Disabling NetworkManager on Fedora/Centos

systemctl disable NetworkManager.service
sudo chkconfig --level 2345 NetworkManager off
chkconfig network on

Edit /etc/sysconfig/network-scripts/ifcfg-ethXXX where XXX is each interface you want to be active on boot. Make sure the following are set:

NM_CONTROLLED=no
ONBOOT=yes

Some Isilon notes

Isilon, Isilon, how do you work… no one really knows. However here are a few useful, seemly undocumented commands you can run when ssh’d into a node:

Finding large files

fstat is a bit like lsof in the Linux world, but exists on FreeBSD:

fstat | sort -k 8 -n -r | more

Finding serial number

isi config
quit

gathering and uploading info, usually required for a support call

isi_info_gather

Show status/alert info

isi status
isi alerts

Do something on all cluster nodes

isi_for_array 'df -h'

C++ Multiply without multiply

A couple of ways for write multiply, without using multiply…

int multiply(int value,int mul) {

int ret=0;

int mulabs = mul;
if(mulabs < 0) mulabs = 0 – mulabs;

for(int n=0;n<mulabs;n++) {
ret += value;
}

if(mul < 0) ret = 0-ret;

return ret;
}

int multiply2(int value,int mul) {

int total=0;

for(int n=30;n>=0;n–) {

if((mul & (1 << n)) > 0) {
total += value << n;
}
}
return total;

}

Bluray Laser CNC – version 0.2

Building on the messy hack. That was the previous version of my Bluray laser cutter, I decided to make a slightly more solid second version.

Still using the ULN2003 as a driver, and the same BluRay laser diode as before. And as always of course, laser safety goggles were used at all times when the laser was in operation.