Raspberry Pi write cycles

dwight dkelvey at hotmail.com
Wed Aug 14 22:04:16 CDT 2019

Some of the newer larger SD cards use a different write voltage than 3.3V. There is a ways of asking the card what voltage it likes during the init.
Using the full 3.3V on these parts can damage them.
They are all required to init with 3.3V but the voltage for writing may be different.
I've only played with the ones smaller than 2GB. But any time I get a new one, I check the voltage.

From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Alexander Schreiber via cctalk <cctalk at classiccmp.org>
Sent: Wednesday, August 14, 2019 2:36 PM
To: Adam Thornton <athornton at gmail.com>; General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
Subject: Re: Raspberry Pi write cycles

On Fri, Aug 09, 2019 at 02:43:38PM -0700, Adam Thornton via cctalk wrote:
> I did have a case where the Pi I was using as secondary DNS/DHCP and as the
> secondary backup server (using USB spinning disk) destroyed its SD card.
> But then it turned out not to be the load at all.  No matter what I ran on
> that Pi, it would corrupt its SD cards in a matter of weeks (the symptom
> was that the fourth bit of some bytes would just stick on).  I assume it
> was just something broken in the Pi itself.

The two usual suspects:
 - standard consumer sd cards don't do so well outside of their design
   use case (mostly cameras and media players) and I suspect a journaling FS
   (which is a perfectly reasonable default, usually ext4 these days,
    for Linux) is probably especially bad - so I recommend looking for
   industrial grade SD cards, they cost a little more, are usually only
   available in smaller sizes (I've seen 8, 16, 32 GB) but they tend to
   last a lot longer
 - sub-par power supply, having the power brown out a little is _bad_
   for basically any kind of reliable operation - make sure your PSU
   can actually reliably deliver enough juice (ISTR the recommendation being
   3+ amps), I suppose the "official" ones from the Pi foundation should
   be up to the job

> (Traffic encryption via simh is incredibly painful.  You have to turn login
> delay waaaaay up to run NetBSD on VAX on a Pi if you want to be able to ssh
> into it; the machine itself runs fine-ish, but the zillions of cycles to
> encrypt the traffic swamps it in no time.)

If you want to stick with the Raspberry Pi platform, what kind of Pi are
you currently using? If it is a Pi 3, maybe try a Pi 4, that is noticeably
beefier. Note: with the Pi 4, you have to use the official power supply
and cable as they screwed up the USB-C side (by _not_ exactly copying the
schematic in the specs, saving one resistor on the BOM with the result that
high end cables will mis-recognize the Pi as an 'audio accessory' and not
power it).

> And, you know, if you manage to cause my SD cards in those machines to
> fail, well, gosh, guess I'm out $10 or so for a new one.  I'm not bothering
> to back up any of the stuff inside 'em,

I assume you've got a master image that you just write to a new SD card,
replace card, power cycle Pi, done?

Kind regards,
"Opportunity is missed by most people because it is dressed in overalls and
 looks like work."                                      -- Thomas A. Edison

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