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AWS fault-tolerant web app with GlusterFS

Building fault-tolerant and scalable web application is a MUST for every serious business and platform. Here you can find nice overview of techniques to achieve that in AWS.

But since AWS is a platform which allows you to build whatever-you-want on the top of it, some extra work is needed to achieve completely redundant and [...]

NFS AWS howto

So… everyone are speaking about having single storage unit in AWS. That’s a real demand these days, and here is one way of doing that. The answer is – NFS!

So basically, you do the following:

- launch/create VPC

http://docs.aws.amazon.com/AmazonVPC/latest/GettingStartedGuide/ExercisePreqs.html

- create VPC private subnet

http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Scenario2.html

- Launch instance in public subnet, and create NFS [...]

mdadm raid configuration

Few steps you need to perform, for example creating Raid1 and preserving it’s creation after server reboot:

# yum install mdadm

Now, first check your devices, for this example we will presume their names are /dev/xvdf and /dev/xvdg (modify this to suit your needs):

# mdadm –create –verbose /dev/md0 –level=1 –raid-devices=2 /dev/xvdf /dev/xvdg

Next, we [...]

Sony Vaio Ubuntu touchpad issue – RESOLVED

I have installed Ubuntu 11 to my Sony Vaio laptop, but mouse touchpad was working very bad (i.e. was not working).

Solution:

First, check your Sony version, just to be sure:

# dmidecode -s system-product-name

After that, tell Ubuntu to use your touchpad as mouse PS2:

# echo options psmouse proto=imps | tee -a /etc/modprobe.d/psmouse.conf; [...]

Couldn’t untar /root/.cpan/ – RESOLVED

Recently I wanted to install some Perl modules for mail server vacation.pl script, but it was failing do to so:

# perl -MCPAN -e shell # cpan> install DBD::mysql … Uncompressed /root/.cpan/sources/authors/id/C/CA/CAPTTOFU/DBD-mysql-4.022.tar.gz successfully Using Tar:/bin/tar xvf /root/.cpan/sources/authors/id/C/CA/CAPTTOFU/DBD-mysql-4.022.tar: Couldn’t untar /root/.cpan/sources/authors/id/C/CA/CAPTTOFU/DBD-mysql-4.022.tar

Hmm, but /bin/tar exists:

[...]

rsync/scp issue – is your shell clean?

Recently I just wanted to copy some files from one server to another, regularly using scp. However, even if I opened all ports, transfer failed with SCP, but without any error message, just the output from my .bashrc which I used as identification for every server (I just put simple “echo server1″ into .bashrc as [...]

TCPflow

Instead of using “tcpdump”, why not trying “tcpflow”?

From the man page:

tcpflow is a program that captures data transmitted as part of TCP connections (flows), and stores the data in a way that is convenient for protocol analysis or debugging. A program like tcpdump(4) shows a summary of packets seen on the wire, but [...]

Bash script for changing file extension

Bash script for changing extension type on many files inside the directory (for example, if you have many pictures ending in .jpeg and you want to change them to .gif):

#!/bin/bash

echo "source extension?" read source

echo "destination extension?" read target

for i in `ls *$source`; do

file=`ls $i | sed "s/$source/$target/"`

echo "changing source [...]

Amazon VPC + ipsec + racoon + quagga

If you need Amazon VPC but you don’t have any piece of hardware equipment that will satisfy requirements (as described here), don’t panic! There is a solution – you can use Linux to route your traffic to Amazon VPC!

This scenario has been successfully tested and is working on following configuration:

Debian 6 with one [...]

NERDTree vim plugin

Very useful thing if you want to extend your usage of VIM (which is, by my opinion, best editor in the world )

Basically it is acting as plugin to vim, after you run vim just type “:NERDTree” and see the magic – it will open tree with all files and directories from location where [...]