Honor Guest IDE/SATA Flush Requests

Issue

VirtualBox ignores IDE/SATA disk flush requests.

Cause

This is by design. To improve performance VirtualBox ignores these requests. This can create an issue with filesystems that do not have fsck-like tools (ZFS is an example) create a situation where the on disk information is inconsistent due to data held in RAM.

Solution

To enable flushing for IDE disks, issue the following command:

VBoxManage setextradata VMNAME
      "VBoxInternal/Devices/piix3ide/0/LUN#[x]/Config/IgnoreFlush" 0

The value [x] that selects the disk is 0 for the master device on the first channel, 1 for the slave device on the first channel, 2 for the master device on the second channel or 3 for the master device on the second channel.

To enable flushing for SATA disks, issue the following command:

VBoxManage setextradata VMNAME
      "VBoxInternal/Devices/ahci/0/LUN#[x]/Config/IgnoreFlush" 0

The value [x] that selects the disk can be a value between 0 and 29.

Reference

http://www.virtualbox.org/manual/UserManual.html#id2499944