Returns a row for each pending I/O request in SQL Server. VIEW SERVER STATE permission is needed for the requesting user.
This query tells you the amount of outstanding I/O:
select vfs.database_id, df.name, df.physical_name,vfs.file_id, ior.io_pending, ior.io_handle, vfs.file_handle
from sys.dm_io_pending_io_requests ior
inner join sys.dm_io_virtual_file_stats (DB_ID(), NULL) vfs on (vfs.file_handle = ior.io_handle)
inner join sys.database_files df on (df.file_id = vfs.file_id)
where df.name = ‘Log file name'