2 Replies Latest reply: Dec 19, 2012 3:11 AM by Ravinder Rathi-Oracle RSS

    EM Alert: Critical: Metrics "Global Cache Average Current Get Time" is at X

    dba-india
      I frequently get this notification email alert from the enterprise manager. What does this mean and should I ignore it or work on it?

      Name=<sid>_<instancename>
      Type=Database Instance
      Host=<servername>.<domainname>
      Metric=Global Cache Average Current Block Request Time (centi-seconds)
      Timestamp=Jan 27, 2009 9:27:20 PM GST
      Severity=Critical
      Message=Metrics "Global Cache Average Current Get Time" is at 1.46154
      Rule Name=XXProd
      Rule Owner=SYS

      masamimalik@yahoo.com
        • 1. Re: EM Alert: Critical: Metrics "Global Cache Average Current Get Time" is at X
          413311
          those metrics shows the effect of accessing blocks in the global cache and maintaining cache coherency.

          basically, the response time for Cache Fusion transfers is determined by the messaging time and
          processing time imposed by the physical interconnect components, the IPC protocol, and the
          GCS protocol.

          therefore, Inter-Instance performance issues can be caused by:

          1) Under configured network settings at the OS
          2) dropped packets,retransmits, or cyclic redundancy check errors (CRC)
          3) large number of processes in the run queue waiting for CPU
          4) high value for the DB_FILE_MULTIBLOCK_READ_COUNT

          Note also that poor SQL or bad optimization paths can cause additional block gets via the interconnect, just as not using ASSM for Locally Managed Tablespaces, or not using CACHE NOORDER for sequence, ...
          • 2. Re: EM Alert: Critical: Metrics "Global Cache Average Current Get Time" is at X
            Ravinder Rathi-Oracle
            This message is reporting metrics on the average amount of time it takes an instance to obtain a current copy of a data block via the cluster interconnect from another instance in the cluster. By default, Any block transfers across the interconnect would ideally be performed in less than 10ms(i.e 1 centi seconds).


            METRIC_NAME is "GC_AVG_CR_GET_TIME" Refer the below URL for the same:

            http://docs.oracle.com/cd/B19306_01/appdev.102/b14258/d_salt.htm


            If the frequency of these alerts are very minimal and no Performance issue reported, we can ignore this. Any performance issue is reported along with these Grid/OEM alerts, please consider investigating the issue at Network/Interconnect level.

            Edited by: 977730 on Dec 19, 2012 1:09 AM