Rsync: Performance NFS Boost

If you use two Linux Servers with NFS Shares connect over Gigabit Interfaces for Backups, you perhaps remark performance problems on using rsync.
It does often pause transmissions or reach only a rate of 32Mb/s. That’s bad and waste time and energy.

Background:
After some Tests of running Backups with single files and compressed big archives, the scans of my tools like iftop, systat, iptraf found out that the used Option „rsync -avz“ was the bottle neck, cause the Data Rate break down at intervals. The „z“ compress option was described on howtos as must have for slower networks did not work like a „on the fly permanent transmission“. My two Test Servers use each 3 Gigabit bonded NIC Cards, if the rsync command compress the Files, they were first pulled to RAM Cache and compressed there later after a small pause send.

Solution:
If you disable and remove the „z“ option and on used bash scripts as „batch run“ removing the „v“ Option too, i was able to send Data at range of 133MB/s.

On fast Network do:

$rsync -a /source/ /nfs-mounted-destination

Openwrt: Turn older Router into Wifi Accesspoint Repeater Extender Solar Powered

At the Summer Time you need perhaps a Wifi Extender for your Garden??

Solution:

  • TP Link 841/N (low power/Battery 9V/Solar /Type-N-allows external planar Antennas!!), 3600+4300 (USB-NAS/CIFS/SFTP/Classroom Library with USB Strorage)
  • Openwrt 15.XX Calmer as OS with Firewall, Webinterface and REALTIME Monitor for Traffic and Connections!
  • Easy Setup, replace the OS by the TP-Link-Updater, reboot and Login to Openwrt
  • You got professional Options!
  • works as Firewall, Extender, Repeater, WIFI-to-WIFI Bridge, LAN-to-WIFI Bridge, NTP-Server, DNS/DHCP Server
  • can isolate connected WIFI Clients
  • can handle different WIFI SSIDs / Networks on same Hardware
  • modded Hardware can be used with 5Volts of Power! (841 removed Resistor)
  • runs Freifunk OS for Public Free WIFI Guestnet (without Password Login and VPN to Public Internet Gateways for anonymous Web Access)
  • free security updates, backup and restore of settings!
  • free support by published Wikis, many Manuals on Internet and of course by me
  • free Download od the Sofware at openwrt.org

freifunk

Raspberry Pi: Howto build a Local Network Monitor for Intrusion Logging Watchdog

Today the count of network devices at home networks grows up weekly, cause more and more home devices like freezers, coffee engines, dishwasher and more got builtin wifi interfaces. To have a Control Unit you can use a raspberry pi2 as cheap Network Monitor Logger.

The Raspian by default offers builtin free tools, like arp, arp-scan, nmap, ping to easy monitor a network. If you have learned some commands and the bash scripting you can fast create a Network Logger, perhaps with analyse tools to mail alerts if new „MAC“ NIC Adresses are seen. Every network device uses a owned MAC-ID like „00:d0:23:09:df:XX“. Thats like a car chassis number.

 

arp-scan
arp-scan

How to Setup:

  1. Install Raspian (Debian) on a SDCARD for PI2
  2. Boot the PI2 to Raspian
  3. Upgrade the OS
  4. Install lighttpd as Webserver for Outputs and start him
  5. Install the  Networktools „arp, arp-scan, nmap, ping“
  6. Edit root crontab to run the commands every minute like „* * * * *  /usr/sbin/arp-scan -l -I eth0 > /var/www/arp1/2-scan.log“
  7. Open a webbrowser to http://pi2/arp-scan.log #You should see the Text like inside the Image
  8. write a bash script with the „diff“ or „md5sums“ command to check the arp1-scan.log against the arp2-scan.log if any changes you can output a mail thru exim4 mailserver..

Advantage? A Pi2 is a powerful LAN WATCHDOG with 1Watt/hour and Mail Output Support to your devices! for free..