Dropping and recreating a Clustered Index can definitely be used to move data to another disk. This is one of several documented/recommended ways to move data of certain tables to another disk in case the original disk got too small or too slow. So the statement itself is correct, but sort of incomplete.

Incomplete, because it requires additional actions : the creation of a new Filegroup on a different disk and the "ON <new-filegroup>" clause in the CREATE INDEX statement.

Excerpt from the SQL 2005 Books Online :

Because the leaf level of a clustered index and the data pages are the same by definition, creating a clustered index and using the ON partition_scheme_name or ON filegroup_name clause effectively moves a table from the filegroup on which the table was created to the new partition scheme or filegroup. Before creating tables or indexes on specific filegroups, verify which filegroups are available and that they have enough empty space for the index. For more information, see Determining Index Disk Space Requirements.

However - I sense some sort of inconsistency here.

I repeatedly read that "data is *copied* to the leaf pages of the Clustered Index". That would contradict the phrase that it "effectively moves a table", because the original Table would still exist with its original data pages.

So - is the data from the original Table physically *copied* or *moved* to the Clustered Index leaf pages ?

If they are copied - what happens to the original Table ? Does it still occupy the diskspace and add to the database size but is not used anymore ?

I *think* to remember that I had done this procedure once, 3-4 years ago on a SQL 2000 server, to move the Index workload to another disk.

And as far as I remember I was able to shrink the original MDF file significantly which would confirm that the data are actually moved.

So the table definition still remains in its original filegroup, but the "leaf level" with the data content is actually saved in the Clustered Index on the other filegroup/disk ?

And are table data modifications done directly on these moved data pages on the other filegroup/disk within the Clustered Index ?

Or on the original filegroup/disk and only moved physically to the Index filegroup/disk when dropping/recreating the Index ?

Very confusing.....