After a host reboot

A host reboot stops everything. When Virtainer Free starts again it rebuilds machines from what it recorded before, so a reboot is an interruption rather than a rebuild.

What comes back

Before the reboot	After
Running	Rebuilt and started, keeping its MAC address, so the guest keeps the same IP
Created but never booted	Rebuilt, not started, ready to boot
Powered off	Left off
Stopped by you	Never started automatically

A reboot is not a power cut. Before the host goes down, Virtainer Free asks every running machine to shut itself down and waits, up to a total of about a minute. A machine that has not stopped within roughly twenty seconds of its own request is taken down without waiting further, so a guest still writing when that budget ran out is the one case where its filesystem may need checking afterwards. Machines that halted cleanly come back as the table above describes.

Turning off VM autostart in Settings changes the first row only: machines that were running come back stopped, and you start them when you are ready. Everything else behaves the same.

Restarting Virtainer Free is not the same as rebooting the host

Upgrading or restarting Virtainer Free leaves running machines alone. Only a host reboot tears them down and requires this recovery.

Checking what happened

The agent’s log records the startup reconcile and recovery passes, including how many machines were attempted, recovered, failed, or skipped. Read it in Logs and diagnostics, under Run log.

When something did not come back

What you see	What to do	Why
A machine is Failed	Read its failure reason, fix the host problem, boot it again. Delete and recreate if it will not recover	Rebuilding it failed partway
Machines skipped, disk missing	Restore the machine from a backup and boot, or delete the record and recreate	The disk file is gone, and no empty disk was put in its place
Everything running is now Powered off	Boot what you need, or turn VM autostart back on	VM autostart is off. The setting working, not a fault
Running but guest unreachable	Open its console and read the boot output	The guest did not come up on the network. Whether it is ever marked failed depends on the host being able to observe it (see below)
Unexpectedly Stopped	Boot it again	It was reaped at startup as an orphan of a previous failed start

When an unreachable guest is marked failed

Marking a guest failed takes evidence. If the host can observe it (the guest agent answers, or it has an address the host can probe), staying silent is evidence and the machine is eventually marked failed. If there is no way to observe it, silence proves nothing: the machine stays in Booting, and only restarts in quick succession, five within five minutes, mark it failed.

A missing disk is never replaced automatically

Recreating an empty disk would produce a machine that boots and looks healthy while all its data is gone. Virtainer Free would rather show you a failure.

What is not covered

Recovery only restores this host’s machines. Moving workloads to another host after a failure is clustering, which belongs to Virtainer Pro, not to Free.