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Hey Virtualbox Community.

I'm setting up a new pc for a family friend who has a nasty habit of clicking on every ad that pops up on his screen, forcing me to rebuild his pc every 3 months ( the gentlemen in question is in his 70's ). I'm using fedora 20 as the host with Windows XP SP3 as the guest environment. My plan is to setup is Windows guest environment and then take a snapshot so in the future if he messes up his Windows machine, I can simply restore to the snapshot and he is back in business.

Now the question: user has a number of personal files that need to be maintained . . . if I store his my documents folder in a shared folder with the host o/s, will those files be maintained when a snapshot is restored?

Thanks
The New Guy

No, shared folder contents are not included in a snapshot. In any case you should avoid snapshots - use real backups.

When a virtual disk is first created for a new virtual machine, it is considered as the base disk for the guest - data for the guest is read from and written to that disk image.

The differencing disk records changes sector-by-sector to the whole disk image, not changes to any file in the disk. VirtualBox does not know what file system is employed on the disk image and therefore can not access any individual file of/on the disk image; only the guest OS is aware of that information.

First SnapShot creates a differencing disk for read/write access while the base disk becomes read-only - as the guest modifies its data, the data is written to the differencing disk and the base disk is untouched.

Second SnapShot creates another, new, differencing disk for read/write access while the first differencing disk becomes read-only along with the base disk.

Subsequent SnapShots create additional differencing disks, with the preceding differencing disk joining the hierarchy (pecking order/chain) of read-only disks.

Keep in mind that access to/from the virtual disks is sector-by-sector, not file-by-file.

When the guest requests that a sector be read, the latest SnapShot is read first. If the sector is not found there (Sector-Not-Found is returned), the next SnapShot in the chain (youngest to oldest) is read, until the base virtual disk is reached. Then the sector on/in the base virtual disk is either read or Sector-Not-Found is returned.