This is not a simple task, and depending on the size of your tables may require a chunk of downtime.
First, you have to define the new file group:
ALTER DATABASE MyDatabase
add filegroup NewGroup
Then, create an appropriate file for that file group, for example:
ALTER DATABASE MyDatabase
add file
(
name = NewFile
,filename = 'C:\temp\NewFile.ndf'
,size = 100MB
,maxsize = unlimited
,filegrowth = 100MB
)
to filegroup NewGroup
To move a table onto the file group, you have to create a clustered index for that table on the file group. If you've got a clustered constraint (such as a unique or primary key), you'll have to drop it first. Here's one way to move such a table:
-- Set up sample table
CREATE TABLE MyTable
(
Data varchar(100) not null
constraint PK_MyTable
primary key clustered
)
-- Can't "move" primary key constraint to a new file group
ALTER TABLE MyTable
drop constraint PK_MyTable
-- This will move the data in the table to the new file group
CREATE clustered index Move_MyTable
on MyTable (Data)
on NewGroup
-- Still in the new file group, just no index
DROP INDEX MyTable.Move_MyTable
-- Recreate the primary key, keeping it on the new file group
ALTER TABLE MyTable
add constraint PK_MyTable
primary key clustered (Data)
on NewGroup
It is just a bit fussy, so be sure to test everything on copies of your databases first!