I'm using a FILESTREAM enabled database that is hosted on SQL Server 2008 Standard Ed on a Windows 2003 server and am seeing some long waits of types PREEMPTIVE_OS_%. Specifically, PREEMPTIVE_OS_GETFILESIZE when executing GET_FILESTREAM_TRANSACTION_CONTEXT(). I'm wondering if anyone can shed some light on what the PREEMPTIVE_OS_% wait types for FILESTREAM operations are.
Interesting. Do you have any anti-virus software that might be attempting real-time scans on the files and delaying SQL Server from opening them quickly? That's the first thing that springs to mind.