1 Description
You can set the MAX_IOPS initialization parameter and the MAX_MBPS initialization parameter to limit the disk I/O generated by a PDB.
Restricted mainly to the PDB I / O, to control the overall performance of CDB, can ensure sufficient PDB other I / O resources are available.
A large amount of disk I/O can cause poor performance. Several factors can result in excess disk I/O, such as poorly designed SQL or index and table scans in high-volume transactions. If one PDB is generating a large amount of disk I/O, then it can degrade the performance of other PDBs in the same CDB.
- The MAX_IOPS initialization parameter limits the number of I/O operations for each second. --限制I/O次数
- The MAX_MBPS initialization parameter limits the megabytes for I / O operations for each second - to limit I / O bytes.
Note: If you set these two parameters in the CDB level, it will limit the CDB in all PDB I / O
1.1 setting mode
SQL> ALTER SYSTEM SET MAX_IOPS = 1000 SCOPE = BOTH;
System altered.
SQL> ALTER SYSTEM SET MAX_MBPS = 5 SCOPE = BOTH;
System altered.
1.2 Check PDB I / O Usage
You can use the DBA_HIST_RSRC_PDB_METRIC view to calculate a reasonable I/O limit for a PDB. Consider the values in the following columns when calculating a limit: IOPS, IOMBPS, IOPS_THROTTLE_EXEMPT, and IOMBPS_THROTTLE_EXEMPT. The “rsmgr:io rate limit” wait event indicates that a limit was reached.
DBA_HIST_RSRC_PDB_METRIC view may be used to calculate a reasonable PDB I / O limit. When calculating the limit, consider the following values: IOPS, IOMBPS, IOPS_THROTTLE_EXEMPT and IOMBPS_THROTTLE_EXEMPT. "Rsmgr: io rate limit" wait event indicates achieve I / O limitations.
For more information, please see the official document:
http://docs.oracle.com/database/122/ADMIN/using-oracle-resource-manager-for-pdbs-with-sql-plus.htm#ADMIN13789