When you select a custom configuration on a Linux host, you can use the New Virtual Machine wizard to configure normal or independent mode for a disk.

In normal mode, disks are included in snapshots that you take of the virtual machine. If you do not want data on the disk to be recorded when you take a snapshot of the virtual machine, configure the disk to be independent.

If you configure a disk to be independent, you can further specify whether changes you make to the disk are to persist or be discarded when you power off the virtual machine or restore a snapshot.

You can also exclude virtual disks from snapshots by modifying virtual machine settings.