In answer to those questions caused by lack of column space

Each week I receive a number of letters from readers asking me to expand on a previous column or explain how my comments might apply to their special circumstances. Logistics demand that I keep the length of my column to something that can be published in a newspaper, but it is not always easy. Some of the subjects I write about could easily fill a book if I were to examine all the appropriate nuances.

I have selected a few letters that typify the responses and or questions I have received on recent columns because some of the questions are important to the subject and the odds are that you will find the information useful.

My recent column on an ideal backup regimen ('No need for SOS calls with a simple backup plan to secure data', September 13) ) led to several letters inquiring about other applications I have previously recommended.

Reader Eric Spain noted: 'I have been using Carbon Copy Cloner for cloning my hard drive to an external disc and Folder Synchronizer X for daily back-ups. You did not mention these in your column. Have you found anything wrong with them?'

The answer is yes. I did not mention Carbon Copy Cloner because there are numerous reports that it does not produce accurate clones. If your main drive has 40 gig of content and your 'identical' clone has only 35 gig, that is a big discrepancy.

As for Folder Synchronizer, it reportedly alters the source drive by changing permissions, something it should not do for security reasons. For what is essentially a security software utility, this is a serious faux pas.