Format or Erase Cards Before a New Shoot?

[Brad_]

>>> I don't mean adding a new hard drive and memory to your PC. I mean DESIGNED, from the ground

up, product specification, component selection, interface design, printed circuit board layout, power supply

specs, noise analysis, etc? I'll hazard a guess based on your preceding comments... ZERO. I've

designed over fifty complete products, as defined above, and subsystems for many others. ...

 

Since my views are in total alignment with Jeff's, I'll respond. While that's a nice bit of chest-beating, the above has absolutely nothing to do with

challenging the notion that simply erasing files from a card is in any way inferior to a total reformat. Period.

[leighb]

<p>Well, Brad,</p>

<p>Jeff has taken it upon himself to claim that the instructions in the manuals are wrong.</p>

<p>This implies an in-depth and highly detailed knowledge of the product designs, which I believe he is incapable of understanding even if he managed to obtain them.</p>

<p>He appears to be claiming expertise in an area with which he is actually unfamiliar.</p>

<p>Presenting credentials is not "chest beating", merely clarification.</p>

<p>- Leigh</p>

[Brad_]

>>> Jeff has taken it upon himself to claim that the instructions in the manuals are wrong.

 

No, he didn't say that. You are inferring. Nevertheless, I'm in total agreement with what he asserted.

[Ed_Ingold]

<p>Jeff said, "<em>Nobody ever presents evidence of what has happened without formatting</em>."</p>

<p>What kind of evidence are you asking for, golden tablets (sorry, Joseph Smith got the last of those, then lost them)? Testimony is evidence too (q.v., any courtroom drama or Tru TV). I've actually experienced the things I mentioned in my last post.</p>

<p>My D1x had a propensity to change directories without any discernible cause. My D2x did that on at least one occasion. Unless you opt to "see all directories", only the most current directory will appear in the viewer, and you can only erase the images you can see. Like others, I have tried to add photos to the CF card with a computer to view them on the camera. It never works, and nothing you add is visible in the viewer regardless of the menu settings. If you actually write to the card, the computer can add hidden information, such as a "recycle" directory.</p>

<p>A soft format doesn't erase the FAT (file allocation table), it replaces the records to indicate that the corresponding sector is available. The actual data is untouched. When you "erase" a file using the viewer or file utility, only the first entry in the FAT is replaced, leaving the other FAT records and sector data untouched. If this is confusing, there may be references from the 80's which describe how a FAT works.</p>

[josh_wolf]

<p>I have a Canon PowerShot SD400. I found out that if I only delete files after shooting video, then the capacity of the SD card is drastically reduced when I shoot video the next time. (This problem does not happen when shooting stills.) If I format the card, this problem does not occur. The SD400 is quite old, so perhaps this is no longer a problem in newer models.</p>

[Matt Laur]

<p>The act of erasing a file is simply an update to the FAT (file allocation table). This is the index system that knows where every file (and every piece of every file) is on the storage device. If the FAT is corrupted in some way (say, by prematurely removing the storage device during a write), you're still leaving some wreckage on the storage device. Erasing files doesn't fix this. When you format the device, you're creating a fresh, <em>new</em> FAT. This is a very important distinction.<br /><br />As for formatting the storage device in-camera (vs. using an outside device, like a computer) ... well, if nothing else, it's just faster to do it in the camera. The camera is also (virtually) incapable of introducing malware onto the device, whereas a computer absolutely can. Formatting in-camera scrubs the card in a very predictable way. Formatting externally introduces more variables into the situation. Just erasing files, even more variables.</p>

[Spearhead]

<p>Nobody has presented any evidence that there is any difference between erasing and formatting in the camera in terms of performance, longevity, etc. None. There's a lot of talk, but nothing has been presented. FWIW, camera manuals don't present any either. Unless someone can come up with something concrete, it's all just talk without any real value. If there's a difference, there is data.</p>

<p>The problem with "evidence" here is that this is something that can either be scientifically proven or it can't. This means statistical data, not "gee it happened to me once." I've got lots of stories about things that "happened to me once" and often found a cause later that had nothing to do with what I thought was happening. If there is a difference, it can be proven in controlled testing with documented data. This data doesn't exist anywhere as far as I can see from this thread, so it's just useless chatter.</p>

[leighb]

<blockquote>

<p>If there is a difference, it can be proven in controlled testing with documented data.</p>

</blockquote>

<p>Absolutely untrue. Spoken like true armchair engineer.</p>

<p>Define please "controlled testing". There are a hundred different parameters that affect memory performance, any one of which can cause data corruption during write or read cycles. </p>

<p>The first and most obvious problem is that if you read back corrupted data, you don't know if the memory contents is wrong, or if the read function returned data that differs from the memory contents. How would you propose distinguishing between those two scenarios?</p>

<p>There have historically been some very odd sensitivities in memories. For example, "pattern sensitivity", in which writing a particular bit pattern to a particular address, possibly dependent on the content of adjacent memory cells, can cause data corruption occasionally, maybe once in 100, or 10, or 1000 times.</p>

<p>Electronics don't work the way you read in books. That's only theory. Making real circuits work in the real world is experience.</p>

<p>Jeff, you have no clue what you're talking about. Why don't you quit wasting everybody's time?</p>

<p>- Leigh</p>

<p> </p>

[Matt Laur]

It's easy, Jeff. Corrupt the FAT on a card (or on any storage device with a file system). There are many ways to do this,

and people do it all the time. We hear about it in these forums like clockwork. Now, erase files from the file system, and

write critical files back to it. Comfortable? You shouldn't be. The FAT will not become uncorrupted by deleting files. You

either need to fix it with speciality software, or reformat the device to give it a fresh file system. Unless your contention is

that corrupted file systems don't happen, then that's really all there is to it.

[Stock-Photos]

<p>Tom Thumbnail, in my opinion, and for the sake of back-up, it's better to wait until a card is nearly full before erasing. I erase images and very rarely format a memory card.</p>

[Ed_Ingold]

<p>Jeff,</p>

<p>Experiment 1: Write something (e.g., an image) to a CF card with a computer while it is attached to a card reader, then try to erase it in the camera (hint: the camera won't see it even in a directory set up by the camera, hence can't erase it).</p>

<p>Experiment 2: Create a new image directory using your camera's menu and shoot some pictures. By default, the camera will only see images in the current directory. If you do not elect to display "All directories" using the menu, you cannot erase anything in older directories.</p>

<p>Experiment 3: Format a card (in the camera) and check the fragmentation level using a card reader and a computer. Shoot a couple dozen images, erase them in the camera, then shoot some more images. Recheck the fragmentation level and notice that it has increased. FAT disks are particularly sensitive to fragmentation, which will degrade the performance of the card and can lead to corruption of the file system (mainly cross-linking).</p>

<p>You clearly have no concept how a disk (or CF) file system works. If these experiments pique your curiousity, try to find a basic primer on disk operating systems. This would be more providential than mocking something you don't understand.</p>

[kendall helmstetter gelner]

<p>"Nobody has presented any evidence that there is any difference between erasing and formatting in the camera in terms of performance, longevity, etc. None"</p>

<p>Well actually one person presented a direct real-world example, and you dismissed him out of hand. So you are obviously simply a troll and I'd advise others against responding to anything you write, I know I'll ignore whatever personal attack you offer in response to my post.</p>

<p>However, I felt I should add one other aspect that makes formatting a better choice - less wear on the SD card.</p>

<p>Deleting all images goes through one image at a time, removng the image and in the process re-writing the FAT each time, and also in some case zeroing out images (depends on what is doing the delete).</p>

<p>You can tell there are more writes to the card during this process simply by observing that it takes much longer to delete all images from a card than formatting.</p>

<p>From there, you only have to add in the simple fact that all flash media has a limited write lifespan, so the more writes you are doing, the faster you are wearing out the card to the point in the future when some of the capacity will be lost of the card will die outright (which I have had happen with a few SD and CF cards). Even if you ignore the fact it's safer to put in a new FAT table (yes I know table is redundant), it's quicker to format than to delete, and manuals generally to direct you to format cards - even ignoring all that, it's better just from the standpoint of the lifespan of your media.</p>

<p>Anyone may feel free to disagree, if they wish to throw physics and common sense out the window.</p>

 

[jcuknz]

<p>This is an old question if you have bothered to read this far down the thread :-)<br>

I have only formatted once when I thought I had problems with a long gone card.<br>

Using Windows I first copy files to my 'archive' second hard drive. Then I move the files to appropriate 'working' folders on primary HD. This appears to empty the card.<br>

Examining the 'properties' of my cards over a period of time I have found a very small, relative to card capacity, build up of junk on CF cards and none on SD's. The build-up amounts to less than one file and since card capacity varies with subject matter it seems to me of no matter.<br>

This of course is very subjective opinion based on empiracle rather than science :-)</p>