Pi hacks

pihacks

# http://raspberrypi.stackexchange.com/questions/169/how-can-i-extend-the-life-of-my-sd-card
# http://www.a-netz.de/2013/02/ramdisks-for-the-raspberry/
# http://web.archive.org/web/20140701023126/http://raspberry.pi.gw.gd/t50-Using-ZRAM.html

#zram
sudo modprobe zram zram_num_devices=1
lsmod | grep zram

Script Contents: 
#!/bin/sh -e
### BEGIN INIT INFO
# Provides:          mkzswap
# Required-Start:    checkfs
# Required-Stop:
# Default-Start:     S
# Default-Stop:
# Short-Description: Compressed Ram Swap
# Description:       swappapapap
### END INIT INFO

case "$1" in
  start)
	echo $(($(sed 's/MemTotal: *\([0-9]*\).*/\1/;q' /proc/meminfo) * 1024)) >/sys/block/zram0/disksize
	mkswap /dev/zram0
	;;
  *)
	echo "Usage: $0 start" >&2
	exit 3
	;;
esac

:


/proc settings





Code:

vm.min_free_kbytes = 2048
vm.swappiness=100
vm.laptop_mode=3600
vm.overcommit_memory=1
vm.page-cluster=0
vm.vfs_cache_pressure=1
you need to add the swap on the fstab and add zram to /etc/modules

kernel modules :





Code:

# grep zram /etc/modules
zram num_devices=4

num_devices could be 1 as well .. i just like to have some spare for tests

fstab : 





Code:

# grep zram /etc/fstab
/dev/zram0      none            swap    sw,pri=10       0       0



# Swap off
sudo dphys-swapfile swapoff

TEMP Files

1. edit /etc/default/tmpfs and set:
RAMLOCK=yes
RAMSHM=yes
RAMTMP=yes


I'd recommend the following sizes:

TMPFS_SIZE=10%VM
RUN_SIZE=10M
LOCK_SIZE=5M
SHM_SIZE=10M
TMP_SIZE=25M


2. enable additional directories using /etc/fstab

tmpfs   /var/log                tmpfs   size=20M,defaults,noatime,mode=0755 0 0 
tmpfs   /var/cache/apt/archives tmpfs   size=100M,defaults,noexec,nosuid,nodev,mode=0755 0 0
tmpfs   /var/spool/cups         tmpfs   size=100M,defaults,noatime,mode=0755 0 0
tmpfs   /var/spool/cups/tmp     tmpfs   defaults,noatime,mode=0755 0 0


3. use the script /etc/init.d/prepare-dirs to create missing directories in /var/log so that all daemons start

4. Make the script executable:
sudo chmod 755 /etc/init.d/prepare-dirs

5. Make sure that the script will be started first on boot before your daemons start: 
sudo update-rc.d prepare-dirs defaults 01 99

contents of /etc/init.d/prepare-dir:
#!/bin/bash
#
### BEGIN INIT INFO
# Provides: prepare-dirs
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Required-Start:
# Required-Stop:
# Short-Description: Create needed directories on /var/log/ for tmpfs at startup
# Description: Create needed directories on /var/log/ for tmpfs at startup
### END INIT INFO

# needed Dirs
DIR[0]=/var/log/apt
DIR[1]=/var/log/fsck
DIR[2]=/var/log/lighttpd
PRM[2]="www-data.www-data"
DIR[3]=/var/log/cups
DIR[4]=/var/log/news
DIR[5]=/var/log/ntpstats
DIR[6]=/var/log/samba
DIR[7]=/var/log/lastlog
DIR[8]=/var/log/exim
DIR[9]=/var/log/watchdog
DIR[10]=/var/log/ConsoleKit

case "${1:-}" in
  start)
    typeset -i i=0 max=$(echo "${!DIR[*]}" | tr " " "\n" | sort -nr | head -n1)
    while (( i <= max ));do
      if [ -n "${DIR[$i]}" ];then
        mkdir -p ${DIR[$i]}
        chmod 755 ${DIR[$i]}
      fi
      i=i+1
    done
    # set rights
    typeset -i i=0 max=$(echo "${!PRM[*]}" | tr " " "\n" | sort -nr | head -n1)
    while (( i <= max ));do
      if [ -n "${PRM[$i]}" ];then
        chown -R ${PRM[$i]} ${DIR[$i]}
      fi
      i=i+1
    done
    ;;
  stop)
    ;;
  restart)
    ;;
  reload|force-reload)
    ;;
  status)
    ;;
  *)
    echo "Usage: $SELF start"
    exit 1
    ;;
esac