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Oracle® Database Reference
10g Release 1 (10.1)

Part Number B10755-01
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V$BACKUP_ASYNC_IO

V$BACKUP_ASYNC_IO displays performance information about ongoing and recently completed RMAN backups and restores. For each backup, it contains one row for each input datafile, one row for the aggregate total performance of all datafiles, and one row for the output backup piece. This data is not stored persistently, and is not preserved when the instance is re-started.


See Also:

Oracle Database Performance Tuning Guide for information on how to use this table to tune backup performance

Column Datatype Description
SID NUMBER Oracle SID of the session doing the backup or restore
SERIAL NUMBER Use count for the SID doing the backup or restore
USE_COUNT NUMBER A counter that can be used to identify rows from different backup sets
RMAN_STATUS_RECID NUMBER Owning V$RMAN_STATUS record ID
RMAN_STATUS_STAMP NUMBER Owning V$RMAN_STATUS record stamp
DEVICE_TYPE VARCHAR2(17) Device type where the file is located
TYPE VARCHAR2(9) INPUT, OUTPUT, or AGGREGATE
STATUS VARCHAR2(11) NOT STARTED, IN PROGRESS, or FINISHED
FILENAME VARCHAR2(513) Name of the backup file being read or written
SET_COUNT NUMBER Set count of the backup set being read or written
SET_STAMP NUMBER Set stamp of the backup set being read or written
BUFFER_SIZE NUMBER Size of the buffers being used to read/write the file, in bytes
BUFFER_COUNT NUMBER Number of buffers being used to read/write the file
TOTAL_BYTES NUMBER Total number of bytes that will be read or written for the file, if known. If not known, this column will be null
OPEN_TIME DATE Time the file was opened. If TYPE='AGGREGATE', then this is the time that the first file in the aggregate was opened
CLOSE_TIME DATE Time the file was closed. If TYPE='AGGREGATE', then this is the time that the last file in the aggregate was closed
ELAPSED_TIME NUMBER Time, in hundredths of a second, that the file was open
MAXOPENFILES NUMBER Number of concurrently open DISK files. This value is only present in rows where TYPE='AGGREGATE'.
BYTES NUMBER Number of bytes read or written so far
EFFECTIVE_BYTES_PER_SECOND NUMBER I/O rate that was achieved with this device during this backup
IO_COUNT NUMBER Number of I/Os that were performed to this file
READY NUMBER Number of asynchronous requests for which a buffer was immediately ready for use
SHORT_WAITS NUMBER Number of times that a buffer was not immediately available, but a buffer became available after doing a nonblocking poll for I/O completion
SHORT_WAIT_TIME_TOTAL NUMBER Total time, in hundredths of a second, taken by nonblocking polls for I/O completion
SHORT_WAIT_TIME_MAX NUMBER Maximum time taken for a nonblocking poll for I/O completion, in hundredths of a second
LONG_WAITS NUMBER The number of times that a buffer was not immediately available, and only became available after a blocking wait was issued
LONG_WAIT_TIME_TOTAL NUMBER The total time, in hundredths of a second, taken by blocking waits for I/O completion
LONG_WAIT_TIME_MAX NUMBER The maximum time taken for a blocking wait for I/O completion, in hundredths of a second