[time-nuts] Re: Clock display on Linux systems?

[Per Molund]

piCorePlayer aka. pCP, a DIY high quality audio player for Squeezelite 
are running entirely in RAM after loading from SD card. Only 
configuration changes are written to SD card. I have been running a 
handful of these devices daily for years on cheap SD cards without any 
SD card problems.

The pCP are based on piCore Linux which is a Rasperry Pi port of the 
Tiny Core Linux. See the following links for further information on how 
to implement and use these Linux ports.

Ref. piCore Linux:
<https://iotbytes.wordpress.com/picore-tiny-core-linux-on-raspberry-pi/>
 Â Â Â  <https://github.com/mxmxmx/terminal_tedium/wiki/piCore>

and Tiny Core Linux:
 Â Â Â  <http://tinycorelinux.net/book.html>
 Â Â Â  <http://forum.tinycorelinux.net/index.php>

Regards,
 Â Â Â  Per

On 08.12.2021 23:35, Lux, Jim wrote:
> On 12/8/21 2:15 PM, Bill Dailey wrote:
>> You can also set them up so they don’t write to the SD once 
>> everything is set.  SD’s will last forever like this.  Basically read 
>> only and RAM disk.
>
>
> yes indeed - these days, with lots o'RAM on a rPi, you should boot off 
> the SD (or eMMC) and run out of RAM.  For a "clock" application, you 
> could probably structure your writes to SD (for nonvolatile storage of 
> logs, etc.) so that you limit the number of writes. If you log once an 
> hour that's just under 9000 writes/year.
>
> Typical MLC flash is good for at least 10,000 erase cycles on a page. 
> Writing data to an erased page (or the part that's not already 
> written) doesn't wear it out, but changing data in the middle of a 
> file does, because you have to erase it (consuming life), and then 
> rewrite.
>
> There are Journaling File Systems that deal with this, but I doubt 
> they're compatible with the wear leveling systems in commercial SD 
> cards. Basically, the SD card has a controller that exposes a 
> generalized interface, with the wear leveling hidden from you, and if 
> it's hidden, then the JFS doesn't really know how to manage the device.
>
> I don't know, though, it's a fertile ground - and someone may have a 
> nice JFS for a common distro for RPi and SD card.
>
>
> If you want to get real down and dirty, there are also clever schemes 
> that write all ones or zeros (depending on the device), instead of 
> erasing, and then the reader of the file knows that this means "not 
> used" - Much like the RUBOUT character on paper tape, or a similar 
> scheme used with PROMS where you don't want to erase it.
>
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