Debian DRBD: How to resize drbd volume on top of LVM

Submitted by root on Sat, 11/29/2014 - 17:36

The examples below are done on an environment where drbd volume resides on lvm logical volume and the filesystem is reiserfs.

a. If you want to shrink it, you will have to reduce first the filesystem on the primary node then the logical volume on both nodes. Afterwards you execute the resize command for drbd on primary node.
Be careful, in order to shrink the filesystem, you will have to umount it and obviously to stop the services before that (nfs, apache, etc.).

Primary node:

umount /nfs

AIX: ssh fail to start on wpar

Submitted by root on Wed, 11/26/2014 - 14:23

In this situation, ssh was unable to start because the wpar was restored from standalone machine backup (mksysb).
However, even if this is not your case, you can try to see if the procedure will fix your ssh.

SSH doesn't want to start:

gzaix@root:/home/root # lssrc -s sshd         
Subsystem         Group            PID          Status 
 sshd             ssh                           inoperative
gzaix@root:/home/root # startsrc -s sshd
0513-059 The sshd Subsystem has been started. Subsystem PID is 18415656.

Debian: How to Set Up A Highly Available (cluster) NFS Server with DRBD and Heartbeat

Submitted by root on Wed, 11/26/2014 - 00:32

This tutorial describes how to configure a two nodes cluster to support NFS server with filesystem on DRBD volume. Without further writing, read on if you are curious ;)

Prepare the disk and create the needed vg/lv on both nodes:

cfdisk /dev/sdb
pvcreate /dev/sdb1
vgcreate nfsvg /dev/sdb1
lvcreate -n nfs -L25G nfsvg
lvcreate -n drbd -L150M nfsvg

Macports: Current platform "darwin 14" does not match expected platform "darwin 13"

Submitted by root on Thu, 11/20/2014 - 23:48

You have upgraded to Yosemite and found this error while trying to upgrade macports via command line?

fmbp:~ root# port -v selfupdate
Error: Current platform "darwin 14" does not match expected platform "darwin 13"
Error: If you upgraded your OS, please follow the migration instructions: https://trac.macports.org/wiki/Migration
OS platform mismatch
    while executing
"mportinit ui_options global_options global_variations"
Error: /opt/local/bin/port: Failed to initialize MacPorts, OS platform mismatch

How to install python 2.7 on Red Hat Enterprise Linux Workstation release 6.5 (Santiago)

Submitted by root on Wed, 11/19/2014 - 11:34

Red Hat Enterprise Linux Workstation release 6.5 (Santiago) comes with python 2.6 and if you want to install 2.7 you will discover you do not have it on repository.

All you have to do is:

1. Add python 2.7 repository:

sudo sh -c 'wget -qO- http://people.redhat.com/bkabrda/scl_python27.repo >> /etc/yum.repos.d/scl.repo'

2. Install python 2.7:

[root@florian src]# yum install python27

The following packages will be installed:

How to add an ISCSI disk on linux server

Submitted by root on Tue, 10/21/2014 - 12:03

So you have configured a brand new iscsi disk and want to put it to use in linux client?
No problem, read below!

Note: in our example, the ISCSI server is on 192.168.69.66

1. Discover the disks:

venus:~# iscsiadm -m discovery -t sendtargets -p 192.168.69.66
192.168.69.66:3260,3 iqn.2014-07.ro.gz.sun:swap-venus

2. activate them:

How to be sure network interfaces have always the same names

Submitted by root on Mon, 10/20/2014 - 16:25

You are here because sometimes you find the network interfaces renamed after any tiny modification (like kernel upgrade for example). Well, fortunately there are ways to prevent this by binding the mac address to specific names. There are several ways to achieve this. Read on.

Check Activation Lock Status on iOS Devices via Apple iCloud Website

Submitted by root on Thu, 10/02/2014 - 13:25

If you want to buy a new iPhone second hand, make sure you check it before paying up as you can do nothing with it if it's locked to another apple id.

Up until now there was no page to check if the device is locked or not. Apple has released the "Activation Lock Status" tool which is accesible via iCloud.com which alows users to enter a Device IMEI or Serial Number to check it's activation lock status.

ShellShock - Fix Bash on Debian Lenny

Submitted by root on Wed, 10/01/2014 - 15:48

How to fix bash on Debian Lenny and older debian versions.

ShellShock - Fix Bash on Debian Squeeze

Submitted by root on Wed, 10/01/2014 - 12:20

How to fix bash on Debian Squeeze

CVE-2014-6278 CVE-2014-6277 - bash: code execution via specially crafted environment variables

Submitted by root on Wed, 10/01/2014 - 09:49

There is a new bash vulnerability for which there are no technical details so I presume it is scarier than the one mentioned few days ago. Fortunately there is already a patch.

Shellshock - Bash Code Injection Vulnerabilty (CVE-2014-6271)

Submitted by root on Thu, 09/25/2014 - 13:52

Security researchers from Red Hat have uncovered a new exploit in the common "Bash" command shell found in OS X, Linux, AIX and many other *nix platforms which can be used to deploy malicious code with minimal effort. Due to the ubiquity of the Bash shell, the exploit can also affect a wide variety of different web-connected devices and properties, including unsecured websites, smart home appliances, servers, and more.

As mentioned above, this vulnerability is not limited to only one platform but in the same time in doesn't affect the average consumer because even if they have "bash" in their computers, they do not use it in a way that it can be vulnerable. Unless you are using your computer as a server that accepts commands from untrusted sources (like web servers for example) (and then only if it sets environment variables based on commands from untrusted sources) you do not have to worry about.

How to remve an ISCSI disk from linux server without reboot

Submitted by root on Tue, 07/15/2014 - 22:45

I am sure this is well known by the ones working daily with this technology but it's still important to have it around. Of course, those who are not aware have better use for what is written in this article.

Networking ABC - questions and answers

Submitted by root on Mon, 07/07/2014 - 22:42

Define Network?

A network is a set of devices connected by physical or virtual media links.
A network is a connection of two or more nodes via a physical or virtual link but also two or more networks connected by one or more nodes.

What is a Link?

Link is the virtual or physical medium used to connect two or more computers.

What is a node?

Taking as example the response from the question above, the computers are called Nodes.

OpenSSL Heartbleed Bug

Submitted by root on Thu, 04/10/2014 - 11:45

What is Heartbleed Bug?
What is the CVE-2014-0160?
How widespread is this?

Many questions, explanations and technical details are mentioned here: http://heartbleed.com/

The goal of this article is not to repeat what is there but rather to make a summary and point out the most important (and some extra stuff too):

How to repair a sparsebundle image

Submitted by root on Fri, 11/01/2013 - 21:55

In this tutorial I will show you how to repair a sparsebundle image. It's not difficult but it can take some time, depending of the size of your image.
Also, please do note that some images are so damaged that they cannot be repaired so do not throw stones at me if you cannot fix yours.

OS X Misc Stuff

Submitted by root on Wed, 02/01/2012 - 20:52

How to start finder from command line:

Open up Terminal and run the command below (dot means current directory).
user@osx$ open .

How to restart the graphical interface of OS X:

user@osx$ sudo killall -HUP WindowServer

How to retrieve CPU information via command line in OS X:

sysctl -n machdep.cpu.brand_string
system_profiler | grep Processor

Linux World

Submitted by root on Fri, 12/09/2011 - 16:24

Solaris World

Submitted by root on Fri, 12/09/2011 - 16:12

Apple World

Submitted by root on Tue, 11/29/2011 - 21:28

Articles, tutorials related to Apple devices and operating systems.

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