If there is anything that the recent GMail outages taught us, it's that losing access to your email for a few hours should not mean that the end of the world has arrived. I think it also served as a reminder that if you rely 100% on the cloud for access to your data, then be prepared to be disconnected from it every once in a while. Fortunately, it's quite easy to take advantage of free email services from the likes of Google while also making sure that should the worst happen, you can still access your data.

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Anyone who needs to access a unix/linux/osx machine from windows via ssh will be familiar with PuTTY, the free ssh client. PuTTYGen, available to download here, is a handy utility for creating RSA/DSA public/private keys for authentication. If you have generated your RSA keys using PuTTYGen, and would like to use them with OpenSSH on Ubuntu, you just need to follow a few simple steps:

• Install putty with: sudo apt-get install putty
• Create the public key file:
  puttygen /path/to/puttykey.ppk -L > ~/.ssh/id_rsa.pub
• Create the private key file:
  puttygen /path/to/puttykey.ppk -O private-openssh -o ~/.ssh/id_rsa

You should now be able to log into an SSH server using your private key. To install your public key simply copy from ~/.ssh/id_rsa.pub on your local machine to ~/.ssh/authorized_keys on the remote server.

It's quite common in University departments for roomfuls of very capable PCs to sit idle from 5pm until 8am everyday and all weekend. Thankfully, it's possible to turn such a wasted resource into a powerful cluster of Linux machines using freely available open source software. In fact, even a group of machines in an office, or at home, can be transformed into a similar state with the minimum of effort. By booting the PCs (or nodes) over the network, no changes are made to the current setup of the machines, so reverting back to their normal state is as simple as rebooting. This guide will bring you through the process of creating a High-Performance Computing (HPC) cluster using the latest version of the Debian GNU/Linux operating system, Diskless Remote Boot in Linux (DRBL), and Sun's Open Source N1 Grid Engine 6.

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