FUA behaviour on 6i controller

[Simon Adams_2]

When SQL Server writes data to a file it uses the Forced Unit Access flag to ensure that the data is written to 'stable media'. Some controllers take this to be the actual disk, others regard it as being written to a battery backed write cache.

In either case the controller tells the OS that 'yes, its on stable media', but on a 6i controller with 50% Read / 50% Write cache, what is considered to be the stable media? The cache or the disk?


Thanks

Simon