Google Open Source Blog: This Week's Top 10's: Universities for Google Summer of Code 2008

Google Open Source Blog: This Week's Top 10's: Universities for Google Summer of Code 2008

University of Moratuwa is the 1st in Top 10 Universities for Google Summer of Code 2008

I'm very proud to see that University of Moratuwa(UOM) is the 1st among top 10 universities. This is a BIG achievement. UoM has fist places for both Most Applicants and Most Accepts list.

Nameserver

The resolv.conf file is the resolver configuration file. It is use to configure client side access to the Internet Domain Name System (DNS). This file defines which name servers to use.

The resolver is a set of routines in the C library that provide access to the Internet Domain Name System (DNS). The resolver configuration file contains information that is read by the resolver routines the first time they are invoked by a process. The file is designed to be human readable and contains a list of keywords with values that provide various types of resolver information

Note: File name is /etc/resolv.conf and not /etc/resolve.conf.

Sample resolv.conf file

nameserver 202.54.1.10
nameserver 202.54.1.11

Setting Up Clients To Use a Proxy

http_proxy
ftp_proxy
gopher_proxy
wais_proxy


export http_proxy="http://your.proxy.server:8080/"; //export http_proxy
eg: export http_proxy=http://cache.mrt.ac.lk:3128

export ftp_proxy="http://your.proxy.server:8080/"; //export ftp_proxy
eg: export ftp_proxy=http://cache.mrt.ac.lk:3128

export gopher_proxy="http://your.proxy.server:8080/"; //export gopher_proxy
eg: export gopher_proxy=http://cache.mrt.ac.lk:3128

export wais_proxy="http://your.proxy.server:8080/"; //export wais_proxy
eg: export wais_proxy=http://cache.mrt.ac.lk:3128



No proxy

Some clients support the no_proxy environment variable that specifies a set of domains for which the proxy should not be consulted; the contents is a comma-separated list of domain names, with an optional :port part:

export no_proxy="cern.ch,ncsa.uiuc.edu,some.host:8080"

Get Money

Network File Copy using SSH

Push: Push local file to remote server.
Pull: Pull remote file from remote server to local machine.

PUSH:

• tar cvf - . | gzip -c -1 | ssh user@host cat ">" remotefile.gz

  ---

• ssh target_address cat <localfile ">" remotefile
  
• ssh target_address cat <localfile - ">" remotefile
  
• cat localfile | ssh target_address cat ">" remotefile
  
• cat localfile | ssh target_address cat - ">" remotefile
  
• dd if=localfile | ssh target_address dd of=remotefile
  
• ssh target_address cat <localfile "|" dd of=remotefile
  
• ssh target_address cat - <localfile "|" dd of=remotefile
  
• ( cd SOURCEDIR && tar cf - . ) | ssh target_address "(cd DESTDIR && tar xvpf - )"
  
• ( cd SOURCEDIR && tar cvf - . ) | ssh target_address "(cd DESTDIR && cat - > remotefile.tar )"
  
• ( cd SOURCEDIR && tar czvf - . ) | ssh target_address "(cd DESTDIR && cat - > remotefile.tgz )"
  
• ( cd SOURCEDIR && tar cvf - . | gzip -1 -) | ssh target_address "(cd DESTDIR && cat - > remotefile.tgz )"
  
• ssh target_address "( nc -l -p 9210 > remotefile & )" && cat source-file | gzip -1 - | nc target_address 9210
  
• cat localfile | gzip -1 - | ssh target_address cat ">" remotefile.gz
  

---

PULL:

ssh target_address cat remotefile > localfile

ssh target_address dd if=remotefile | dd of=localfile

ssh target_address cat "<" remotefile >localfile

ssh target_address cat "<" remotefile.gz | gunzip >localfile

---

COMPARE:

###This one uses CPU cycles on the remote server to compare the files:

ssh target_address cat remotefile | diff - localfile

cat localfile | ssh target_address diff - remotefile

###This one uses CPU cycles on the local server to compare the files:

ssh target_address cat <localfile "|" diff - remotefile

Computer cluster

A computer cluster is a group of loosely coupled computers that work together closely so that in many respects they can be viewed as though they are a single computer। The components of a cluster are commonly, but not always, connected to each other through fast local area networks। Clusters are usually deployed to improve performance and/or availability over that provided by a single computer, while typically being much more cost-effective than single computers of comparable speed or availability.



High-availability (HA) clusters

High-availability clusters (also known as failover clusters) are implemented primarily for the purpose of improving the availability of services which the cluster provides. They operate by having redundant nodes, which are then used to provide service when system components fail. The most common size for an HA cluster is two nodes, which is the minimum requirement to provide redundancy. HA cluster implementations attempt to manage the redundancy inherent in a cluster to eliminate single points of failure.

There are many commercial implementations of High-Availability clusters for many operating systems। The Linux-HA project is one commonly used free software HA package for the Linux OSs.

Load-balancing clusters

Load-balancing clusters operate by having all workload come through one or more load-balancing front ends, which then distribute it to a collection of back end Platform LSF HPC, Sun Grid Engine, Moab Cluster Suite and Maui Cluster Scheduler। The Linux Virtual Server project provides one commonly used free software package for the Linux OS.



Technologies

MPI is a widely-available communications library that enables parallel programs to be written in C, Fortran, Python, OCaml, and many other programming languages.

The GNU/Linux world sports various cluster software; for application clustering, there is Beowulf, distcc, and MPICH. Linux Virtual Server, Linux-HA - director-based clusters that allow incoming requests for services to be distributed across multiple cluster nodes. MOSIX, openMosix, Kerrighed, OpenSSI are full-blown clusters integrated into the kernel that provide for automatic process migration among homogeneous nodes. OpenSSI, openMosix and Kerrighed are single-system image implementations.

Microsoft Windows Compute Cluster Server 2003 based on the Windows Server platform provides pieces for High Performance Computing like the Job Scheduler, MSMPI library and management tools. NCSA's recently installed Lincoln is a cluster of 450 Dell PowerEdge™ 1855 blade servers running Windows Compute Cluster Server 2003. This cluster debuted at #130 on the Top500 list in June 2006.

DragonFly BSD, a recent fork of FreeBSD 4.8, is being redesigned at its core to enable native clustering capabilities. It also aims to achieve single-system image capabilities.