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Synchronising Devices

What is file synchronisation, why do we need it?

Imagine you are working on a project. All files and directories related to this are in a directory in one of the departmental data spaces. You are going away and will be working on your project while on the beach without internet access. You copy your project directory onto your laptop.

While on holiday you do some project work as planned. When you return to your office in CMS you continue with your project, but with the files you have in the data space. Then one day you remember you edited some files while you were away but you now cannot remember which files you edited on holiday on your laptop and which since returning on the departmental system. You will need to go through both systems picking out the newest copy of each file and watching out for any files you changed in both locations. Painful.

Ways to keep files in sync

Edit them in situ.

If you can ssh or Winex into a CMS machine then you can work on the files in your data space. On a Windows laptop you can view and edit your Maths files via WinSCP. On a Linux laptop you can use nautilus to view your files in a graphical window (see the page on copying and viewing files over the network for details).

This is the most straightforward way to manage as you have only one copy of the files, but it requires a fast reliable internet connection wherever you work.

Use an online service such as Dropbox or SpiderOak.

Run Dropbox on both computers and keep your project work in your Dropbox directory. Whenever either computer is connected to the Internet (all the time for the CMS desktops) its Dropbox folder will be synced with an online copy. To link the Maths Linux computers with your Dropbox account, simply type dropbox and follow the instructions. Once you have done this, Dropbox will start automatically whenever you launch a graphical session on a Maths Linux machine.

There are some DPA (Data Protection Act) issues with DropBox that you must be aware of.

DropBox Inc (as of 06/12/2011) has not, as far as we can tell, signed up to the International Safe Harbor Privacy Principles.

A simple summary is: do not put, without first obtaining permission, personal data about someone else into DropBox as you do not know where the data is stored.

There are many alternative online backup and file synchronisation services available. One which seems better than most is SpiderOak as there are some privacy guarantees and it installs on Ubuntu. This is not an official recommendation.

Use specialist file synchronisation software.

This is a more secure option as your files are stored only in your data space and on your laptop, not somewhere in the cloud.