Placing Text Pages on a Separate Device

When you create a table with text or image columns, the data is stored on a separate chain of text pages.

A table with text or image columns has an additional entry in sysindexes for the text chain, with the name column set to the name of the table preceded by the letter “t” and an indid of 255.

Use sp_placeobject to store the text chain on a separate device, giving both the table name and the name of the text chain from sysindexes:
sp_placeobject textseg, "mytab.tmytab"
Note: By default, a chain of text pages is placed on the same segment as its table. After you execute sp_placeobject, pages that were previously written on the old device remain allocated, but all new allocations take place on the new segment.

If you want the text pages to be on a particular segment, first create the table on that segment (allocating the initial extent on that segment), then create a clustered index on the table to move the rest of the data to the segment.