1. User's Guide
  2. Monitoring Exadata
  3. Monitoring Oracle Exadata System Software Components
  4. Monitoring I/O Resource Management (IORM)
  5. Monitoring I/O Resource Management (IORM) Using Exadata Metrics
  6. Monitoring IORM with Database Metrics

6.3.8.3.1 Monitoring IORM with Database Metrics

Database metrics provide information about the I/O load from each database listed in the IORM interdatabase plan.

Database metrics are identified in the METRICCURRENT, METRICDEFINITION, and METRICHISTORY objects as having objectType=IORM_DATABASE.

Example 6-8 Displaying Category Metric Definitions

This example shows how to display the database metric definitions that are available in the Oracle Exadata System Software. 

CellCLI> LIST METRICDEFINITION ATTRIBUTES NAME,DESCRIPTION WHERE OBJECTTYPE = IORM_DATABASE
         DB_FC_BY_ALLOCATED      "Number of megabytes allocated in flash cache for this database"
         DB_FC_IO_BY_SEC         "Number of megabytes of I/O per second for this database to flash cache"
         DB_FC_IO_RQ             "Number of IO requests issued by a database to flash cache"
         DB_FC_IO_RQ_LG          "Number of large IO requests issued by a database to flash cache"
         DB_FC_IO_RQ_LG_SEC      "Number of large IO requests issued by a database to flash cache per second"
         DB_FC_IO_RQ_SEC         "Number of IO requests issued by a database to flash cache per second"
         DB_FC_IO_RQ_SM          "Number of small IO requests issued by a database to flash cache"
         DB_FC_IO_RQ_SM_SEC      "Number of small IO requests issued by a database to flash cache per second"
         DB_FD_IO_BY_SEC         "Number of megabytes of I/O per second for this database to flash disks"
         DB_FD_IO_LOAD           "Average I/O load from this database for flash disks"
         DB_FD_IO_RQ_LG          "Number of large IO requests issued by a database to flash disks"
         DB_FD_IO_RQ_LG_SEC      "Number of large IO requests issued by a database to flash disks per second"
         DB_FD_IO_RQ_SM          "Number of small IO requests issued by a database to flash disks"
         DB_FD_IO_RQ_SM_SEC      "Number of small IO requests issued by a database to flash disks per second"
         DB_FD_IO_TM             "The cumulative latency of reading or writing blocks by a database from flash disks"
         DB_FD_IO_TM_LG          "The cumulative latency of reading or writing large blocks by a database from flash disks"
         DB_FD_IO_TM_LG_RQ       "The rate which is the average latency of reading or writing large blocks per request by a database from flash disks"
         DB_FD_IO_TM_RQ          "The rate which is the average latency of reading or writing blocks per request by a database from flash disks"
         DB_FD_IO_TM_SM          "The cumulative latency of reading or writing small blocks by a database from flash disks"
         DB_FD_IO_TM_SM_RQ       "The rate which is the average latency of reading or writing small blocks per request by a database from flash disks"
         DB_FD_IO_UTIL           "Percentage of flash resources utilized by this database"
         DB_FD_IO_UTIL_LG        "Percentage of flash resources utilized by large requests from this database"
         DB_FD_IO_UTIL_SM        "Percentage of flash resources utilized by small requests from this database"
         DB_FD_IO_WT_LG          "IORM wait time for large IO requests issued to flash disks by a database"
         DB_FD_IO_WT_LG_RQ       "Average IORM wait time per request for large IO requests issued to flash disks by a database"
         DB_FD_IO_WT_SM          "IORM wait time for small IO requests issued to flash disks by a database"
         DB_FD_IO_WT_SM_RQ       "Average IORM wait time per request for small IO requests issued to flash disks by a database"
         DB_FL_IO_BY             "The number of MB written to the Flash Log"
         DB_FL_IO_BY_SEC         "The number of MB written per second to the Flash Log"
         DB_FL_IO_RQ             "The number of I/O requests issued to the Flash Log"
         DB_FL_IO_RQ_SEC         "The number of I/O requests per second issued to the Flash Log"
         DB_IO_BY_SEC            "Number of megabytes of I/O per second for this database to hard disks"
         DB_IO_LOAD              "Average I/O load from this database for hard disks"
         DB_IO_RQ_LG             "Number of large IO requests issued by a database to hard disks"
         DB_IO_RQ_LG_SEC         "Number of large IO requests issued by a database to hard disks per second"
         DB_IO_RQ_SM             "Number of small IO requests issued by a database to hard disks"
         DB_IO_RQ_SM_SEC         "Number of small IO requests issued by a database to hard disks per second"
         DB_IO_TM_LG             "The cumulative latency of reading or writing large blocks by a database from hard disks"
         DB_IO_TM_LG_RQ          "The rate which is the average latency of reading or writing large blocks per request by a database from hard disks"
         DB_IO_TM_SM             "The cumulative latency of reading or writing small blocks by a database from hard disks"
         DB_IO_TM_SM_RQ          "The rate which is the average latency of reading or writing small blocks per request by a  database from hard disks"
         DB_IO_UTIL_LG           "Percentage of disk resources utilized by large requests from this database"
         DB_IO_UTIL_SM           "Percentage of disk resources utilized by small requests from this database"
         DB_IO_WT_LG             "IORM wait time for large IO requests issued to hard disks by a database"
         DB_IO_WT_LG_RQ          "Average IORM wait time per request for large IO requests issued to hard disks by a database"
         DB_IO_WT_SM             "IORM wait time for small IO requests issued to hard disks by a database"
         DB_IO_WT_SM_RQ          "Average IORM wait time per request for small IO requests issued to hard disks by a database"
         DB_XRM_BY_ALLOCATED      "Number of megabytes allocated in XRMEM cache for this database"

Note the following additional details:

  • The database for the metric is specified by the metricObjectName attribute of the METRICCURRENT and METRICHISTORY objects.

  • For metrics that relate to I/O load (for example, DB_FD_IO_LOAD and DB_IO_LOAD), see the additional information relating to CD_IO_LOAD.

  • Starting with Oracle Exadata System Software release 19.1.0, if you configured ASM-scoped security for the Oracle Automatic Storage Management (Oracle ASM) cluster used by the database, then the database name is prefixed with the Oracle ASM cluster name.

  • For cumulative metrics, the metric value for a specific time period can be determined by subtracting values from different collectionTime periods.

  • For rate metrics, the time period for the metric value is over the previous minute.

  • In the metric descriptions, small I/O requests are less than or equal to 128 KB, and large I/O requests are larger than 128 KB.

  • All database cumulative metrics are reset to zero whenever a category, IORM, or any database resource plan is modified.

  • To list the database metric history for an inter-database plan, use the following CellCLI command: 

    CellCLI> LIST METRICHISTORY WHERE objectType = 'IORM_DATABASE' AND metricValue != 0 ATTRIBUTES name, metricObjectName, metricValue, collectionTime
  • For multitenant container databases (CDBs), the database metric observations include all of the I/Os associated with the database, including all of the associated pluggable databases (PDBs). For example, the value for DB_FC_IO_BY_SEC includes the sum of the PDB_FC_IO_BY_SEC values for all of the PDBs hosted by the CDB.

  • Observations for Oracle ASM and all other databases not listed in the interdatabase plan are grouped together using _OTHER_DATABASE_ as the metricObjectName value.

Parent topic: Monitoring I/O Resource Management (IORM) Using Exadata Metrics