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    Less RAM in VM than allocated RAM on host

    Scheduled Pinned Locked Moved Solved Compute
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    • A Offline
      aslbhr
      last edited by

      Hi ,

      I have installed "Oracle Linux Server release 7.9" as guest by allocating 8GB RAM

      Capture.JPG

      When i logged into VM, i see that fewer memory is available

      [root@oelrac01n01 etc]#  grep MemTotal /proc/meminfo
      MemTotal:        7839920 kB
      

      param list on host is following

      [15:43 xcp-ng-duexgxtk etc]#  xe vm-param-list uuid=1fb2e6c5-6210-92ca-f547-e1c9bbac5596| grep memory
                               memory-actual ( RO): 8589934592
                               memory-target ( RO): 0
                             memory-overhead ( RO): 77594624
                           memory-static-max ( RW): 8589934592
                          memory-dynamic-max ( RW): 8589934592
                          memory-dynamic-min ( RW): 8589934592
                           memory-static-min ( RW): 134217728
                             recommendations ( RO): <restrictions><restriction field="memory-static-max" max="137438953472"/><restriction field="vcpus-max" max="32"/><restriction field="has-vendor-device" value="false"/><restriction field="supports-bios" value="yes"/><restriction field="supports-uefi" value="yes"/><restriction field="supports-secure-boot" value="yes"/><restriction max="255" property="number-of-vbds"/><restriction max="7" property="number-of-vifs"/></restrictions>
                                      memory (MRO):
      

      any idea why i have fewer memory in VM?

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      • olivierlambertO Offline
        olivierlambert Vates 🪐 Co-Founder CEO
        last edited by

        That memory is needed because of:

        • shadow copies of page tables, needed during migration or if hardware assisted paging is not available
        • video RAM for the virtual graphics card
        • records in the hypervisor describing the VM and the vCPUs
        A 1 Reply Last reply Reply Quote 0
        • olivierlambertO Offline
          olivierlambert Vates 🪐 Co-Founder CEO
          last edited by

          Because you have 74MiB of memory overhead, as visible in memory-overhead value.

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          • A Offline
            aslbhr
            last edited by

            Hi Oliver ,

            Thank you for answer. What is memory-overhead and why it is 74 Mib

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            • olivierlambertO Offline
              olivierlambert Vates 🪐 Co-Founder CEO
              last edited by

              That memory is needed because of:

              • shadow copies of page tables, needed during migration or if hardware assisted paging is not available
              • video RAM for the virtual graphics card
              • records in the hypervisor describing the VM and the vCPUs
              A 1 Reply Last reply Reply Quote 0
              • A Offline
                aslbhr @olivierlambert
                last edited by

                This post is deleted!
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                • A Offline
                  aslbhr
                  last edited by

                  can video RAM for the virtual graphics card be set /decreased ?

                  Thank you.

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                  • olivierlambertO Offline
                    olivierlambert Vates 🪐 Co-Founder CEO
                    last edited by

                    Check the Advanced tab of the VM

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                    • A Offline
                      aslbhr
                      last edited by

                      which one ?

                      Capture.JPG

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                      • olivierlambertO Offline
                        olivierlambert Vates 🪐 Co-Founder CEO
                        last edited by

                        In Xen Orchestra, XCP-ng Center isn't a supported client for XCP-ng.

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