Which file format is used for VM snapshots in vSphere?

In vSphere, the file format used for virtual machine (VM) snapshots is indeed the VMSN format. When a snapshot is created, vSphere captures the state of the virtual machine, including its disk, memory, and device status, at that particular moment. The VMSN file holds this memory state, allowing for the VM to be reverted back to this point in time.

The snapshot process is integral for backup and recovery scenarios, enabling administrators to save the entire state of a VM. This means that when you revert to a snapshot, the VM can be restored to how it was at the moment the snapshot was taken, including the contents of its memory. This functionality is pivotal for testing, as it allows an administrator to rollback changes that may have negatively impacted the system.

Other file formats mentioned, like VMDK (used for virtual disk files), VMSWAP (used to store swap data for VMs), and VMSD (which contains metadata about snapshots), serve different roles within the virtual infrastructure management but do not specifically hold the snapshot memory states. Understanding what each file type does helps clarify their specific use cases and importance within VMware environments.