yes I know that there is no performance gain configuring 2 log files for 1 database, but my idea is not performance related. Let's say I've a storage with some fast disks (SAS or SSD) and other slow disks (NL-SAS) the space on fast disks is very expensive so I've to cut my LUN with thriftness.
My idea is to have the first log file on fast disks, the first log file should has enough space to do all the work that the database needs. The second log file on the slow disks its scope is to act as a "life valve" if the primary file consumes all its space, the database start to use the second file.
So I've maximum performance if the database does not exceed the size on fast disks and, in case of overflowing that space, my databases does not go offline.
I'm wrong somewhere?