6.3.10 Monitoring Grid Disks

Grid disk metrics provide information about the I/O load for grid disks, such as the number of large blocks read from a grid disk.

Grid disk metrics are identified in the METRICCURRENT, METRICDEFINITION, and METRICHISTORY objects as having objectType=GRIDDISK.

The grid disk 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 is determined by subtracting values from different collectionTime periods. For rate metrics, the time period for the metric value is over the previous minute.

Example 6-13 Displaying Grid Disk Metric Definitions

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

CellCLI> LIST METRICDEFINITION ATTRIBUTES NAME,DESCRIPTION WHERE OBJECTTYPE = GRIDDISK
         GD_BY_FC_DIRTY                  "Number of unflushed megabytes cached in FLASHCACHE for a grid disk"
         GD_IO_BY_R_LG                   "Number of megabytes read in large blocks from a grid disk"
         GD_IO_BY_R_LG_SEC               "Number of megabytes read in large blocks per second from a grid disk"
         GD_IO_BY_R_SCRUB                "Number of megabytes read from a grid disk by the scrubbing job"
         GD_IO_BY_R_SCRUB_SEC            "Number of megabytes read per second from a grid disk by the scrubbing job"
         GD_IO_BY_R_SM                   "Number of megabytes read in small blocks from a grid disk"
         GD_IO_BY_R_SM_SEC               "Number of megabytes read in small blocks per second from a grid disk"
         GD_IO_BY_W_LG                   "Number of megabytes written in large blocks to a grid disk"
         GD_IO_BY_W_LG_SEC               "Number of megabytes written in large blocks per second to a grid disk"
         GD_IO_BY_W_SM                   "Number of megabytes written in small blocks to a grid disk"
         GD_IO_BY_W_SM_SEC               "Number of megabytes written in small blocks per second to a grid disk"
         GD_IO_ERRS                      "Number of IO errors on a grid disk"
         GD_IO_ERRS_MIN                  "Number of IO errors on a grid disk per minute"
         GD_IO_ERRS_SCRUB                "Number of IO errors hit by the scrubbing job on a grid disk"
         GD_IO_RQ_R_LG                   "Number of requests to read large blocks from a grid disk"
         GD_IO_RQ_R_LG_SEC               "Number of requests to read large blocks per second from a grid disk"
         GD_IO_RQ_R_SCRUB                "Number of requests to read from a grid disk by the scrubbing job"
         GD_IO_RQ_R_SCRUB_SEC            "Number of requests to read per second from a grid disk by the scrubbing job"
         GD_IO_RQ_R_SM                   "Number of requests to read small blocks from a grid disk"
         GD_IO_RQ_R_SM_SEC               "Number of requests to read small blocks per second from a grid disk"
         GD_IO_RQ_W_LG                   "Number of requests to write large blocks to a grid disk"
         GD_IO_RQ_W_LG_SEC               "Number of requests to write large blocks per second to a grid disk"
         GD_IO_RQ_W_SM                   "Number of requests to write small blocks to a grid disk"
         GD_IO_RQ_W_SM_SEC               "Number of requests to write small blocks per second to a grid disk"
         GD_NVM_READ_RETRIES             "Number of read retries for a non-volatile memory (NVM) grid disk"
         GD_SP_BY_ALLOCATED              "Allocated physical space for grid disk in bytes"
         GD_SP_IO_BY_PARTIAL             "Bytes returned by partial IOs"
         GD_SP_IO_BY_PARTIAL_SEC         "Bytes returned by partial IOs per second"
         GD_SP_IO_BY_REDIRECTED          "Sparse bytes redirected to original data block"
         GD_SP_IO_BY_REDIRECTED_SEC      "Sparse bytes redirected to original data block per second"
         GD_SP_IO_RQ_PARTIAL             "Number of IO requests that returned partial data"
         GD_SP_IO_RQ_PARTIAL_SEC         "Number of IO requests that returned partial data per second"
         GD_SP_PRCT_ALLOCATED            "Allocated physical space for grid disk by percentage"

Note the following additional details:

  • GD_SP_PRCT_ALLOCATED tracks the allocated physical space for the grid disk, and is presented as a percentage. By default, a warning alert is generated when space usage is more than 95%, and a critical alert is generated when space usage reaches 99%. To lower the space usage, you can increase the size of the grid disk, or drop some of the data on the grid disk.

Parent topic: Monitoring Oracle Exadata System Software Components