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 Category Metrics

6.3.8.3.4 Monitoring IORM with Category Metrics

Category metrics provide information about the I/O load from each category specified in the current IORM category plan.

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

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

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.

Example 6-11 Displaying Category Metric Definitions

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

CellCLI> LIST METRICDEFINITION ATTRIBUTES NAME,DESCRIPTION WHERE OBJECTTYPE = IORM_CATEGORY
         CT_FC_IO_BY_SEC         "Number of megabytes of I/O per second for this category to flash cache"
         CT_FC_IO_RQ             "Number of IO requests issued by an IORM category to flash cache"
         CT_FC_IO_RQ_LG          "Number of large IO requests issued by an IORM category to flash cache"
         CT_FC_IO_RQ_LG_SEC      "Number of large IO requests issued by an IORM category to flash cache per second"
         CT_FC_IO_RQ_SEC         "Number of IO requests issued by an IORM category to flash cache per second"
         CT_FC_IO_RQ_SM          "Number of small IO requests issued by an IORM category to flash cache"
         CT_FC_IO_RQ_SM_SEC      "Number of small IO requests issued by an IORM category to flash cache per second"
         CT_FD_IO_BY_SEC         "Number of megabytes of I/O per second for this category to flash disks"
         CT_FD_IO_LOAD           "Average I/O load from this category for flash disks"
         CT_FD_IO_RQ_LG          "Number of large IO requests issued by an IORM category to flash disks"
         CT_FD_IO_RQ_LG_SEC      "Number of large IO requests issued by an IORM category to flash disks per second"
         CT_FD_IO_RQ_SM          "Number of small IO requests issued by an IORM category to flash disks"
         CT_FD_IO_RQ_SM_SEC      "Number of small IO requests issued by an IORM category to flash disks per second"
         CT_FD_IO_TM             "The cumulative latency of reading or writing blocks for this category from flash disks"
         CT_FD_IO_TM_LG          "The cumulative latency of reading or writing large blocks for this category from flash disks"
         CT_FD_IO_TM_LG_RQ       "The rate which is the average latency of reading or writing large blocks per request for this category from flash disks"
         CT_FD_IO_TM_RQ          "The rate which is the average latency of reading or writing blocks per request for this category from flash disks"
         CT_FD_IO_TM_SM          "The cumulative latency of reading or writing small blocks for this category from flash disks"
         CT_FD_IO_TM_SM_RQ       "The rate which is the average latency of reading or writing small blocks per request for this category from flash disks"
         CT_FD_IO_UTIL           "Percentage of flash resources utilized by this category"
         CT_FD_IO_UTIL_LG        "Percentage of flash resources utilized by large requests from this category"
         CT_FD_IO_UTIL_SM        "Percentage of flash resources utilized by small requests from this category"
         CT_FD_IO_WT_LG          "IORM wait time for large IO requests issued to flash disks by an IORM category"
         CT_FD_IO_WT_LG_RQ       "Average IORM wait time per request for large IO requests issued to flash disks by an IORM category"
         CT_FD_IO_WT_SM          "IORM wait time for small IO requests issued to flash disks by an IORM category"
         CT_FD_IO_WT_SM_RQ       "Average IORM wait time per request for small IO requests issued to flash disks by an IORM category"
         CT_IO_BY_SEC            "Number of megabytes of I/O per second for this category to hard disks"
         CT_IO_LOAD              "Average I/O load from this category for hard disks"
         CT_IO_RQ_LG             "Number of large IO requests issued by an IORM category to hard disks"
         CT_IO_RQ_LG_SEC         "Number of large IO requests issued by an IORM category to hard disks per second"
         CT_IO_RQ_SM             "Number of small IO requests issued by an IORM category to hard disks"
         CT_IO_RQ_SM_SEC         "Number of small IO requests issued by an IORM category to hard disks per second"
         CT_IO_TM_LG             "The cumulative latency of reading or writing large blocks for this category from hard disks"
         CT_IO_TM_LG_RQ          "The rate which is the average latency of reading or writing large blocks per request for this category from hard disks"
         CT_IO_TM_SM             "The cumulative latency of reading or writing small blocks for this category from hard disks"
         CT_IO_TM_SM_RQ          "The rate which is the average latency of reading or writing small blocks per request for this category from hard disks"
         CT_IO_UTIL_LG           "Percentage of disk resources utilized by large requests from this category"
         CT_IO_UTIL_SM           "Percentage of disk resources utilized by small requests from this category"
         CT_IO_WT_LG             "IORM wait time for large IO requests issued to hard disks by an IORM category"
         CT_IO_WT_LG_RQ          "Average IORM wait time per request for large IO requests issued to hard disks by an IORM category"
         CT_IO_WT_SM             "IORM wait time for small IO requests issued to hard disks by an IORM category"
         CT_IO_WT_SM_RQ          "Average IORM wait time per request for small IO requests issued to hard disks by an IORM category"

Note the following additional details:

  • 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.

  • The unit of measurement for the wait metrics is milliseconds. The wait metrics have metric names starting with CD_IO_WT_.

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

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

  • To list the category metric history for an interdatabase plan, use the following CellCLI command:

    CellCLI> LIST METRICHISTORY WHERE objectType = 'IORM_CATEGORY' AND metricValue != 0 ATTRIBUTES name, metricObjectName, metricValue, collectionTime

  • Category metrics are also provided for the following internally-generated and automatically-managed categories:

    • _ASM_: Oracle ASM-related I/Os

    • _ORACLE_BG_CATEGORY_: High-priority I/Os issued by Oracle Database background processes

    • _ORACLE_MEDPRIBG_CATEGORY_: Medium-priority I/Os issued by Oracle Database background processes

    • _ORACLE_LOWPRIBG_CATEGORY_: Low-priority I/Os issued by Oracle Database background processes

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