Beginners • Re: SD Cards have the same declared capacity, but different actual capacity

Manufacturers can increase flash yields if they accept devices with more defective pages (equating to capacity loss).

I have more of the same Kingston Canvas Select SD Cards. I plugged in other Kingston Canvas Select, using card reader, and gparted shows exactly the same information, so I don't think it is some defects.

All cards have blocks that are not "good", have gone bad, and the card will not use those. More blocks will go bad over time from normal wear and tear and the card will simple stop using those. Eventually, if enough of them go bad the card will go into read only mode and at that time you can copy stuff off it and onto a new card.

Card can refuse to use blocks for writing, but how can it shrink the total capacity of the card without destroying the partitions on it? And I already wrote, that the same other card has the same parameters. By the way that Kingston SD Cards are almost new. SanDisk is much older.

All SD cards i got so far reach at least the advertised capacity. Maybe the bottom one is a fake.

I bought them in trusted local computer store. If they sell fake goods, then I don't know where to buy original goods .

The same thing happens with HDDs and SSDs.

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Once, I compared some Seagate Barracuda (already with bad smart and errors) and WD Gold and they both had exact the same capacity.

I just wonder what is the smallest actual capacity of the 32, 64, 128 Gb SD Card can be? Will the Kingston 128Gb lose 4Gb compared to SanDisk 128Gb? But I don't have so much SD Cards to compare.

Statistics: Posted by POPEYE — Wed May 22, 2024 9:37 pm

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