Recover failed SD card

Valeri Galtsev galtsev at
Sun Feb 24 22:14:07 UTC 2019

On 2/24/19 1:17 PM, @lbutlr wrote:
> On 24 Feb 2019, at 07:34, Valeri Galtsev <galtsev at> wrote:
>> On 2/23/19 6:46 PM, @lbutlr wrote:
>>> On 23 Feb 2019, at 13:50, Bruce Ferrell <bferrell at> wrote:
>>>> Unfortunately flash memory "wears out".  There are spare storage blocks and logic to level wear by switching th the spares when main block failures are detected.
>>> Yeah, that’s good theory, but it’s not what has happened with mine. Genrally they fail in the first few weeks. Even if it takes longer, it is not like they have been written and rewritten  many times. This isn’t a wear issue, it is an "SD Cards Break easily" issue.
>> With all statements like that I would really like to hear at least the following about failed devices:
>> 1. brand and model of device that failed on you
> Various brands. The most recent were SanDisk and Samsung.

Thanks for information. SanDisk in my observation declined in quality 
some 5-6 years ago, I'm staying away from it since. Samsung is big 
surprise for me.

>> 2. the source (vendor) you got the device from
> Microcenter or Amazon.

Amazon is where you can hit any sort of actual vendor... but unless you 
device is by good manufacturer and not counterfeit, I would consider 
Amazon as good as brick and mortar stores (MicroCenter one of them).

>> 1. High grade Samsung 128GB 100MB/s (U3) MicroSD EVO Select;
> The Samsung that failed after about six months (written to once, read maybe 100 times) was a 32GB EVOplus 80MB/s 20MB/s microSD. I don’t have the SanDisk one anymore, but it was also a 32GB with similar specs. Both decided one day they were 32MB storage devices. The SanDisk at least had the decency to do it when it was being formatted.

This is big surprise for me. I guess my statistics with Samsung Micro SD 
card is not as big as yours, and I was just lucky so far.

>> 2. This one I do not consider the best, but it survived at least 6 years of use in car camera: Micro Center class 10 Micro SD (32 GB)
> I tend not to buy store brands, but I think SanDisk makes the cards for Microcenter’s house brand.

Yes, and mine were that old before I noticed SanDisk decline in quality 
(but maybe my observation about that is wrong).

>> So, instead of generalizing, I would really like to hear the detailed information about _failed_ devises
> Too many for me to have kept close track of. They generally fail faster than I expect, but some seem to last forever. When one fails I normally try a bit to recover it, then bin it and pull out another one.

Yes, thanks again for all this information. My own statistics doesn't 
seem to be as big as yours, and I must have been lucky, or maybe the way 
I choose has some effect on it: I usually am trying to get references of 
reliability people make, and usually end up buying almost most expensive 
in a group with the same specs. It is like in what I was saying about 
other computer equipment: price grabber is your enemy.


Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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