DBCC CHECKALLOC allows to verify whether disk space allocations are proper or not for a database.
Syntax:
DBCC CHECKALLOC
[
( database_name | database_id | 0
| , { REPAIR_ALLOW_DATA_LOSS | REPAIR_FAST | REPAIR_REBUILD } ]
)
We can give either DB name or its ID.If 0 is given,than it will check alloactions for current database.Take a backup of database,before issuing Repair.