VMware vSphere

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  • 1.  maximum memory for virtual machine possible

    Posted Jan 22, 2023 02:05 PM

    Hello,

    If I have 2 esxi hosts in cluster with 1TB memory in each host. so total cluster memory 2TB

    If I want to build a VM with memory 1TB and want to power it on, will esxi or vcenter will allow me to power on a VM having memory equal to all total memory of the esxi hosts i.e. 1TB ?

    Incase any additional details are needed, please let me know



  • 2.  RE: maximum memory for virtual machine possible

    Posted Jan 22, 2023 11:48 PM

    you should be able to start your VM normally.

    But which ESXi version we are discussing here?

    Remember about VMware Tools, VM Hardware Version and from Cluster level configuring Datastore for SWAP Memory. 



  • 3.  RE: maximum memory for virtual machine possible

    Posted Jan 23, 2023 06:45 AM

    it is vsphere 7 U3, how a VM will be able to power on when the host on which it is residing having memory equal to VM, the OS we will be installing is going to be RHEL 7.9



  • 4.  RE: maximum memory for virtual machine possible

    Posted Jan 23, 2023 07:21 AM

    Because you can configure and starting a VM with more vMem as the Host have phys. Memory. Reason is quite simple because ESXi uses a swap file for that which of curse kills the performance but it will "run".  There s also memory compression, Ballooning and TpS.

    There is a config max.

    https://configmax.esp.vmware.com/guest?vmwareproduct=vSphere&release=vSphere%207.0&categories=1-0

    Regards,
    J.B

     



  • 5.  RE: maximum memory for virtual machine possible

    Posted Jan 23, 2023 10:14 AM

    This is a uncommon spec because applications in a vm with 1-2TB amount of memory needed typically run with VMware validated design support. That's the first point in a design finding phase. Your hardware must be able to handle I/O. Overcommitting vm memory and reserving a part of it, yes, this works, but the hardware should be rugged enough for the application. See application specs about VMware prerequisites in detail.