Oracle, for example, recommends use of RAID 1 for the redo log files. For the database files, Oracle recommends either RAID 5, provided the write overhead is acceptable, otherwise Oracle recommends either RAID 1 or RAID 0+1. A fuller discussion of RAID is outwith the scope of this book and the interested reader is referred to the papers by Chen and Patterson (1990) and Chen et al. (1994).