Service Pack 4 for SQL Server 2000, due out any day now, has a number of new features oriented toward making the product easier to support.  One of these is the new detection and reporting of stalled or stuck I/O operations.  A stalled I/O is an I/O operation that SQL Server has submitted to the operating system and is taking an inordinant amount time to complete.  A stuck I/O is an I/O operation that has been submitted by the server to the OS and never completes.  Usually, these types of problems are due to either driver problems or hardware problems -- that is, they're completely outside of SQL Server.  They're notoriously difficult to debug and troubleshoot.  To the typical SQL Server end user, they manifest themselves as poor performance or what seems like a hang.  SP4 features detection and reporting of these conditions via messages written to the error log.  My next column in MSDN Magazine (also due out any day now) will give you the details and lay out some example scenarios where the new functionality makes all the difference.