Thursday, December 31, 2009

ntpdate no server suitable for synchronization found

I was configuring one of head node of our cluster server to synchronise from our time server in our organisation, and in turn the head node becomes a NTP Server for the compute nodes that on a private IP addresses. As I was configuring the compute nodes and encounter "ntpdate[4933]: no server suitable for synchronization found"

I configured the ntp servers and ntp clients according to Setting up NTP Server for Local Network. And yet the error remain unresolved. Finally, I came across a solution

  1. Open /etc/ntp/step-tickers and replace with the name of your local NTP Server
  2. Open /etc/ntp/ntpservers and replace with the name of your local NTP Server
  3. Restart your ntp services. You should eradicate the problem

Sunday, December 27, 2009

Configuring NFS Server for Performance

Finally, a more detailed writeup on NFS configuration which I was hoping to blog. Finally it is done.
Do read Configuring NFS Server for Performance

Friday, December 25, 2009

Configure TCP for faster connections and transfers

On a default Linux Box, the TCP settings may not be optimise for “bigger” available network bandwidth connections and transfer available for 100MB+. Currently, most TCP settings are optimise for 10MB settings. For more information, on how to configure, read my Linux Cluster Blog Configure TCP for faster connections and transfers

Thursday, December 24, 2009

NFS Client Recommended Configuration

NFS is one of the most commonly used file networked file system. Quite often we build it ourselves using standard out-of-the-box hardware we find. This NFS Client Recommended Configuration (my blog too) shows in slightly more details how to configure the mounting of the NFS clients

Tuesday, December 22, 2009

Sunday, December 20, 2009

booh - photo album generator

Booh is a free software static Web-Album generator for Linux. It takes series of photos and videos, and automatically build static web pages to browse them.

Booh has a number of unqiue features compared to the other dynamic web-album genertor. The fulling listings is at the Booh website. Here a subset of the list
  1. automatic rotation of portrait photos thanks to information read in .jpg file (EXIF)
  2. immediate display of images (preloading in browser)
  3. sub-albums support
  4. multi-processor support to speed up thumbnails generation
  5. Full video support, including thumbnailing (with seek time specification possibility) and transcoding
  6. ..... and much more. See Booh Website

Saturday, December 19, 2009

Using yum to download the rpm package that have already been installed

Firstly, download the yum-utils method
yum -y install yum-utils

To download a package that have been installed, please use yumdownloader instead
yumdownloader ganglia-gmond

Error: Missing Dependency: is needed by package ganglia-gmetad (epel)

This is the continuation of Blog Entry Error: Missing Dependency: rrdtool = 1.2.27-3.el5 is needed by package rrdtool-perl
  1. When I'm installing Ganglia on my CentOS, I've did the following:
    # yum install rrdtool ganglia ganglia-gmetad ganglia-gmond ganglia-web httpd php
    However, instead I got the followings "Error: Missing Dependency: rrdtool = 1.2.27-3.el5 is needed by package rrdtool-perl"
  2. To resolve it, similar to the earlier Blog Entry, I install rrdtool first. But when I use the command
    # yum install ganglia ganglia-gmetad ganglia-gmond ganglia-web httpd php
    There is still error "Error: Missing Dependency: is needed by package ganglia-gmetad (epel)...."
  3. To resolve the issue, you have to manually get rid of the latest rrdtool (x86-64) installed by EPEL and install the rrdtool-1.2.27-3.el5.x86_64
    # yum remove rrdtool-1.3.8-2.el5.rf.x86_64

    # yum install rrdtool-1.2.27-3.el5.x86_64
  4. Install the Ganglia and its related tools
    # yum install ganglia ganglia-gmetad ganglia-gmond ganglia-web httpd php

Friday, December 18, 2009

Using CentOS GUI Package Manager

If you wish to X forward the CentOS GUI Package Manager to your Windows Terminal ot Linux Box, you may wish to do the following first....

Step 1: Establish the Remote Connection
  1. Using Putty, Xming to forward X11 (For Windows Terminal)
  2. Speeding and Compressing X forwarding Traffic (For Linux Box)
Step 2: Install pirut
  1. Using yum effectively (Part 2)

Implementation of HPC as a Service - the Shanghai Supercomputer Center

The Shanghai Supercomputer Center (SSC) was founded in December 2000. It is the first high performance computing platform open to the whole public in China and currently is the country’s leading supercomputer centre.......

Read more on HPC as a Service from Scientific Computing World

Installing Cairo-Dock for Fedora 11

Cairo-Dock is an animated application launch bar for the desktop, comparable to the dock in Mac OS X. Cairo-Dock. You can use Cairo-Dock with OpenGL and is compatible with Compiz-Fusion, Beryl, Compiz and Xcompmgr,

Currently Cairo-Dock packages are available on rpmfusion-free repositories.. To install cairo-dock, simply
# yum install cairo-dock\*

For further information
  1. Cairo-Dock website (non-English)
  2. Cairo-Dock Wiki (English)
  3. Screenshots of Cairo-Dock

Thursday, December 17, 2009

Sun HPC ClusterTools 8.2.1

Sun HPC ClusterTools 8.2.1 software is an integrated toolkit that allows developers to create and tune Message-passing Interface (MPI) applications that run on high performance clusters and SMPs. Sun HPC ClusterTools 8.2.1 is based on OpenMPI v1.3.4

Wednesday, December 16, 2009

OpenMPI 1.4 is ready for download

OpenMPI v1.4 is ready for download. According to the OpenMPI v1.4 README file, the different between v1.4 and the previous version 1.3.4 is the fix for Libtool 2.2.6b's issues.

Tuesday, December 15, 2009

Showing uptime

uptime is a good old favourite where system admin uses it to show how long the system has been up and running.

$ uptime
01:17:33 up 1 day, 18:16,  4 users,  load average: 0.00, 0.02, 0.00

Monday, December 14, 2009

2 Storage Trends from SuperComputing 2009

This is an interesting articles about the rise of smaller storage vendors who is making wave with their storage innovation. An interesting read Two Storage Trends From SuperComputing 2009

Sunday, December 13, 2009

Fixing your system with FirstAidKit

Since Fedora 10, FirstAidKit package has been included in the Fedora Distribution. Basically, Firstaidkit is an automated recovery tool that brings together common recovery processes and applies them to a system. It is built on top of a pluggable architecture.

  1. To install FirstAidKit
    # yum install firstaidkit
  2. To run the automated process of the recovery tool, run
    # firstaidkit -a
  3. To view a list of available plug-ins
    # firstaidkit --list
For more information on FirstAidKit, see First Aid Kit by Fedora

Saturday, December 12, 2009

Tips on useradd and usermod commands

Today it is back to the basis again.

useradd and usermod are very often used utilities. They are several useful paramenters which we can use for the creation and maintenance of user accounts.

  • -c (Comments and Descriptions of the account. Using quotation is necessary if you are using multiple words
  • -d (home directory of the account. If -m is used, copy the home directory as well)
  • -e (Assign a expiration date for the account in MM/DD/YYYY format)
  • -f (Set the number of days after a password expires until the account is permanently disabled. The default option is -l which disable this option)
  • -g (primary group that the account belongs to)
  • -G (list of groups that user belongs to)
  • -l (Change login name of the account to the name supplied after -l option)
  • -u (Change the userid for the account) 

Friday, December 11, 2009

Forcing NIC to operate at Full Duplex using Ethtool

This is a follow up blog entry from Using ethtool to check and change Ethernet Card Settings

To force the NIC to use full duplex, 100Mbps, and autonegotiate off, you can
put this in /etc/sysconfig/network-scripts/ifcfg-eth0
ETHTOOL_OPTS="speed 100 duplex full autoneg off"

This is taken from ethtool from softpanorama.

Thursday, December 10, 2009

Using ethtool to check and change Ethernet Card Settings

ethtool is used for querying settings of an ethernet device and changing them. ethtool is the replacement tool for mii-tool

# ethtool eth0
 As seen in the above diagram, ethtool information is very informative and helpful for diagnostic

Other useful  command includes
# ethtool -i eth0 (provide information regarding eth0 including drivers)
# ethtool -S eth0 (provide information regarding the speed and other information)

Taken from ethtool from softpanorama. You can use ethtool command to set specific parameter on the NIC
# ethtool -s eth0 speed 100 duplex full autoneg off

Wednesday, December 9, 2009

Mounting CD or DVD with the command line

Back to the Basics.....

To mount a CD-ROM or DVD on LINUX, you can use the following command,

# mount -t iso9660 -o ro /dev/dvd /media/dvd
(assuming /media/dvd is the mount point)

Saturday, December 5, 2009

Compiz and Emerald to make Linux Desktop cool

Emerald is a custom window decorator that is shipped with Compiz. It is one of the most and easily configurable window manager.

Emerald is usually available as an additional package and has to install seperately.
# aptitude install emerald

Once installed you can launch the Emerald Theme Manager and choose your preferred theme or customise your look and replace. Once configured
$ emerald --replace

To import interesting theme, you can go to to download the latest theme. To load the theme, simply use the Emerald Theme Manager to import in the .emerald file


Friday, December 4, 2009

Speeding and Compressing X forwarding Traffic

To run the an X application over SSH connection, you can use the
$ ssh -X

Do note that for the remote Server shich you are connecting to must have X forwarding enabled. To configure, go to /etc/ssh/ssh_config/
X11Forwarding yes

If the SSH is setup with trusted X11 Forwarding ie in the /etc/ssh/ssh_config file,
ForwardX11Trusted yes

You can compress and speed up the X forwarded connection
$ ssh -Y -C
  • -Y to enable trusted X11 forwarding. Trusted X11 forwardings are not subjected to the X11 SECURITY extension controls. So it will boost speed.
  • -C to compress the data