- When RAC is used, O_DIRECT is the default option to open files in NFS. However, there are some cases where O_DIRECT is not used and the database may lose a write. For this case the NFS mount point options are in accordance with Note 359515.1
- There is another case that is specific to HP when NFS is used without the forcedirectio IO option where the database may end up losing IO.
- Lost IO may cause different errors like:
ORA-600  in a media recovery
ORA-1499 on "analyze table validate structure cascade"
ORA-8102 on delete/update
- Some of these errors are signs of logical corruptions on undo segments, redo log files and inconsistencies between tables and indexes.
- There are some cases where O_DIRECT is not used in RAC environment due to unpublished bug 5856342. Without this fix in a RAC environment using NFS the database may lose a write unless DIRECTIO is explicitly specified.
@ See Bug 7006179
- There is another case that is HP specific where Oracle does not check for forcedirectio in the mount options due to Bug 6922729. See Note 6922729.8
- For Bug 5856342 in order to prevent this issue install an Oracle RDBMS version greater than 10.2.0.3 or specify DIRECTIO in the database parameter file like:
filesystemio_options=DIRECTIO or SETALL
- For Bug 6922729 (HP specific) install an one off patch for it or specify forcedirectio in the mount options for Oracle Files. See Note 6922729.8