After-imaging is an optional recovery mechanism that lets you recover data and transactions if a disk fails. AI files must be kept on separate disks from the database and BI files, so after-imaging I/O activity does not contribute to I/O activity on the disks where BI and database files are stored. However, after-imaging creates a significant amount of I/O that can affect performance. You can reduce the I/O impact of after-imaging by:

  • Using an after-image writer (AIW) on systems with an Enterprise database license
  • Raising the AI block size

The sections that follow describe these options.