Question SD card corrupting files?

articunobreeze

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So I'm not entirely sure, but I think my SanDisk 128gb micro SD card is corrupting the files stored on it. It's a brand new card, only took it out of the packaging and tried using it a few days ago. I was downloading a few things directly to it yesterday, which were stored in zip or 7z folders. After everything had downloaded and I started extracting them all, both winRAR and 7zip informed me that nearly half the folders had corrupt data. I initially assumed maybe it was the site I downloaded from, so I tried downloading the same files from elsewhere across 2 different sites, but some of those also corrupted.

I'm now assuming maybe it's my internet, it was a little spotty yesterday. I've never experienced anything like this before though, I've had failed downloads before but never corrupt ones, and they seemed perfectly fine after downloading until it came time to extract them. So I download them again today and all seems well and good after I test them in 7zip and winRAR, no errors found. But later on in the day when I have time to extract them, a handful of them are somehow corrupt again, even though I'm 100% certain they were returning no errors just hours earlier. The only change I made was that I did move some of them into a new folder after testing, but one file remained in the same location before and after extraction since yesterday, and is now apparently corrupt AFTER it's already been unzipped (according to 7zip, the file looks fine otherwise on windows explorer).

I'm at a loss now, I can only assume that somehow the SD is corrupting the files? In all my years of using computers and technology, I've never seen this before, fortunately have never had an SD card or HDD crap out on me yet, and I've never seen corrupt data like this before.

I don't believe it's fake, I have several of the same SD card I've bought from the same place, and I've had 2 different ones in use for 1-2 years now that have never had any issues. Also used another one just a few days ago, brand new, and had no issues. I've used H2testw and it has the correct amount of storage space, and I've tried writing and verifying it about 4-5 times with about 5-10gb of storage each time now and it isn't turning back any errors. I know I should ideally re-format it and test it, but I have yet to try that as I haven't had the time. I've also tried the standard error checking function on Windows for the SD card, but that doesn't find anything. The card is formatted as exFAT.

I would like to rule out any issues that are perhaps somehow on my end before I try returning the SD card. It's very bizarre and I honestly don't know what the issue could be. Are there any other tests I can perform the SD card to verify its integrity?
 
Where do you download them. On what kind of drive.

Where do you extract the files. On what drive or directly to the SD card?

Just test with another SD card.

If the files are corrupted when you extract them on your PC drives then it doesn't have anything to do with the SD card and it would be the drive in question or the source of those files.
 

articunobreeze

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Just download something to your hard drive and extract it from there and if it doesn’t corrupt then you know the SD card is probably bad
I did try downloading 5 different ZIP/7z files to my HDD and extracting them. No issues, but I'm not sure if that necessarily means anything because I downloaded about 10 or so to my SD card earlier, and only one corrupted itself later on in the day before extracting any of them (they were all fine beforehand though according to a winRAR test).

I will wait and see if any of the files, both the extracted ones and the zipped ones, "corrupt" themselves over the next few days.

Where do you download them. On what kind of drive.

Where do you extract the files. On what drive or directly to the SD card?

Just test with another SD card.

If the files are corrupted when you extract them on your PC drives then it doesn't have anything to do with the SD card and it would be the drive in question or the source of those files.
From Chrome, not using any kind of download manager. I'm downloading them directly to the SD card, which I have plugged into my computer via the adaptor that came with it, in the standard SD port.

Directly to the SD card.

I haven't had issues with other SD cards, but I have not tried downloading the exact same files to other ones recently, though I have downloaded similar files with no issues. I have tried downloading some of the same files directly to my HDD and extracting them, and have had no issues so far. I haven't ever had issues with these particular sites in general, and it seems very bizarre for 3 different sites that are unaffiliated with each other to all be having corrupt 7z/rar/zip folders. I suspect it likely is the SD card, but I'm not 100% certain, especially since it appears to be working and detecting fine otherwise and files don't appear as corrupt when just looking at them via windows explorer.

I'm going to try running a full write + verify with H2testw over night and see what the results are.
 
I did try downloading 5 different ZIP/7z files to my HDD and extracting them. No issues, but I'm not sure if that necessarily means anything because I downloaded about 10 or so to my SD card earlier, and only one corrupted itself later on in the day before extracting any of them (they were all fine beforehand though according to a winRAR test).

I will wait and see if any of the files, both the extracted ones and the zipped ones, "corrupt" themselves over the next few days.



From Chrome, not using any kind of download manager. I'm downloading them directly to the SD card, which I have plugged into my computer via the adaptor that came with it, in the standard SD port.

Directly to the SD card.

I haven't had issues with other SD cards, but I have not tried downloading the exact same files to other ones recently, though I have downloaded similar files with no issues. I have tried downloading some of the same files directly to my HDD and extracting them, and have had no issues so far. I haven't ever had issues with these particular sites in general, and it seems very bizarre for 3 different sites that are unaffiliated with each other to all be having corrupt 7z/rar/zip folders. I suspect it likely is the SD card, but I'm not 100% certain, especially since it appears to be working and detecting fine otherwise and files don't appear as corrupt when just looking at them via windows explorer.

I'm going to try running a full write + verify with H2testw over night and see what the results are.
(y)Let me know the results. Try another SD card next.
 

neojack

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you probably got scammed.

it's probaly a 1 gb card, with a modified controler that announces 128Gb
when you copy a file on it, it just rewrite over and over

https://photographylife.com/fake-memory-cards

It happens at least once to everyone. Happened to me a few years ago.
Even cards sold on amazon and BY amazon can sometimes get a counterfeit batch. All this stuff is made in china and if the right person is bribed at the right moment, a counterfeit shipment can replace a legit one.


Solution : buy from a retailer that allows for free returns with no fees +test all cards you buy ASAP after receiving them
 
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articunobreeze

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Jun 15, 2017
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you probably got scammed.

it's probaly a 1 gb card, with a modified controler that announces 128Gb
when you copy a file on it, it just rewrite over and over

https://photographylife.com/fake-memory-cards

It happens at least once to everyone. Happened to me a few years ago.
Even cards sold on amazon and BY amazon can sometimes get a counterfeit batch. All this stuff is made in china and if the right person is bribed at the right moment, a counterfeit shipment can replace a legit one.


Solution : buy from a retailer that allows for free returns with no fees +test all cards you buy ASAP after receiving them
I've heard of these fake SD cards before, and I've always been worried about ending up with one. As aforementioned, I've bought this exact same SD card from this retailer before (Base.com), and all previous 3 have had no issues so far. They are listed on Sandisk's/Western Digital's site as an official reseller/retailer of Sandisk products as well.

I have tried comparing it to fakes using various guides/videos that explain what to look out for, and comparing it to my other identical SD cards and their packaging, I think it's legit, but I realise it could just be a very, very convincing counterfeit.

I'll see what H2testw says when it's finally done verifying. Got a feeling I'm gonna need this card replaced anyway, but it would be nice to know if it is indeed counterfeit or not.
 

articunobreeze

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So just an update on this: I took out the SD card, and noticed a small piece of plastic on one of the contacts of the adaptor. Looks like the same colour as the SD card, I assume it flaked off during production or something. It flaked away easily enough, but I was wondering if this could cause issues? I'm now using a different adaptor just to rule that out.

H2testw didn't turn back a single error from its full write + verify test, seems it does actually have 119gb of free space on it, so I don't think it's fake/counterfeit. However, I'd imagine if the SD card was faulty, there'd be at least something on H2testw to show this? I did a few smaller tests with it again as well, and again, no errors.

I've tried copying over files to the SD card again and "playing around" with them by moving them between folders, since moving the files before often seem to be correlated to them corrupting after they initially tested out perfectly fine immediately after downloading. After testing them after moving them, they still appear fine according to 7zip. I'll try fiddling about with it a bit more, see if perhaps the files start corrupting again within the next week, and if so, return it.

Edit: Okay, so sadly, it is still corrupting files. I downloaded a few more 7z files to it earlier to test it some more. I unplugged my SD card and plugged it back in before testing, and 2 of the 7 new files I tested were corrupt. For the heck of it, I decided to copy these corrupt files over to my HDD and test them there, and they're still corrupt there as well. I re-downloaded them directly to my HDD and there's no issues.

The weird thing is, it is ONLY corrupting 7z/zip/rar files, at least so far. I thought it had corrupted an already unzipped file yesterday, but it turns out the file was not actually corrupt, just incomplete (7zip claimed the "data ended unexpectedly", turns out I needed another particular 7z file for that folder because it was in 2 parts)

One other thing I've noticed is that the write speed is a little slow. It's usually only around 15mbs/s, both when plugged directly into my PC's SD port and via a USB SD adapter. My other SD cards of the same brand and type (Sandisk Ultra SDXC) are usually faster than this.

I guess I'm looking at replacing it unfortunately, but I'm more just bothered by how weird this issue now than anything.
 
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articunobreeze

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Sorry to bump this, but on further tests, including with a brand new SanDisk 128gb micro SD card, it seems the issue is more likely related to the downloads in general.

I formatted the original SD card and did a full H2testw test of it. It came back perfectly fine. I decided to try out another new SD card I've had sitting around since April, I formatted it before anything else and did a full H2testw scan, no issues at all.

So I try downloading some files to it to test it out and what do you know, half of them are corrupt when I immediately test after downloading. I'm starting to think it might be the SD port on my computer, so I use an SD card USB adaptor, but files also corrupt on that when downloaded directly to it. I decide to test all 12 of the files by also downloading them directly to my HDD, where they had no issues once again.

I highly doubt 2 different SD cards are faulty, especially when they were both bought at different times, from different stores I believe, and they both pass H2testw perfectly fine. I don't know if the issue is perhaps how Chrome downloads files (haven't checked other browsers), SanDisk itself having issues with some 7z/zip files, or my computer itself, somehow (it's running Windows 10, but I doubt that matters). I did try downloading some 7z files to it directly on my old laptop as well (running Windows 8), and it actually didn't have any issues with corruption with the 6 files I tried, but I am unsure if this is simply a coincidence or not. I used the same SD USB adaptor.

I should note that the files I was downloading to the SD card were fairly large (200mb-1.5gb). Dunno if this has anything to do with it, pretty sure I've downloaded things just as large to the SD card in my phone before without ever having issues, but I don't know if perhaps Android just has better compatibility with SD cards.

At the very least, I'm glad the SD card is in fact probably fine. It's still a very bizarre issue, and I do have to assume it must have something to do with 7z/zip formats because I was downloading quite a bit to another SD card just a week ago, though the files were not zipped, and had no issues. Again, files already extracted or not zipped do not seem to corrupt.

If anyone ever finds this thread with similar issues to mine, all I can suggest is to not download anything directly to the SD card on your PC, especially 7z/zip files. Download to your HDD first, extract there and then copy them to the SD.
 
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