Switching forum from url.com/forum to forum.url.com

[kursed]

Can anyone guide here, as to how can this be performed, without losing my pages indexed with Google? And without causing any loss of data?

[Snakehill]

Without losing data, sure. But Google will have to re-index your pages (and related links).

You will need to move all data from the url.com/forum folder to forum.url.com. Since the database is on the same server, linked to the same url, it shouldn't be any problem.

Be sure that in your vBulletin options (site name/url) you change the link too.