Re: What is your strategy to save non volatile data?

From	Don Y <blockedofcourse@foo.invalid>
Newsgroups	comp.arch.embedded
Subject	Re: What is your strategy to save non volatile data?
Date	2016-08-11 15:36 -0700
Organization	A noiseless patient Spider
Message-ID	<noiukh$ble$1@dont-email.me> (permalink)
References	<nohs7p$ff3$1@dont-email.me> <noi142$ih$1@dont-email.me> <noi3gv$8qc$1@dont-email.me> <noipdo$nnv$1@dont-email.me>

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On 8/11/2016 2:07 PM, David Brown wrote:
>> I've used a circular buffer into which "tagged" parameters are placed.
>> On restart, I "play back" the buffer to restore the latest versions of
>> the parameters encountered, there.  This lets me mix snapshots and
>> incremental updates in the same mechanism.
>
> I've done something like that too (that's sort of what I meant be a log
> structure - though I didn't describe it in detail).  It worked well for a flash
> based system - once one sector is getting a bit full, I ran a garbage
> collection pass by running through the buffer copying the latest parameters
> into a new sector, and then erased the old buffer with the outdated values.

It has the advantage that it also serves as a debugging tool.

I employ such "black boxes" (named for the fabled flight recorders on
aircraft) in most subsystems as cheap (fast, low resource) mechanisms
for keeping track of what is happening in a subsystem.  In a /post mortem/,
I can peruse their contents to see what was happening in each module just
prior to the "end".

For "settings" that need to be preserved as part of the normal operation
of a device (i.e., more like "state" than "configuration data"), there
can be frequent writes to these BB's -- every interaction with the user!
As such, they can reveal a lot of what else was happening in the system.

(If you just have a "configuration mode", then the amount of traffic is
probably too infrequent to be of much use in a /post mortem/ -- unless,
of course, you've a bug in your UI!)

Thread

What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-11 14:48 +0200
  Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 06:27 -0700
  Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-11 16:12 +0200
    Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 07:53 -0700
      Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 08:27 -0700
        Re: What is your strategy to save non volatile data? bitrex <bitrex@de.lete.earthlink.net> - 2016-08-11 12:11 -0400
          Re: What is your strategy to save non volatile data? bitrex <bitrex@de.lete.earthlink.net> - 2016-08-11 12:12 -0400
            Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 11:35 -0700
              Re: What is your strategy to save non volatile data? bitrex <bitrex@de.lete.earthlink.net> - 2016-08-11 20:59 -0400
          Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 11:33 -0700
        Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-12 00:21 +0200
          Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 15:40 -0700
      Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-11 23:07 +0200
        Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-12 00:17 +0200
          Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 15:30 -0700
            Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-12 09:02 +0200
              Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-12 09:29 -0700
            Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-12 11:54 +0200
              Re: What is your strategy to save non volatile data? John Devereux <john@devereux.me.uk> - 2016-08-12 13:14 +0100
                Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-12 15:22 +0200
              Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-12 09:40 -0700
                Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-12 22:40 +0200
                Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-13 09:44 -0700
                Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-14 23:01 +0200
          Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-12 09:52 +0200
            Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-12 16:30 +0200
              Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-12 17:09 +0200
        Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 15:36 -0700
        Re: What is your strategy to save non volatile data? Paul <paul@pcserviceselectronics.co.uk> - 2016-08-12 03:21 +0100
    Re: What is your strategy to save non volatile data? bitrex <bitrex@de.lete.earthlink.net> - 2016-08-11 12:19 -0400
      Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-11 23:49 +0200
        Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 15:37 -0700
    Re: What is your strategy to save non volatile data? John Devereux <john@devereux.me.uk> - 2016-08-11 20:50 +0100
    Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-12 00:16 +0200
      Re: What is your strategy to save non volatile data? Paul <paul@pcserviceselectronics.co.uk> - 2016-08-12 03:34 +0100
      Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-12 11:59 +0200
  Re: What is your strategy to save non volatile data? Paul Rubin <no.email@nospam.invalid> - 2016-08-11 11:29 -0700
  Re: What is your strategy to save non volatile data? Les Cargill <lcargill99@comcast.com> - 2016-08-12 12:15 -0500
  Re: What is your strategy to save non volatile data? Joe Chisolm <jchisolm6@earthlink.net> - 2016-08-12 12:10 -0500
    Re: What is your strategy to save non volatile data? Paul <paul@pcserviceselectronics.co.uk> - 2016-08-12 22:00 +0100
  Re: What is your strategy to save non volatile data? Tim Wescott <tim@seemywebsite.com> - 2016-08-13 12:06 -0500
    Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-13 23:42 +0200
      Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-13 15:55 -0700
      Re: What is your strategy to save non volatile data? Paul <paul@pcserviceselectronics.co.uk> - 2016-08-14 00:08 +0100
      Re: What is your strategy to save non volatile data? Tim Wescott <tim@seemywebsite.com> - 2016-08-13 19:06 -0500
        Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-22 09:46 +0200

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