Dynamic Performance (V$) Views, 10 of 179

V$BACKUP_ASYNC_IO

This view 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:
Oracle8i Designing and Tuning for Performance for information on how to use this table to tune backup performance.

Column Datatype Description

SID

NUMBER

The Oracle SID of the session doing the backup or restore

SERIAL

NUMBER

The 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

DEVICE_TYPE

VARCHAR2(17)

The 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)

The name of the backup file being read or written

SET_COUNT

NUMBER

The set_count of the backup set being read or written

SET_STAMP

NUMBER

The set_stamp of the backup set being read or written

BUFFER_SIZE

NUMBER

The size of the buffers being used to read/write this file, in bytes

BUFFER_COUNT

NUMBER

The number of buffers being used to read/write this file

TOTAL_BYTES

NUMBER

The total number of bytes that will be read or written for this file, if known. If not known, this column will be null

OPEN_TIME

DATE

The time this file was opened. If TYPE='AGGREGATE', then this is the time that the first file in the aggregate was opened

CLOSE_TIME

DATE

The time this file was closed. If TYPE='AGGREGATE', then this is the time that the last file in the aggregate was closed

ELAPSED_TIME

NUMBER

The time, in 100ths of seconds, that the file was open

MAXOPENFILES

NUMBER

The number of concurrently open DISK files. This value is only present in rows where TYPE='AGGREGATE'

BYTES

NUMBER

The number of bytes read or written so far

EFFECTIVE_BYTES_PER_SECOND

NUMBER

The I/O rate that was achieved with this device during this backup

IO_COUNT

NUMBER

The number of I/Os that were performed to this file

READY

NUMBER

The number of asynchronous requests for which a buffer was immediately ready for use

SHORT_WAITS

NUMBER

The number of times that a buffer was not immediately available, but a buffer became available after doing a non-blocking poll for I/O completion

SHORT_WAIT_TIME_TOTAL

NUMBER

The total time, in 100ths of seconds, taken by non-blocking polls for I/O completion

SHORT_WAIT_TIME_MAX

NUMBER

The maximum time taken for a non-blocking poll for I/O completion, in 100ths of seconds

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 100ths of seconds, 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 100ths of seconds

Column	Datatype	Description
`SID`	`NUMBER`	The Oracle SID of the session doing the backup or restore
`SERIAL`	`NUMBER`	The 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
`DEVICE_TYPE`	`VARCHAR2(17)`	The 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)`	The name of the backup file being read or written
`SET_COUNT`	`NUMBER`	The set_count of the backup set being read or written
`SET_STAMP`	`NUMBER`	The set_stamp of the backup set being read or written
`BUFFER_SIZE`	`NUMBER`	The size of the buffers being used to read/write this file, in bytes
`BUFFER_COUNT`	`NUMBER`	The number of buffers being used to read/write this file
`TOTAL_BYTES`	`NUMBER`	The total number of bytes that will be read or written for this file, if known. If not known, this column will be null
`OPEN_TIME`	`DATE`	The time this file was opened. If `TYPE`='`AGGREGATE`', then this is the time that the first file in the aggregate was opened
`CLOSE_TIME`	`DATE`	The time this file was closed. If `TYPE`='`AGGREGATE`', then this is the time that the last file in the aggregate was closed
`ELAPSED_TIME`	`NUMBER`	The time, in 100ths of seconds, that the file was open
`MAXOPENFILES`	`NUMBER`	The number of concurrently open DISK files. This value is only present in rows where `TYPE`='`AGGREGATE`'
`BYTES`	`NUMBER`	The number of bytes read or written so far
`EFFECTIVE_BYTES_PER_SECOND`	`NUMBER`	The I/O rate that was achieved with this device during this backup
`IO_COUNT`	`NUMBER`	The number of I/Os that were performed to this file
`READY`	`NUMBER`	The number of asynchronous requests for which a buffer was immediately ready for use
`SHORT_WAITS`	`NUMBER`	The number of times that a buffer was not immediately available, but a buffer became available after doing a non-blocking poll for I/O completion
`SHORT_WAIT_TIME_TOTAL`	`NUMBER`	The total time, in 100ths of seconds, taken by non-blocking polls for I/O completion
`SHORT_WAIT_TIME_MAX`	`NUMBER`	The maximum time taken for a non-blocking poll for I/O completion, in 100ths of seconds
`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 100ths of seconds, 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 100ths of seconds