You can use the copy database wizard to move databases from one database instance to another.
Right-click on an existing database, choose TASKS and then at very bottom, is 'Copy Database'.
I would recommend the detach / re-attach database option, I don't like the other method, it's not reliable enough.
You'll probably want to test a couple of database detach / attach operations.
Detach takes the database offline, and makes it portable so you can change the volume, before re-attaching the database in a new location.
A few points to consider - some may apply in your case:
SQL Server backups only contain pages used
From Books Online:
The backup contains only the actual data in the database and not any
unused space.
This means that if your database has a lot of free space, the backup might be small.
You can check space usage using sp_spaceused
or a view like sys.master_files
.
Database restores recreate the data files exactly as they were backed up
Say you have a database with a 10GB data file and a 5GB log file, which you've backed up. When you restore the database, it will recreate these files as they were when they were backed up; it won't change the data layout in any way.
So it seems like your original database had a 12GB file - when restoring this file is being recreated.
Compression can be applied
Depending on your version/edition you can compress backup files (Enterprise only in SQL Server 2008) - this reduces the backup file size so might be misleading.
What can you do?
Easiest answer is to increase the size of your drive or restore to a different location.
Another option would be to look at the size of the original DB and consider if it has been maintained correctly, e.g. it may have a large transaction log file that hasn't been backed up correctly. Questions about appropriate database size and actions might be best suited to dba.stackexchange.com.
Best Answer
You shouldn't need to uninstall/install: your data and log files should be on separate disk arrays/SAN Luns from the binaries.
Saying that, 64k NFTS cluster is highly recommended all over the place.
SQL Server does IO in extents which is 8x8k pages = 64k, basically.
For actual numbers on performance differences, I can only find this http://tk.azurewebsites.net/2012/08/ (Azure, but still SQL Server)