Problem: Unable to copy data files when 10g database is in hot backup mode

So, our customers are FINALLY making the transition to 10gR2 databases this summer and we're having all kinds of great "Oops!" moments. Here's a good example:

PROBLEM:

• A tablespace's physical files cannot be copied even when the tablespace is in hot backup mode.
  
• We created a pretty standard 10.2.0.3 database on an AIX 5L box, and when we put the tablespaces into hot backup mode, we were unable to copy the data files to a backup location as AIX kept reporting that they were locked.

Of course our first reaction was "HUH?!", and after much head scratching, sysadmin pestering, and SAR opening, we finally got the solution from Oracle.

SOLUTION:

• There is a bug with the FILESYSTEMIO_OPTIONS init parameter in 10g that prevents the "setall" value from working correctly.
• We were able to copy the data files once we made the following change: filesystemio_options=async
  
• See MetaLink Note:434385.1