The advanced VMkernel.Boot.isPerFileSchedModelActive parameter controls the per file I/O scheduling mechanism. The mechanism is enabled by default.


  1. Browse to the host in the vSphere Web Client navigator.
  2. Click the Manage tab, and click Settings.
  3. Under System, click Advanced System Settings.
  4. Under Advanced System Settings, select the VMkernel.Boot.isPerFileSchedModelActive parameter and click the Edit icon.
  5. Select one of the following options:
    • To disable the per file scheduling mechanism, change the value to No.


      After you turn off the per file I/O scheduling model, your host reverts to a legacy scheduling mechanism that uses a single I/O queue. The host maintains the single I/O queue for each virtual machine and storage device pair. All I/Os between the virtual machine and its virtual disks stored on the storage device are moved into this queue. As a result, I/Os from different virtual disks might interfere with each other in sharing the bandwidth and affect each others performance.

    • To reenable the per file scheduling mechanism, change the value to Yes.

  6. Reboot the host for the changes to take effect.