Re^2: Debugging CPAN problem

"SD cards have a limited life - about 1K writes before things start to fail"

Holy crap! 1k writes only? What kind of cards are you buying? I have several Pis (eight, 10 if I include my zeroWs), a couple of them that have been running for several years (literally) doing all manner of intense disk activity constantly, and I've only ever had two cards fail on me over that span across all of my Pis, and one was a direct result of accidentally applying 48v DC to the power pin while I had it connected to an SD reader while I was writing software for a micro controller.

I use mainly Kingston cards.

Comment on Re^2: Debugging CPAN problem

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Re^3: Debugging CPAN problem by davies (Monsignor) on Dec 22, 2020 at 23:13 UTC
My father always used to ask, "Is that something you know or something you've been told?". This is what I have been told. SD cards have logic that spreads the writes around so that no one point gets lots of hits. If you do a complete overwrite - which is what my code does - 1K times, you are reaching the end of the useful life of the device. When I put this to a salesman of SSDs, he did not deny the basic arguments but said that the power consumption more than made up for the shorter life (than spinning rust) and that in most cases, data were written far fewer times than read and that the read speed was a further advantage and and and. But he didn't deny the effective write limit, although I have no hard evidence for the 1K figure I had been told. I'll bet that, over time, the number of writes will increase. The cards I have that have failed most are Verbatim, but I have other reasons for avoiding anything of that brand in future. Regards, John Davies	[reply]
Re^4: Debugging CPAN problem by haukex (Archbishop) on Dec 24, 2020 at 10:16 UTC
I have no hard evidence for the 1K figure I had been told. What I learned when studying this years ago is that flash cells have an endurance of more like around 10k writes, though I'm sure with the advancement of the technology that's increased* (I've head figures of up to 1M writes). Conversely, the wide spread of flash technology also means that there will probably be companies producing cheap, lower-quality flash, with less write cycles. * I went on DigiKey and picked a few current NAND Flash ICs at random, from different manufacturers (PDFs: 1, 2, 3) and each of them specifies an endurance of 100K Program/Erase cycles and data retention of 10 years.	[reply]