#Snapshots, suspend and clones
Three ways to keep a machine's state, which save different things.
| Saves | Machine afterwards | Lives in | |
|---|---|---|---|
| Pause | Nothing: the guest's CPUs stop | Still running, frozen in memory | memory |
| Suspend | Memory | Off; the next start resumes exactly where it was | suspended.vzvmsave |
| Snapshot | Disks and firmware state, plus memory if taken while running | Unchanged | snapshots/<id>/ |
| Clone | A whole new machine | Unchanged | a new .vista folder |
#Snapshots
On the Snapshots tab, name a snapshot (or leave it blank for "Snapshot N") and choose Take Snapshot. In a machine's window it's Machine → Take Snapshot; in Vista's menu bar it's Machine → Take Snapshot (⇧⌘S).
Snapshots are copy-on-write. On an APFS volume (every Mac's internal
disk), Vista clones the machine's files with clonefile: a snapshot of a
64 GB disk is made in milliseconds and takes no space at first. It costs
space only as the machine writes afterwards, roughly the amount it changes.
On a volume without APFS, snapshots are full copies.
Snapshots of a running machine include its memory. Vista pauses the guest for a moment, writes its memory into the snapshot, clones the disks and resumes. Such snapshots are marked With memory. Some hardware configurations can't have their memory saved; Vista says so, and you can snapshot them while they're off.
#Reverting
Revert puts the machine back exactly as the snapshot found it, discarding everything since. A running machine is stopped first (Vista asks). Reverting to a snapshot with memory leaves the machine suspended at that moment: Start resumes into it, apps and all.
The machine's configuration is reverted too, since the memory only makes sense with the hardware it was saved with.
#Deleting
Deleting a snapshot frees the space only it was using. The machine isn't affected. Agents can also rename snapshots.
#Suspend
Suspend (header button, the machine window's Machine menu, or closing the machine's window) writes the guest's memory to the machine's folder and quits its process. Start — now labelled Resume — restores it in seconds.
The saved memory is used once. If you change the machine's hardware while it's
suspended, the saved memory no longer fits and the next start is a fresh boot,
as if the power had been cut; Vista logs that in machine.log.
#Clones
Clone (Overview tab) makes a complete copy of a stopped machine next to it, named "name copy". Like snapshots it's a copy-on-write clone: instant, and free until either machine changes.
The clone is a different machine, not a twin: it gets a new id, a new MAC address (so a different IP address) and a new platform identity, which the guest sees as different hardware. Snapshots aren't copied. A suspended machine has to be resumed and shut down before it can be cloned.