1 Reply Latest reply on Jul 26, 2010 8:54 AM by J1mbo

    Oracle 11g on Win2k8 - 100% guest CPU, 15% host

    J1mbo Virtuoso

      I have an odd issue with a new install of Oracle 11g on Windows 2008 running on ESX U1.



      - Win2k8, 8GB RAM, 2 vCPU

      - Disk 1 - 40GB, thick-provisioned, LSI-SAS controller

      - Disk 2 - 250GB, thick-provisioned, paravirtual controller


      Host is Dell R610, 2x X5570, hyper-threading enabled, 48GB RAM, no other guests running for this test.


      Oracle was running perfectly - calibrate_io showing 6500 iops (EqualLogic storage).


      Now running calibrate_io, the Oracle process is using 100% CPU resource as viewed from Windows task manager, but viewed from vCentre the VM CPU usage is perhaps 15 to 25% only.  Eventually it reports 200 IOPS.


      I reduced to 1 vCPU, but the same happens.


      Running calc.exe to calculate 12345678! reports 100% CPU in Task Manager and 100% in vCentre as would be expected.


      Last job to run normally was a large(ish) import.  The VM has a snapshot (which because of the import is now 60GB).  I have moved it between hosts and datastores with no differences.



      Any help would be very greatfully received.


      Thanks in advance!

        • 1. Re: Oracle 11g on Win2k8 - 100% guest CPU, 15% host
          J1mbo Virtuoso

          For the record, the issue turned out to be just the snapshot, which was about 60GB existed due to a database import.  Once consolidated the performance returned to normal.


          The job impacted the performance of the calibrate_io task seemingly because the processing overhead firstly reduced the CPU allocation to the guest (hence the 100% guest level/15% host level thing) but secondly added great latency.  Since the calibrate_io process was running with a 20ms latency limit specified, the queue wasn't being ramped at all hence the rubbish throughput.