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  • Clustering in Vmware 4.1

    I am using Vmware 4.1.
    If I create a cluster of two physical machines, can I create a virtual machine that is larger than one physical host?
    If one of the physical hosts crashes will a connection to the server be lost?
    I understand Vmotion can be used to migrate vms from one physical host to another but can clustering be used for HA?

    For example:
    Physical server 1 with 1 processor and physical server 2 with 1 processor are assigned to cluster 1.
    Create virtual machine 1 on cluster 1 with 2 processors.
    Install an application on virtual machine 1 that writes transactions to disk. Crash physical server 1.
    Would virtual machine crash? Would application crash?

    I've read the vmware HA overview.

    But is there documentation I can read on clustering regarding the functionality I'm researching?

    Thanks.

  • #2
    Re: Clustering in Vmware 4.1

    You might wanna read this:
    http://www.yellow-bricks.com/vmware-...ility-deepdiv/
    Marcel
    Technical Consultant
    Netherlands
    http://www.phetios.com
    http://blog.nessus.nl

    MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
    "No matter how secure, there is always the human factor."

    "Enjoy life today, tomorrow may never come."
    "If you're going through hell, keep going. ~Winston Churchill"

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    • #3
      Re: Clustering in Vmware 4.1

      Thanks for the detailed document.
      I also found this to be an interested read:
      Oracle_Databases_on_VMware_-_High_Availability_Guidelines.pdf
      Just google for it it's on Vmware website.

      So basically you can't have hot failover for databases on VMware, only cold failover. The virtual machine woudl have to be restarted.

      I still can't see if I can have a virtual machines processor number higher than any one physical machines processor.
      (ie) Can I use VM to scale out like Oracle RAC?

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      • #4
        Re: Clustering in Vmware 4.1

        The document from yellowbricks discbribe also about slot sizes, which is important for HA en failover. Read that part carefully since this is I think the answer you are looking for.

        Note, HA is not based on application level, however it's intended for host failure. Where you might want to look at is probably OS clustering or FT if you can fit in the requirements.

        On VMware you can have assign multiple vCPU to any VM. However keep in mind this can degredate performance when you would do to many VMs. Google for CPU ready time to find more about possible performance degradations.
        You also might want to read this:
        http://www.vmware.com/pdf/Perf_Best_...vSphere4.1.pdf

        Oh, about multiple vCPUs, see the configuration maximums of vSphere 4.1
        http://www.vmware.com/pdf/vsphere4/r...config_max.pdf
        Marcel
        Technical Consultant
        Netherlands
        http://www.phetios.com
        http://blog.nessus.nl

        MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
        "No matter how secure, there is always the human factor."

        "Enjoy life today, tomorrow may never come."
        "If you're going through hell, keep going. ~Winston Churchill"

        Comment


        • #5
          Re: Clustering in Vmware 4.1

          The physical host on which a VM runs defines the maximum number of virtual CPU cores a VM can have. So if you have a physical server with 2 x quad-core CPUs you could allocate up to a total of 8 virtual CPU cores to VMs on that host. If you did that though, and you had another physical host with only 1 x quad-core CPU, you would not be able to migrate that VM to that host, nor would it failover with HA.
          VCP2 / VCP3 / VCP4 / VCP 5 / VCAP-DCA4 / VCI / vExpert 2010-2012

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