Category: System Administration

If you’re like me you probably have an environment that is running on some virtual platform and like everyone else you have built a template to spin Linux systems. One of the things lately we were running into was the “70-persistent-net.rules”, which associated MAC address to Network interfaces.

The easiest way I have found to disable this was to do the following, it’s not pretty but works.

rm /etc/udev/rules.d/70-persistent-net.rules

echo “#” > /lib/udev/rules.d/75-persistent-net-generator.rules

Happy hacking.

I have been using Spacewalk for a while now and really like a lot of the built-in functionality. I have been using it to build out and manage a lot of my Red Hat, and CentOS installations.

The latest thing I have been using it for it to manage is my Hadoop cluster build out and configuration updates. I think that it helps to be able to control as much of it as possible from one management system. I know there are applications like Ambari out there, but to be honest who wants to add another tool if they don’t have to go to my site.

Here’s the link to my work blog about it.

http://gotomojo.com/managing-your-linux-deployments-with-spacewalk/

Here is the problem.

[root@bob ~]# service virt-who start

Démarrage de virt-who : Traceback (most recent call last):

File “/usr/share/virt-who/virt-who.py”, line 33, in <module>

from subscriptionmanager import SubscriptionManager, SubscriptionManagerError

File “/usr/share/virt-who/subscriptionmanager.py”, line 24, in <module>

import rhsm.connection as rhsm_connection

ImportError: No module named rhsm.connection

[FAILED]

There is a simple work around. Install the Scientific Linux 6 python-rhsm package.

Name : python-rhsm

Version : 1.1.8 Vendor : Scientific Linux

Release : 1.el6 Date : 2013-02-22 01:54:26

Group : Development/Libraries Source RPM : python-rhsm-1.1.8-1.el6.src.rpm

Size : 0.27 MB

Packager : Scientific Linux

Summary : A Python library to communicate with a Red Hat Unified Entitlement Platform

Description :

A small library for communicating with the REST interface of a Red Hat Unified

Entitlement Platform. This interface is used for the management of system

entitlements, certificates, and access to content.

First install python-simplejson

[root@bob ~]# yum install python-simplejson

Then pick a mirror from http://rpm.pbone.net/index.php3/stat/4/idpl/20813982/dir/scientific_linux_6/com/python-rhsm-1.1.8-1.el6.x86_64.rpm.html and download python-rhsm-1.1.8-1.el6.x86_64.rpm and install it

[root@bob ~]# rpm –install python-rhsm-1.1.8-1.el6.x86_64.rpm

Then start virt-who

[root@bob ~]# service virt-who start

If you have been around computer systems long enough everyone knows how import disk performance is, espeacially with database systems. There’s the standard htparm -tT and dd test the everyone does, but it really does give you the whole picture. What you really want is to test read, write, re-read, re-write, read backwards, read strided, fread, fwrite, random read, pread ,mmap, aio_read, and aio_write. For that I would recommend using Iozone. It gives you a better idea of what’s going on.

http://www.iozone.org

The other day I and a few of my colleges were talking about a easy way to deploy and undeploy war files from the command line like you could through the Tomcat Web Application Manager portal and being on a python kick, I started writing it in python. After an hour or two I realized that I had made this way more complex then I need to.  I had been reading theApache Tomcat 6.0 Manager App HOW-TO and I was using curl to test all the commands from localhost.

shell> curl –anyauth -u admin:password http://localhost:8080/manager/start?path=/myapp

So now after slapping myself in forehead and saying “duh!”. I decided I could write this as shell script and have it knock out in 20 minutes.

So here what I came up with tomcat-cli.sh.

–Cheers