DBA_HIST_INSTANCE_RECOVERY

DBA_HIST_INSTANCE_RECOVERY displays the historical monitoring of the mechanisms available to the user to limit recovery I/O. This view contains snapshots of V$INSTANCE_RECOVERY.

Column	Datatype	NULL	Description
SNAP_ID	NUMBER	NOT NULL	Unique snapshot ID
DBID	NUMBER	NOT NULL	Database ID for the snapshot
INSTANCE_NUMBER	NUMBER	NOT NULL	Instance number for the snapshot
RECOVERY_ESTIMATED_IOS	NUMBER		Number of dirty buffers in the buffer cache. In the Standard Edition, this column is always null.
ACTUAL_REDO_BLKS	NUMBER		Current actual number of redo blocks required for recovery
TARGET_REDO_BLKS	NUMBER		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 LOG_CHECKPOINT_TIMEOUT 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 LOG_CHECKPOINT_INTERVAL has been set.
FAST_START_IO_TARGET_REDO_BLKS	NUMBER		This column is obsolete and maintained for backward compatibility. 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), then 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, then the value of this field is the current estimated MTTR.
ESTIMATED_MTTR	NUMBER		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). This value tells you how long you can expect recovery to take based on the work the system is doing right now.
CKPT_BLOCK_WRITES	NUMBER		Number of blocks written by checkpoint writes
OPTIMAL_LOGFILE_SIZE	NUMBER		Redo log file size (in megabytes) that is considered optimal based on the current setting of FAST_START_MTTR_TARGET. It is recommended that all online redo logs be configured to be at least this value.
ESTD_CLUSTER_AVAILABLE_TIME	NUMBER		Estimated time (in seconds) that the cluster would become partially available should the instance fail. This column is only meaningful in a Real Application Clusters (RAC) environment. In a non-RAC environment, the value of this column is null.
WRITES_MTTR	NUMBER		Number of writes driven by the FAST_START_MTTR_TARGET parameter
WRITES_LOGFILE_SIZE	NUMBER		Number of writes driven by the smallest redo log file size
WRITES_LOG_CHECKPOINT_SETTINGS	NUMBER		Number of writes driven by the LOG_CHECKPOINT_INTERVAL parameter or the LOG_CHECKPOINT_TIMEOUT parameter
WRITES_OTHER_SETTINGS	NUMBER		Number of writes driven by other reasons (such as the deprecated FAST_START_IO_TARGET parameter)
WRITES_AUTOTUNE	NUMBER		Number of writes due to auto-tune checkpointing
WRITES_FULL_THREAD_CKPT	NUMBER		Number of writes due to full thread checkpoints