Hi,

Actually, disabling a nonclustered index deletes the physical index; only the definition is retained. Per BOL:

"The index definition of a disabled index remains in the system catalog with no underlying index data."

As for specific usages, we had a case where there were unused indexes on a production environment taking up 10% of the database (~450GB). There is still legacy code external to the database which contains index hints. While we checked the code, we couldn't guarantee there were any references missed. Disabling the indexes allowed us to force an error that the index was disabled as opposed to an index not existing. With this method in the case of this error we wouldn't have to worry about finding the correct script to recreate the index - we could just rebuild it without knowing the definition.

Chris