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Memory cards,a warning.

Discussion in 'Computer Related Help & Discussion' started by swanseadave, Aug 16, 2017.

  1. EightBitTony

    EightBitTony Well-Known Member

    A few weeks ago I finally switched to RAW on the CF card and JPG on the SD card. This doesn't slow down the shot rate (RAW to both would), but it at least gives me a JPG if the CF card fails mid-use. It means I have to empty two cards whenever I take the RAWs off the camera, but it's not a huge deal of extra work.

    The original reason for not doing that (and I've been not doing it for a couple of years), was that I wanted to force myself to learn how to process the RAW files, and while I was getting RAW+JPG I was always tempted to store them both, and keep looking at the JPGs. So I turned off JPGs totally, and spent two years getting comfortable enough with RAW files that now when I get the RAWs off, I can just delete the JPGs without a second glance!
     
  2. Bazarchie

    Bazarchie Well-Known Member

    Not wishing to question your expertise but what makes you so categoric in your responses?
     
  3. EightBitTony

    EightBitTony Well-Known Member

    Depends which of my responses you mean :)
     
  4. Bazarchie

    Bazarchie Well-Known Member

    Post no 20
     
  5. Petrochemist

    Petrochemist Well-Known Member

    It's not a good idea to be constantly deleting single files if the remaining data is left on for long periods. Deleteing a few odd files will do little to confuse your FAT table, especially if there's loads of space left on the card. But if the data on the card is being transferred to back up on a regular basis I can't see this will be a problem for anyone.

    Keeping the contacts of the card protected is definitely a good idea, but the only card I've had damaged recently was actually from the case it came in (which didn't release it easily causing the cover to open up) it does still work but I don't trust it.

    I hardly ever reformat my cards (just transfer all the data off them) and have yet to notice any problems from doing this.
     
  6. GeoffR

    GeoffR Well-Known Member

    What's to discuss? I do most of this anyway except that I don't format after each shoot but when I am ready to reuse the card/s and, like Roger I do fill my cards, I just use them sequentially (Nikon D3 with two CF cards). What he doesn't say is that come cameras can only cope with 1000 images in a folder and will start a new folder for image 1001 so that means I don't use cards larger than 16GB. As long as the images aren't on a single card the D3 folder number changes every 10,000 images.
     
  7. P_Stoddart

    P_Stoddart Well-Known Member

    Knew most all of that already. LOL

    But I don't agree with using a card reader these days.

    I read from the camera instead, just as fast and saves taking card out. :)

    Also I figure if you can see the image on the back screen then the camera can clearly read the file it created. :)

    But it is a bit silly if a memory card cannot be used to full capacity, engineering is about meeting specs. :)

    So makes no sense for a designer to go "lets make it 32GB but whatever you do don't go above 20GB"? LOL

    I have tested all my memory card to FULL. No problem.

    In fact if I had a memory card that did not hold close to the size (they always give size without format so 32GB is around 30GB) that is said after formatting then I would not use it.
     
  8. EightBitTony

    EightBitTony Well-Known Member

    That makes no sense. Can you explain why you think that's the case?
     
  9. EightBitTony

    EightBitTony Well-Known Member

    A mix of experience, technical knowledge and reading.
     
  10. P_Stoddart

    P_Stoddart Well-Known Member

    Do you not know what happens to storage device if they delete and re-write?

    They fragment, where if you reformat all that is cleared away and the image counter will go back to zero if that option is selected.

    I would only delete if the image is clearly pants or I was getting low on space. Plus I would not waste my time review in the field. :)

    So if the storage has fragmentation it will slow down the writing of new data. Because the computer system will have to run through the FAT for empty blocks otherwise you would run out of memory earlier. :)

    And not formatting in the camera/device makes no sense at all LOL

    After all that is the system that will be writing the data so you want the memory lined up with it's file system. Surely? :)
     
    Last edited: Aug 17, 2017
  11. EightBitTony

    EightBitTony Well-Known Member

    Eh? Are you talking about hard disks with spinning platters and moving heads which have seek penalties for picking up data from different physical locations, or are you talking about true random access devices like compactflash storage where essentially, the time taken to read data is the same across the whole device.

    Those are behavioural things and I'm fine if people don't want to delete stuff, but telling people it's dangerous and will cause problems is just garbage.

    Given what's already been said about wear levelling, in what way do you imagine the FAT filesystem is actually contiguous blocks within the storage? And if it was, in what way do you think the lack of a seek penalty affects accessing that data? Also, I really don't understand what you're talking about in terms of memory. But anyway.

    I've already explained one instance where the camera specifically gets it wrong.

    I don't understand that - it's meaningless. Remember that a quick format simply empties the FAT table, it doesn't touch any data. Deleting a file simply empties the FAT table of that file's entries, it doesn't delete the data.
     
  12. PeteRob

    PeteRob Well-Known Member

    I can only imagine it is fragmentation that is a concern, like it is with hard-drives. This will mainly affect people who repearedly delete files to "make room" on a full card. If the card isn't backed up at all then that's not good practice. I'm poor at filing so I'm in the habit of downloading everything each day a camera is used then wiping the card. Usually using "delete all" but I format probably every 2-3 months.

    I've never tried defragmenting a camera memory card.
     
  13. EightBitTony

    EightBitTony Well-Known Member

    There a single instance where fragmentation can affect solid state devices, and it's if a single file needs to be spread over so many locations in the filesystem that the filesystem limits are breached (i.e. there's a limit on the number of individual fragments a file can be made up from). I've got no idea what those limits are or if they even exist in FAT. Otherwise, the performance of a solid state drive is not affected by the number of fragments a single file consumes.

    More over, the smallest size of object you can allocate is a block, JPGs are all roughly the same number of blocks, deleting a single JPG just frees up room for another single JPG so fragmentation at that level is a tiny risk.

    I think most of these concerns come from the early days of digital cameras, with badly implemented firmware.

    With any camera created in the last 10 years, on any solid state storage created in the last 10 years (if not longer), there is no risk to data by using the filesystem as it is intended, and adding and removing files at will. You don't have to worry about fragmentation, and you don't have to worry about performance loss.
     
  14. PeteRob

    PeteRob Well-Known Member

    that is comforting - so what is different with USB sticks? They are forever going bad on me.
     
  15. EightBitTony

    EightBitTony Well-Known Member

    Cheaper price point and hence, lower build quality (and less tolerant silicon wafer handling, etc.)

    Otherwise, they're the same technology at the base level (silicon NAND / flash memory and some kind of controller).
     
  16. Bazarchie

    Bazarchie Well-Known Member

    So a personal opinion rather than that of a technical expert we can rely on.
     
  17. Craig20264

    Craig20264 Well-Known Member

    Just reading through and it sounds like Tony knows what he's talking about to me. Do you have any technical knowledge to the contrary of his explanations? It certainly doesn't sound like 'a personal opinion'.
     
    EightBitTony likes this.
  18. PeteRob

    PeteRob Well-Known Member

    ditto
     
    EightBitTony likes this.
  19. Benchista

    Benchista Which Tyler

    Well it's certainly informed opinion at worst. There's a world of difference in quality of opinions between the informed and the uninformed or even the misinformed and/or misunderstood(sorry, Paul, that's you!). I'm certainly no expert on all of this, but I do know Tony's right about what he says about FAT32, about the non-sequential nature of flash storage, and about fragmentation. Given the very clear way he explains these and the other points, it's pretty clear to me he has a decent understanding of the subject. And whilst I don't wish to decry a genuine expert, remember that the so-called expert in this case was a Director of Marketing, for a card manufacturer, and is a photographer.... there's no evidence that he's actually a technical expert on memory cards whatsoever. He may be, but he offers no technical reasons for some of his advice. He doesn't explain how deleting individual files can scramble the FAT table, nor why filling a card causes performance issues.
    On the former, I believe he has half a point; if you only EVER delete pictures from the card and don't format, you can end up with lots and lots of additional folder info etc left over which eventually can cause issues, but if you delete a few pics and then carry on as normal, and format the card prior to re-use then I'm struggling to see how there can be an issue.
     
  20. EightBitTony

    EightBitTony Well-Known Member

    All my opinions are given free and worth as much as you paid for them. Just like the author of the blog in question.
     

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