How can I get fluent nhibernate to create a varbinary field in a sql server 2005 table that uses a field size of varbinary(max)? At the moment I always get a default of varb
I'm not sure why your ActiveRecord example is not working, but there you might try setting the length of the column.
With Fluent NHibernate, you should be able to do
Map(x => x.FileData) .WithLengthOf(2147483647)