Which two statements are about Unplanned Device Loss in a vSphere 5 environment?

Which two statements are about Unplanned Device Loss in a vSphere 5 environment? (Choose two)

A.
It is condition where an ESXi host determines a device loss has occurred that was not planned.

B.
Performing a storage rescan restores access to determine why device loss occurred.

C.
It is a condition where an ESXi host is unable to determine why device loss occurred.

D.
Performing a storage rescan removes the persistent information related to the device.

Explanation:

Page 132 from vsphere-esxi-vcenter-server-50-storage-guide.pdf

Unplanned Device Loss
Unplanned device loss is a condition that occurs when your ESXi host permanently loses connection to a storage device.
Problem
Although the ESXi host cannot determine the reason for a device loss, the host supports the loss detection. When the device becomes permanently unavailable, ESXi receives sense codes from storage arrays and recognizes that the device is permanently lost, not just temporarily unavailable. ESXi marks the device as not connected and a warning about the device being permanently unavailable appears in the VMkernel log file.
Cause
Typically, unplanned device loss is unintentional and can occur when a storage device is unmapped, removed, or its unique ID changes, or when there is an unrecoverable hardware error.
Solution
If you experience an unplanned device loss condition, you must unmount any related datastores and perform a storage rescan to remove the persistent information associated with the device. See the following topics:
* To verify the status of the device, see Check the Connection Status of a Storage Device, on page 132.
* To unmount a datastore, see Unmount VMFS or NFS Datastores, on page 128.
* To perform a rescan, see Perform Storage Rescan, on page 124.