So all you need to do is
Go to Central Administration > Application Management > Content Databases and set the existed content database to “Offline” mode
Add new content database in Central Administration > Application Management > Content Databases. (you can use different SQL server). Now all new sites will be created in this content database
Use the following command to export your site to the disk
“stsadm -o export -url http://
Delete your exported site collection in Central Administration > Application Management > Delete Site Collection
Create new empty site with the same path, via stsadm –o createweb/createsite;
Import you site to the same url, and site will be created in the new content database.
Use the following command for this
“stsadm -o import –url http://
Now you will have you sub-site in new content database. It’s not very user friendly approach, and is an error proned a bit.
But there is one small tool - SharePoint Administration Tookit, which helps you to to reorganise the whole site collections. This feature will install a new section inside “Applications”and you can move your site collection via Central Administration interface.
And there is a nice article on this