From:
http://extremeshok.com/blog/debian/raspberry-pi-raspbian-server-preparation/
http://extremeshok.com/blog/debian/raspberry-pi-raspbian-tuning-optimising-optimizing-for-reduced-memory-usage/
========================================================================
Raspi-config -> memory_split -> 224 224MiB for ARM, 32MiB for VideoCore
Raspi-config -> boot_behaviour -> Should we boot straight to desktop? -> NO
Raspi-config -> ssh -> Would you like the SSH server enabled or disabled? -> Enable
apt-get install vim vim-nox screen unzip zip python-software-properties curl ntp ntpdate -y
root@raspberrypi:~# free -htl
total used free shared buffers cached
Mem: 215M 46M 168M 0B 8.4M 21M
Low: 215M 46M 168M
High: 0B 0B 0B
-/+ buffers/cache: 16M 199M
Swap: 99M 0B 99M
Total: 315M 46M 268M
Replacing OpenSSH with Dropbear | Save: +10MB RAM
This will reduce the memory consumption by 10MB, however you will be sacrificing:
ssh portforwarding and ssh logging.
Install dropbear
openssh-client is installed to provide SCP support for the dropbear server
apt-get install dropbear openssh-client
Stop OpenSSH server
you will not loose your current SSH connection, if you are connected via ssh
/etc/init.d/ssh stop
Enable dropbear to start at boot-time
sed -i 's/NO_START=1/NO_START=0/g' /etc/default/dropbear
optional: prevent root logins
sed -i 's/DROPBEAR_EXTRA_ARGS=/DROPBEAR_EXTRA_ARGS="-w"/g' /etc/default/dropbear
optional: prevent password logins
sed -i 's/DROPBEAR_EXTRA_ARGS=/DROPBEAR_EXTRA_ARGS="-s"/g' /etc/default/dropbear
optional: prevent password logins for root
sed -i 's/DROPBEAR_EXTRA_ARGS=/DROPBEAR_EXTRA_ARGS="-g"/g' /etc/default/dropbear
optional: prevent root logins and prevent password logins
sed -i 's/DROPBEAR_EXTRA_ARGS=/DROPBEAR_EXTRA_ARGS="-w -s"/g' /etc/default/dropbear
optional: change the listening port from 22 to 2222
sed -i 's/DROPBEAR_PORT=22/DROPBEAR_PORT=2222/g' /etc/default/dropbear
Start Dropbear
/etc/init.d/dropbear start
Test, make sure you can connect to the server over ssh (using an ssh client).
Remove OpenSSH
Remove the extra tty / getty’s | Save: +3.5 MB RAM
tty2-tty6 will be disabled. We are keeping tty1 for console, unless you choose to disable it.
sed -i '/[2-6]:23:respawn:\/sbin\/getty 38400 tty[2-6]/s%^%#%g' /etc/inittab
optional: disable getty on the Raspberry Pi serial line
sed -i '/T0:23:respawn:\/sbin\/getty -L ttyAMA0 115200 vt100/s%^%#%g' /etc/inittab
Replace Bash shell with Dash shell | Save: +1 MB RAM
Replacing Bash with Dash will increase the system’s overall performance ie. speed up the system
boot, reduce disk space, use fewer libraries (save memory) and is more reliable:
Dash is an acronym for Debian Almquist shell (dash). It is a Unix and Linux shell which is much
smaller than bash but still aiming at POSIX-compliancy. dash is a POSIX-compliant implementation
of /bin/sh that aims to be as small as possible. dash is a direct descendant of the NetBSD version
of ash (the Almquist SHell), ported to Linux in early 1997. It was renamed to dash in 2002.
dpkg-reconfigure dash
Use dash as the default system shell (/bin/sh)? Yes
Enable a 512MB swapfile
Customize the size of the swap file, 512MB recommended.
echo "CONF_SWAPSIZE=512" > /etc/dphys-swapfile
Initialize the swapfile
dphys-swapfile setup
Start/enable the swapfile
dphys-swapfile swapon
Enable better usage of the swap
Default swappiness is 1, we will change this value to 10, which will allow for better memory
usage at the expense of more swap usage.
sed -i 's/sortstrategy = 3/sortstrategy = 0/g' /etc/preload.conf
suggested correction:
sed -i 's/vm.swappiness=1/vm.swappiness=10/g' /etc/sysctl.conf
Reboot
shutdown -r now
Optional: Enable Preload to speed up load times
Note: this will increase memory usage, recommended for desktop to increase overall responsiveness.
Do NOT enable for servers.
Install
apt-get install preload
Configure for flash
sed -i 's/vm.swappiness=1/vm.swappiness=10/g' /etc/sysctl.conf
suggested correction:
sed -i 's/sortstrategy = 3/sortstrategy = 0/g' /etc/preload.conf
Optimize / mount
sed -i 's/defaults,noatime/defaults,noatime,nodiratime/g' /etc/fstab
suggested correction:
is unnecessary, nodiratime is not checked if noatime is specified.
Disable IPv6
Most users will not need ipv6 support and if you are only using a local there is no need.
Disable it to save the resources and speed up networking.
echo "net.ipv6.conf.all.disable_ipv6=1" > /etc/sysctl.d/disableipv6.conf
Disable the kernel module
echo 'blacklist ipv6' >> /etc/modprobe.d/blacklist
Remove IPv6 hosts
sed -i '/::/s%^%#%g' /etc/hosts
Reboot
shutdown -r now
Replace Deadline Scheduler with NOOP Scheduler
NOOP scheduler is best used with solid state devices such as flash memory.
sed -i 's/deadline/noop/g' /boot/cmdline.txt
Reboot
shutdown -r now
Replace rsyslogd with inetutils-syslogd and remove useless logs
Reduce memory and cpu usage. We just need a simple vanilla syslogd.
Also there is no need to log so many files. Just dump them into /var/log/(cron/mail/messages)
remove rsystlog
apt-get -y remove --purge rsyslog
install syslogd
apt-get -y install inetutils-syslogd
Create a vanilla syslogd setup
Stop syslogd
service inetutils-syslogd stop
Remove old logs
for file in /var/log/*.log /var/log/mail.* /var/log/debug /var/log/syslog; do [ -f "$file" ] && rm -f "$file"; done
for dir in fsck news; do [ -d "/var/log/$dir" ] && rm -rf "/var/log/$dir"; done
Create syslog.conf
echo -e "*.*;mail.none;cron.none\t -/var/log/messages\ncron.*\t -/var/log/cron\nmail.*\t -/var/log/mail" > /etc/syslog.conf
Configure logrotate
mkdir -p /etc/logrotate.d
echo -e "/var/log/cron\n/var/log/mail\n/var/log/messages {\n\trotate 4\n\tweekly\n\tmissingok\n\tnotifempty\n\tcompress\n\tsharedscripts\n\tpostrotate\n\t/etc/init.d/inetutils-syslogd reload >/dev/null\n\tendscript\n}" > /etc/logrotate.d/inetutils-syslogd
Start syslogd
service inetutils-syslogd start
Set a static IP and remove DHCP-Client
Reduces CPU and memory.
Create a backup config
cp -f /etc/network/interfaces /etc/network/interfaces.dhcp-backup
Edit file: /etc/network/interfaces
replace
iface eth0 inet dhcp
with
iface eth0 inet static
#set your static IP below
address 192.168.1.107
#set your default gateway IP here
gateway 192.168.1.1
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
Reboot
shutdown -r now
