Pardon my ignorance but I am pretty clueless when it comes to databases.

For some reason , MT4.1 would not generate my backup.zip (presumably the db is too large / it times out) ; whatever the case , I decided to go in for a MySQL dump instead. Thats successfully done and the resulting file is a 100 Mbs.

I have kept it aside as a local back up in case of emergencies , but when it does occur - is this the same as using MT to generate a backup.zip ? Did I get all the entries , templates and every other thing thats inside the MT installation ?

Say I want to do a fresh install of MT4.21 and use this file to recreate the blog - Possible ? Easy / Fast or slower than the backup.zip method? Any place that has a guide for restoring in such a scenario? Please advise.

MT4's Backup function will include all templates, entries, pages, comments, settings, etc, as well as all assets. I bet the "all assets" part is what makes the backup choke for you; that's what does it for me. Your MySQL dump includes everything but the assets.

The way I do it is to make regular MySQL dumps, and periodically back up the other files (including Assets).

By all assets do you mean the images that I upload for the entries as well ?

By "all assets" I mean anything that shows up in the Manage Assets screen. If it's not there it's not included by the Backup function.

If the Assets are images, I think you will store them in an external media before uploading onto DB