2) Cheap cards sourced directly from China are usually fake and will fail a format test. I tried multiple times and could never find a reliable source.
3) MS Bitlocker is a security measure that also seems to serve as a reliability test. Cards with physical memory reliability issues seem more prone to write failures with Bitlocker. It's better to know about this up front.
4) If your data is really important, always make a backup copy of any card.
5) Physically, microSD cards are fairly durable and even water resistant thanks to being encased in epoxy.
I have one on my watch strap and take it wherever I go, even the shower and pool. Just make sure it is dry before plugging it in.
You can buy genuinely reliable microSD cards, if you really need them. Delkin, Innodisk, Swissbit and others make industrial microSD cards with SLC flash, ECC, SMART and power loss protection. Capacities are small and you'll pay a steep premium, but they legitimately have endurance and MTBFs that compete with conventional SSDs.
You can get "industrial" versions of these cards that are intended to be used as BOM items for products. This means you get a stable supply and they won't change the part number out from under you (which happens even with reputable suppliers when you buy as a consumer). When they're about to EOL the part, you get a heads-up multiple months in advance and a "last time buy" opportunity.
In my experience, these aren't "better" performance-wise. You just "know" what you're getting, have an opportunity to qualify it, and you won't get surprise changes.
Of course, the price is jacked up as a result.
Generally speaking, it's usually better to make the customer responsible for the SD card if you have to use one at all.
Ref 2: if you buy from Amazon, you never know if you get a genuine card. Even if you shop from an official seller, as inventory is commingled so you might as well get a fake one from another seller with the same SKU.
Big problem in action cam related circles, where lots of people have broken recordings due to fake cards.
if you buy from Amazon, you never know if you get a genuine card.
Yes, but there is a significant difference --- I can always return it to Amazon postage free if the capacity is fake and it won't format properly. Presumably, Amazon extracts the appropriate weight in flesh from the seller.
The way retail typically works in the USA, the vendor assumes all the risk --- any problems get unrolled backwards. You can sell a fake product on Amazon --- but it will likely cost you --- not Amazon (who controls the money) nor the end consumer if he is astute.
If there are too many returns, the machine doesn't get fed; it gets punished.
Amazon and other retailers have played this game for a very long time and they aren't in it to lose money.
In my experience, the thing most commonly faked with memory cards is the capacity --- for example, an 8Gb card altered to appear 64Gb, until it is formatted.
If you want extra assurance, buy Amazon branded cards. In this case, Amazon assumes almost all the risk so there is little incentive for fakery.
> If there are too many returns, the machine doesn't get fed; it gets punished.
On Amazon? I highly doubt it. The threshold for “too many returns” is probably rarely hit. MicroSD’s are super cheap - people don’t return things that are cheap because they don’t consider it worth their time. Then these companies go and pay people for good reviews and just keep flipping inconsistent/garbage products.
If punishment were a real thing that companies had to deal with then this wouldn’t continue to be a problem. It’s been this way for many, many years. Amazon has no equal competitor, there’s nowhere else for folks to go and people rarely look at the specific vendor they’re buying from. As far as they’re concerned it’s all Amazon.
> Amazon has no equal competitor, there’s nowhere else for folks to go and people rarely look at the specific vendor they’re buying from.
I’ve bought more off target.com than Amazon and I read at least one other commenter here who does the same. Walmart.com also has a wide range of products.
Amazon back charges the vendor for every return --- which likely includes return shipping and handling. I can assure you, Amazon doesn't just "eat" these costs.
Remember, Amazon holds the cash for all sales. The cost of returns is extracted from vendor disbursements. A fake card sold for $10 may cost the vendor $20 if it gets returned.
If enough people return the item which again, with microsd cards, is likely not nearly often enough on Amazon.
If “the system worked” i.e. companies get appropriately punished for selling bad products, then this issue wouldn’t still be so widespread. It’s basically a feature of Amazon now. People just assume they’re going to randomly get junk. It’s baked into our expectations at this point.
Personally I found an easy way to tell - write a script which fills the drive fully with random data (computing a check sum as it writes), then read it all back and verify you get the right checksum.
Oh and compute read/write times while doing so.
If the read back data doesn’t validate, or you can’t write the amount expected, or the read/write rates don’t match expected? faaaaaaake
Pretty accurate too. I personally never had an actual fake Sandisk SD card from Amazon. I bought probably 50 of them in the space of 6 months at one point. Other brands were not great.
USB flash drives though? Literally all trash. I tried at least 5 different ones before I just gave up.
Are you saying that the counterfeiting of name brand packaging is so skillful that even careful inspection by us the consumers cannot reasonably hope to detect it?
“One vendor in particular interested me; it was literally a mom, pop and one young child sitting in a small stall of the mobile phone market, and they were busily slapping dozens of non-Kingston marked cards into Kingston retail packaging. They had no desire to sell to me, but I was persistent; this card interested me in particular because it also had the broken “D” logo but no Kingston marking.”
Important thing you should be aware of: not all counterfeit cards fail a format/f3 test.
I recently bought a very expensive Sandisk Extreme UHS-II V90 card from Amazon. It passed without any issue when doing a full capacity check, but was still fake because they were using slower (150mb/s vs 300mb/s) flash.
The average user[0] would never know, because it was definitely “faster” than other cards and maxed out the UHS-I reader in my MacBook Pro. I returned it and bought from my local camera store (Henry’s) and the performance difference was very obvious.
[0]: I guess you could argue that the average user wouldn’t be buying a $200 V90 card, but I still think you could fall victim to this if you didn’t explicitly own a dedicated UHS-II reader.
1) I have ~7 cards (all from China and Sandisk, solely because Sandisk has a website where you can verify the card is genuine) that are in daily 24/7 use for 6-8 years with no issues (mounted in rw mode)
2) ...
4) that's true for any storage media
If you ever tried running uSD card in SDR104 mode, you'd notice that they tend to heat up way more than in lower speed interface modes. So for longetivity, I guess it's better to run them at HS mode (which is just 50MHz), or at least lower the SDR104 bus frequency from 200MHz to something lower.
Write pseudorandom data to the whole card with a fixed seed.
Read back data and compare against the same pseudorandom data with a same fixed seed.
Or just make a random data file the size of SD card and write/read back compare, if you don't care about having to store the big file and also testing for potential local disk corruption at the same time.
I'd rather use something that works with block device directly, rather than something that depends on the filesystem code and may lead to filesystem corruption and potential for kernel instability. Also it seems like a weird design decision to fill flash with files, when in Linux there's trivial access to block device directly.
It's also possible to write 64bit address of each 8 byte block to every such block, and avoid pseudorandom generator, and potentially have more insight to what happened when the block ends up mapped to unexpected location.
1) All microSD cards have a high failure rate.
2) Cheap cards sourced directly from China are usually fake and will fail a format test. I tried multiple times and could never find a reliable source.
3) MS Bitlocker is a security measure that also seems to serve as a reliability test. Cards with physical memory reliability issues seem more prone to write failures with Bitlocker. It's better to know about this up front.
4) If your data is really important, always make a backup copy of any card.
5) Physically, microSD cards are fairly durable and even water resistant thanks to being encased in epoxy.
I have one on my watch strap and take it wherever I go, even the shower and pool. Just make sure it is dry before plugging it in.
https://www.thingiverse.com/thing:6784665