OMV as VM has much higher cpu usage on samba and nfs transfers

  • Hi,

    I recently brought to life an old PC for testing purposes and I've been playing around with OMV and virtualization.

    When installing OMV as VM it shows a much higher cpu usage on the smbd and nfsd when copying files over the (local) network.


    - CPU: Intel Core 2 Quad Q9550 (4 cores, supports virtualization)

    - RAM: 4GB

    - 1 SSD for system

    - 2 HDD raid1 (mdadm) for data

    - 1 gigabit ethernet port

    With OMV installed natively, when transferring a large file from another PC on the LAN to a samba share on OMV, the CPU usage for smbd is about 50%. If using NFS, CPU usage for nfsd is close to 50% as well.

    Data transfer rate is about 115-117 MB/s (that's megabytes per second, which is very close to the gigabit ethernet limit).

    I then installed Proxmox on the same computer and OMV as a VM. Data HDD's passthrough with virtio-scsi, raid assembled with mdadm on OMV.

    All 4 cores and RAM made available for the VM.

    Data transfer rate was the same, but CPU usage for smbd was at 100%. Same result with NFS.

    I also tried to use OMV as host and OMV on a VM (created using cockpit-machines). Similar results.

    My first thought was that cpu virtualization was not being very efficient, but I ran sysbench cpu benchmark on both host and VM with similar results.

    Any ideas why this is happening?

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