Update sections 3.4.3 and 3.4.4 to reflect current functionality

[Terry Ellison]

Section 3.4.3

We've just had a novice user complain (​Help: Recover data lost from revert to snapshot?) about the dangers of the "Revert to the current snapshot" checkbox. He checked this during his shutdown and lost a lot of work. His main complaints where (i) It isn't at all clear of the consequences of this; and (ii) there is no "Are you sure that you want to delete your current work in progress confirmation."

As to the second point the functionality here is consistent with the VBox GUI snapshot management (no confirmations either). My main issue here is that the screenshot given in 3.4.3 is out of date. The current dialogue box now includes a "Revert to the current snapshot" checkbox. This section in the User Guide should mention this and discuss what this is and what the consequences of checking it are.

Section 3.4.4

The note-box in this section states: "In order to prevent such data loss while still making use of the snapshot feature, it is possible to add a second hard drive in “write-through” mode using the VBoxManage interface and use it to store your data. As write-through hard drives are not included in snapshots, they remain unaltered when a machine is reverted."

This is sensible and what VBox should do, it is also factually incorrect. If you try this then VBox raises an error:

Cannot take a snapshot when there is a Writethrough hard disk attached ... E_FAIL (0x80004005)

[Technologov]

This wish may need some changes for VBox 3.1

-Technologov