In multiple cameras (Leica S2 with CompactFlash, Leica M9 with SDHC, Nikon D3x with CompactFlash), I have been losing (corrupting) image files every so often, perhaps every 300 or 400 images.
These are top-of-the-line authentic SanDisk Extreme Pro cards.
The two 64GB Extreme Pro CF cards were replaced last fall with new ones by SanDisk when I had multiple serious failures in the Leica S2. But the replacements still have sporadic issues.
When the problem first occurred, I tried two SanDisk Extreme Pro card readers (one brand new) with two different cables on three different Macs. Same behavior with all combinations.
Some of the failures are pure data corruption; the file sizes are correct but the files cannot be opened by ACR. Some corruption is the JPEG preview only. But many have been truncated files, including some of zero bytes and others of intermediate size; this is true on the original card, not just after copying to the computer.
Nick M writes
I always use a Mac with the SanDisk Extreme card reader (hey, SanDisk cards in SanDisk readers ought to be golden), Nick apparently uses Windows.
I just read your post about SanDisk card corruption. I have experienced similar issues - see the attached jpegs produced from the original raw files. The file 006 is as viewed in Preview, the 006-2 is as the file appears in Lightroom. I have countless other examples - in some downloads up to 10% of files are impacted.
Initially I thought it was an issue with the downloading software I use - Downloader Pro run in XP under Parallels. I contacted Chris Breeze who told me it was almost certainly a hardware compatibility issue, possibly my card reader (see attached email). I use a SanDisk Firewire Extreme reader (mid 2010), on your recommendation if I recall! After some experimentation, I found the following:
- Sometimes the raw files would initially show as corrupted (similar to my attached files or yours) when the thumbnails were drawn in Lightroom, but when previewed at 100% in Lightroom the problem would go away - this occurred in a minority of cases
- Sometimes the file would be problematic in Lightroom, but would be OK in Preview - again a minority of cases
- Generally, if I went back to the card and viewed the file directly from the card or copied the original raw image from the card with a simple drag and drop the problem disappeared
- I tried downloading with an older USB card reader and I still experienced problems, but not always with the same raw files
- I tried a second identical SanDisk Firewire reader and the problem vanished
- With the 'good' FireWire reader I tested my usual process of using Downloader Pro to download to my hard drive (not yet a SSD) and backup to an external drive as part of the process. Generally I use an OWC FW800 drive. This worked 100%. Then I tried using a USB external drive. In this instance, 100% of the files on my hard drive were OK and around 5% of the 'identical' files on the USB drive were corrupted.
Given the above, particularly the latter 2 points, I was pretty sure the problem was with some combination of the reader and the Mac and not the card itself. This is where I am at now - using the FireWire reader and FireWire external drive seems to work flawlessly. But I remain nervous and this is clearly not a satisfactory solution. It almost seems as if there is an overload to the data throughput (or a bottleneck) under some scenarios somewhere in the Mac? I am not qualified to say or figure it out. Ironically, I did think of reaching out to you a couple of months ago about this, but once I had a solution that was working I didn't. I was pretty sure you would be the guy to figure it out, but didn't think I would be able to explain the problem clearly or have it recur with you!!
I am using a MacBook Pro (5.4) with 8Gb of memory. I also have an old Mac Pro on which I only did limited testing and my memory is a bit hazy on the results. I had not experienced the problem on the Mac Pro, but had been using the 'good' reader and was not backing up to an external drive as part of the process (instead backing up with a FW800 time machine drive). Hence, the Mac Pro had, largely by chance, been operating under the same conditions that work on the Macbook Pro. I think I tested the 'faulty' reader on the Mac Pro and had a recurrence of the problem, but would have to test that again to be sure - I can do so in need.
DIGLLOYD: I had no such luck— when I had the trouble, the bad files were bad on any computer I tried. Truncated files are gone for good.
Rob S writes:
Another data point, for whatever it's worth: I bought an 8GB Extreme Pro card from B&H to use with my D7000 (SDHC), and it occasionally throws a read error in the camera. So far just removing and reinserting it have remedied the problem, and I've seen no image corruption, but it still makes me a little nervous, especially now with your report.
DIGLLOYD: Could this simply be a bad connection to the card? I’d be cautious with such a card and personally would exchange it.
John S writes:
Have you tried using a USB reader with the same card that shows the corrupted RAW image? I assume you are downloading with a FW800 reader... I have seem a few comments on this odd corruption using FW readers of various brands. I get it on occasion with Lexar cards as well in both the old Sandisk 800 reader and the Lexar stackable 800 readers...
One difference is I get a corrupt area about 1/4 the size of what you have shown and it can vary on its placement in the image.
DIGLLOYD: I have not tried using a USB reader. They are unacceptably slow. And truncated files are not going to untruncate themselves and would not read in the camera either. But in the future perhaps I will try on examples like the one I show above, just as a data point.