NEC N8800-155F User Manual page 107

IMPORTANT:
The time required for synchronization varies depending on the partition
size on the disk. For a 40GB partition, it takes about 50 minutes.
Setting dual disk configuration may not complete if you reboot the
system during the synchronization. Do not reboot the system before
synchronization process completes.
If the system stops by terminating Windows improperly such as pressing
the power button, the whole disk area already synchronized will be
resynchronized after rebooting the system.
Windows Setup 4-53