V$INSTANCE_RECOVERY

This view monitors the mechanisms available to users to limit recovery I/O. Those mechanisms are:

• Set the initialization parameter LOG_CHECKPOINT_TIMEOUT
• Set the initialization parameter LOG_CHECKPOINT_INTERVAL
• Set the initialization parameter FAST_START_MTTR_TARGET
• Set the size of the smallest redo log

  See Also: Oracle9i Database Performance Tuning Guide and Reference for more information on limiting recovery I/O, and how MTTR recovery times are determined by Oracle LOG_CHECKPOINT_INTERVAL FAST_START_MTTR_TARGET

  Column	Datatype	Description
  RECOVERY_ESTIMATED_IOS	NUMBER	Contains the number of dirty buffers in the buffer cache. In the Standard Edition, this column is always NULL.
  ACTUAL_REDO_BLKS	NUMBER	The current actual number of redo blocks required for recovery
  TARGET_REDO_BLKS	NUMBER	The current target number of redo blocks that must be processed for recovery. This value is the minimum value of the following 3 columns, and identifies which of the 3 user-defined limits determines checkpointing.
  LOG_FILE_SIZE_REDO_BLKS	NUMBER	Maximum number of redo blocks required to guarantee that a log switch does not occur before the checkpoint completes.
  LOG_CHKPT_TIMEOUT_REDO_BLKS	NUMBER	Number of redo blocks that need to be processed during recovery to satisfy the LOG_CHECKPOINT_TIMEOUT parameter. The value displayed is not meaningful unless that parameter has been set.
  LOG_CHKPT_INTERVAL_REDO_BLKS	NUMBER	Number of redo blocks that need to be processed during recovery to satisfy the LOG_CHECKPOINT_INTERVAL parameter. The value displayed is not meaningful unless that parameter has been set.
  FAST_START_IO_TARGET_REDO_BLKS	NUMBER	This column is obsolete and maintained only for compatibility reasons. The value of this column is always NULL.
  TARGET_MTTR	NUMBER	Effective MTTR (mean time to recover) target value in seconds. The TARGET_MTTR value is calculated based on the value of the FAST_START_MTTR_TARGET parameter (the TARGET_MTTR value is used internally), and is usually an approximation of the parameter's value. However, if the FAST_START_MTTR_TARGET parameter value is very small (for example, one second), or very large (for example, 3600 seconds), the calculation will produce a target value dictated by system limitations. In such cases, the TARGET_MTTR value will be the shortest calculated time, or the longest calculated time that recovery is expected to take. If FAST_START_MTTR_TARGET is not specified, the value of this field is the current estimated MTTR.
  ESTIMATED_MTTR	NUMBER	The current estimated mean time to recover (MTTR) based on the number of dirty buffers and log blocks (0 if FAST_START_MTTR_TARGET is not specified). Basically, this value tells you how long you could expect recovery to take based on the work your system is doing right now.
  CKPT_BLOCK_WRITES	NUMBER	Number of blocks written by checkpoint writes