Performance tuning is part of a DBA's job; at the same time, the DBA also has to take care of the SQL Server instance, the amount of disk space consumed by database(s), providing high availability to the database users, managing database backup/restore policy as a part of disaster management, and a lot more.
Out of these listed responsibilities, disk management is also one of the important tasks to manage. The DBA needs to keep a watch on it and claim any free space consumed by unused indexes, manage the size of log files and data files, and arrange for a larger-sized disk, if needed.
In Chapter 9, and in this chapter, we have discussed many times that an index comes with some overhead, and one of the overheads is that the index consumes disk space. So, this is the time to see how much space an index consumes, as either low space or no space on disk raises performance issues, and sometimes the query stops working due to the unavailability of disk...