doc(location):Describe how to disable swap file

[EVA-2020-02.git] / doc / location / README.org

diff --git a/doc/location/README.org b/doc/location/README.org
index 7158a730f0955c7fd8b9dd7e30da9156d47f784f..ebabe81e84a8f32f52335c99ed2d50b396c7055d 100644 (file)
--- a/doc/location/README.org
+++ b/doc/location/README.org
@@ -1,10 +1,9 @@
 * Location Logging
 This document was created by Steven Baltakatei Sandoval on
-<2020-06-29 Mon 12:14> under a [[https://creativecommons.org/licenses/by-sa/4.0/][Creative Commons BY-SA 4.0 license]]. It
-was updated by Steven Baltakatei Sandoval on <2020-06-29 Mon 22:06>.
+~2020-06-29T12:14Z~ under a [[https://creativecommons.org/licenses/by-sa/4.0/][Creative Commons BY-SA 4.0 license]]. It
+was updated by Steven Baltakatei Sandoval on ~2020-06-30T17:13Z~
 #+TITLE: Ninfacyzga-01 Manual
 #+AUTHOR: Steven Baltakatei Sandoval
-#+DATE: 2020-06-29T22:16Z
 #+EMAIL: baltakatei@gmail.com
 ** Narrative
 Ninfacyzga-01 records (logs) its position in time and space using a
@@ -112,7 +111,6 @@ conflict so a simple stacking and soldering with long header pins is
 possible.
 
 **** Software Setup
-
 ***** Install Executables
 
 Install Raspbian 10 Buster onto an SD card image. See the Raspberry Pi
@@ -132,6 +130,34 @@ Install ~syncthing~ for log file transfer capability.
 Place ~age~ binary (the one compiled for ARM CPU architecture for
 Linux) in ~$HOME/.local/bin~.
 
+***** Disable Swap File
+Since standard Raspbian 10 install involves copying unencrypted file
+system image to SD card which is mounted by the Raspberry Pi, system
+memory may be written to disk in the form of a Swap file as described
+[[https://ideaheap.com/2013/07/stopping-sd-card-corruption-on-a-raspberry-pi/][here]]. In order to reduce the chance that location log data is ever
+written to disk, swap file functionality must be disabled.
+
+To view the status of the swap file in Raspbian 10, run ~free -m~:
+
+#+BEGIN_EXAMPLE
+pi@ninfacyzga-01:~$ free -m
+              total        used        free      shared  buff/cache   available
+Mem:            432          86          36          21         309         268
+Swap:            99           0          99
+#+END_EXAMPLE
+
+The swap file may be disabled by:
+
+#+BEGIN_EXAMPLE
+pi@ninfacyzga-01:~$ sudo dphys-swapfile swapoff
+pi@ninfacyzga-01:~$ sudo dphys-swapfile uninstall
+pi@ninfacyzga-01:~$ sudo update-rc.d dphys-swapfile remove
+pi@ninfacyzga-01:~$ free -m
+              total        used        free      shared  buff/cache   available
+Mem:            432          96          33          22         302         258
+Swap:             0           0           0
+#+END_EXAMPLE
+
 ***** Automatic Start Configuration
 
 Edit the user cron job list with ~$ crontab -e~ to add the following