Database Reference
In-Depth Information
is to dismount the diskgroup and mount the group in restricted mode; however, this would potentially cause the
database to be unable to access disks, thus causing outage. Like most features, a correct balance between the number
of processes and time is required in order to manage resources and allow business to continue without downtime.
V$IOSTAT_FILE
This view displays information regarding the disk I/O statistics of database files. Statistics are listed for each data file
and temp file; however, for other types of files, such as archive logs and backup sets, statistics are consolidated into
one entry. The output illustrates that the operations have been small, quick-read options, indicated by the
small_read_megabytes column, with multi-block reads indicated by the large_read_megabytes column. The last
column, large_read_servicetime, lists the service time for multi-block read requests.
Script: MVRACPDnTap_iostat.sql
SELECT file_no,
filetype_name,
small_read_megabytes,
large_read_megabytes,
large_read_servicetime
FROM v$iostat_file;
File Small Read Large Read Large Read
# File Type (Megabytes) (Megabytes) Service Time
----- -------------------- ----------- ------------ -------------
0 Other 35 2349 44279
0 Control File 20219 284 2822
0 Log File 1 42546 0
0 Archive Log 0 27962 184702
0 Data File Backup 0 0 0
0 Data File Incrementa 0 0 0
0 Archive Log Backup 0 0 0
0 Data File Copy 0 0 0
0 Flashback Log 0 0 0
0 Data Pump Dump File 0 0 0
1 Data File 144 275 3606
1 Temp File 388 364 0
2 Data File 287 3 154
2 Temp File 3271 2884 95
3 Data File 0 0 0
3 Temp File 2969 3102 40
4 Data File 3 0 0
4 Temp File 973 2089 15
5 Data File 0 0 0
5 Temp File 1091 1020 104
6 Temp File 540 1690 62
7 Temp File 1118 1574 107
8 Temp File 1130 1068 14
9 Temp File 549 1207 43
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