appreciated.


You can check and fix the card by doing a LOW LEVEL or full format. This must be done by a computer, the Camera does a high level format which cannot discover or fix card issues.
It is a fairly long process, allow a hour. Then format it in camera. If there are any bad sectors, they should be marked as bad on the card, and the format process will skip them.
It really should not be necessary on a CF card, but run it and see if any errors pop up. A Fullformat writes to every memory cell, so it finds bad ones.


----------



## EOBeav (Mar 28, 2013)

Thanks MSP. Weird, when I went back into Lightroom, those two photos were there, even though LR had told me it couldn't import them. So maybe things are ok after all. I'll run the full format, though.


----------



## Mt Spokane Photography (Mar 28, 2013)

EOBeav said:


> Thanks MSP. Weird, when I went back into Lightroom, those two photos were there, even though LR had told me it couldn't import them. So maybe things are ok after all. I'll run the full format, though.


I hope its ok. Its a good idea to do a low level format once every 10 or 20 usages of a CF card. A SD card needs them frequently, which is why its built into the camera.


----------



## RGF (Mar 30, 2013)

Mt Spokane Photography said:


> EOBeav said:
> 
> 
> > I just got back from a trip to the Oregon coast, along with about 450 photos. There were two on my 16G SanDisk (90MB/s) CF card that seemed to be corrupted. They were right next to each other, and they were the only two taken at that particular time. Is this a sign that my CF card is failing, or just a glitch of some kind in that particular session? Is there a way to test these things? I understand these things can fail at any time (this one has had about 11k shots on it). Also, I format my card after every time that I download to the computer, rather than just deleting my files. Any advice you can give me is greatly appreciated.
> ...



On a PC just format the card - not a quick format? Any thing else? I had never heard about this so it great to find out about it


----------



## Mt Spokane Photography (Mar 30, 2013)

RGF said:


> On a PC just format the card - not a quick format? Any thing else? I had never heard about this so it great to find out about it


 
That's right.

Your camera does a quick format, meaning it changes the fat tables to indicate the card is empty and available to be overwritten. Same for quick format on a computer. That's why it is so fast.

On the other hand, a full format is very slow because it writes to each memory cell inserting a 0 or a 1. This is not the same as the original meaning of a low level format, its more of a erase function.

I use Lexar image rescue 4, which does a erase and then a format. Its a long process for a large card.


----------



## amarelux (Mar 30, 2013)

I purchased a Kindle book called Canon 5D Mark III Experience - The Still Photography Guide to Operation and Image Creation with the Canon EOS 5D Mark III written by Douglas Klostermann. The author claims that repeated low level formatting will degrade a memory card quicker than regular formatting.


----------



## pwp (Mar 31, 2013)

Lucky me, never lost a card in 13 years of heavy daily use. However, I do follow a few rules. 

1. I always format in the camera I'm going to use it in. 
2. I never delete images off the card "in camera"
3. I never expose the cards to strong fields...meaning I don't put used cards in a pocket with a phone.
4. I replace the cards after 18-24 months. 
This may be overkill but my career and professional reputation didn't come cheap. Cards are cheap.
5. I don't drop the cards.
6. I never use the cards in different devices. Canon EOS cameras only.
7. Download the images with a card reader, then extract it. Left in the computer it will continuously access the directory, checking the byte order, to see if there are any changes etc. This action is identical to a write cycle so the life of your card may be reduced.
8. Don’t work on the image while it’s still on the card. You could possibly reduce the life expectancy of the card just by doing that with a single image.
9. Some say it's good practice not to fill a card completely. I've never really worried about it. But it's true for a DVD burn or pushing HDD capacity to the limit.

Half of this might well be pointless mumbo-jumbo, but which half? Who knows...it's worked for me. 

-PW


----------



## curtisnull (Mar 31, 2013)

pwp said:


> Lucky me, never lost a card in 13 years of heavy daily use. However, I do follow a few rules.
> 
> 1. I always format in the camera I'm going to use it in.
> 2. I never delete images off the card "in camera"
> ...



I agree with pwp 100% on this one. I have been shooting digital professionally now for about 12 years and have followed these same practices. I have never had an issue.


----------



## jonathan7007 (Mar 31, 2013)

PWP's advice is excellent and that "avoid fields" advice seems like an extra good idea. Phones kill credit cards, too, when they roll around together in a pocket.

I asked a similar question here -- about how to determine the health of a CF -- a couple of weeks ago because it looked like I had a bad card, a Lexar 400x 64Gig CF unit. I got one interesting piece of advice: run chkdsk on the card. (Windows low-level diagnostic for drives...) I did not try it as it was clear there was an issue -- although hard to reproduce -- and Amazon replaced it right away. 

Lexar had almost no advice... sad, really. I did talk to them about how to determine that it was not a counterfeit (it wasn't). But that's not at play for the OP.


----------



## Lgrant (Mar 31, 2013)

I have been Lexar since the beginning of time. I have many that I have been using for nearly 6 years and not one has ever failed me, I always format from the camera.


----------



## Orangutan (Mar 31, 2013)

PWP's advice is thoughtful, but definitely overkill. Last time I checked, high-quality flash cards were rated for at least 100,000 write-erase cycles. Suppose it's just 1% of that; you'll have 1,000 uses of that card before it's worn out. That's almost 3 years of using it every day, at 1% of rated life.

>format in the camera I'm going to use it in
Yes, this is a good idea.

>never delete images off the card "in camera"
Me too, but not because of wear on the card; I do this because I don't want to accidentally erase the wrong image and/or I've got better things to do with a camera in my hand.

>never expose the cards to strong fields...meaning I don't put used cards in a pocket with a phone.
This is very unlikely. Flash memory is very robust, even able to survive x-ray machines just fine. If there's contrary evidence I'd appreciate seeing a reference.

>replace the cards after 18-24 months. 
Overkill, as described above. Replace them when you need a bigger/faster card, or if you develop distrust for your card. 

>I don't drop the cards.
Not dropping stuff is generally a good plan. They're tough, but if you treat them like glass you won't accidentally drop them down a storm sewer either. 

>never use the cards in different devices. Canon EOS cameras only.
Overkill. So long as you reformat when you put it back in the camera, you're fine. If you tend to be forgetful about such things, then maybe you shouldn't use it in other devices.

>Download the images with a card reader, then extract it. Left in the computer it will continuously access the
>directory, checking the byte order, to see if there are any changes etc. This action is identical to a write cycle
> so the life of your card may be reduced.
This may have been true in the early days, but I'd be surprised (very surprised) if modern OS's aren't smart enough to avoid this. The best reason to pull it out right away is to make sure it gets back in your camera bag before you go out for a shoot.

>Don’t work on the image while it’s still on the card. You could possibly reduce the life expectancy
> of the card just by doing that with a single image.
Again, this is unlikely with modern wear-leveling algorithms. There's a better reason not to edit in-camera: the old adage "always make a backup of your original, and work only on copies." If you bork the image in-camera, it stays borked.

>Some say it's good practice not to fill a card completely.
I can see this somewhat: because file-size can vary quite a bit, you don't want to have the most recent image fail to save due to insufficient remaining space. It wouldn't cause the card itself to fail, just fail saving the image. Sure, pull the card out when you get to single-digit space remaining.

And again, my standard advice: "test, don't trust." Test new cards thoroughly before you use them. http://www.canonrumors.com/forum/index.php?topic=13413.msg241802#msg241802


----------



## pwp (Mar 31, 2013)

Orangutan said:


> PWP's advice is thoughtful, but definitely overkill....


Yes I alluded to the fact that it was probably half mumbo-jumbo. Hah! These harmless habits were established at the dawn of time and hey, none of them are time wasters. But I'm sure you're right, what was good practice at the turn of the Millennium may have been overtaken by OS smarts. That's a good thing.

-PW


----------



## hgraf (Mar 31, 2013)

pwp said:


> Lucky me, never lost a card in 13 years of heavy daily use. However, I do follow a few rules.
> 
> 7. Download the images with a card reader, then extract it. Left in the computer it will continuously access the directory, checking the byte order, to see if there are any changes etc. This action is identical to a write cycle so the life of your card may be reduced.
> Half of this might well be pointless mumbo-jumbo, but which half? Who knows...it's worked for me.
> ...



FWIW this is not true. 

Flash technology is not affected by reads. What you are describing is NOT identical to a write cycle. 

On top of that, the OS assumes that mass storage devices DO NOT CHANGE by themselves (I know this since I've designed hardware that emulates a MSD with changing contents), as a result, the OS isn't going to "check" on the card if it hasn't changed the card. 

Only way to get the OS to do another read (of the FAT, or whatever) is to exhaust the OS cache of the volume, which depending on OS ranges from a few MBs to hundreds of MBs. In any case, this won't affect card life since it still won't be a read.

TTYL


----------



## hgraf (Mar 31, 2013)

Mt Spokane Photography said:


> You can check and fix the card by doing a LOW LEVEL or full format. This must be done by a computer, the Camera does a high level format which cannot discover or fix card issues.
> It is a fairly long process, allow a hour. Then format it in camera. If there are any bad sectors, they should be marked as bad on the card, and the format process will skip them.
> It really should not be necessary on a CF card, but run it and see if any errors pop up. A Fullformat writes to every memory cell, so it finds bad ones.



A "low level" format is very different from a full format, and actually isn't even applicable to flash technology. I won't go into the details here, here is a link:
http://en.wikipedia.org/wiki/Disk_formatting#Low-level_formatting_.28LLF.29_of_hard_disks

As for a full format, you are correct, it will write every location and make sure it reads back OK. What I will mention is if your CF card reports ONE bad sector, throw it out.

Flash cards are very different from hard disks. On them it was normal for a bad sector to crop up every now and then (it's not normal anymore for the user to see a bad sector since a modern hard drive has spare sectors that it maps in to "fix" bad sectors. If the user sees a bad sector it means the drive has run out of spare sectors. That is bad, replace the drive immediately if you see that).

On a flash card a bad sector means the card is likely very close to failing completely. With how cheap cards are these days I wouldn't trust a card reporting a bad sector for one second.

TTYL


----------

