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Instance Actions

This page describes the different actions you can perform on instances in Safespring Compute, such as stopping, starting, rebooting, and shelving.

This page includes OpenStack CLI commands. See the API Access documentation for instructions on how to install and configure the command line client.

Billing implications

At Safespring, you are billed for an instance for as long as it exists — even if it is shut off, paused, suspended, or shelved. Billing is based on the instance existing on a compute node, not on whether it is running. The only way to stop being billed for an instance is to delete it.

Overview

The following actions are available for instances:

Action	Description	Billed for compute	Resources freed
Shut off	Shuts down the instance gracefully. The instance remains allocated on a compute node.	Yes	None
Start	Boots a previously shut off instance.	Yes	N/A
Reboot	Restarts the instance. Can be soft (graceful) or hard (forced).	Yes	None
Pause	Freezes the instance in memory. Very fast to resume.	Yes	None
Unpause	Resumes a paused instance from memory.	Yes	N/A
Suspend	Saves instance state to disk, similar to hibernation.	Yes	CPU and RAM freed
Resume	Restores a suspended instance from disk.	Yes	N/A
Shelve	Shuts down the instance and removes it from the compute node. A snapshot is stored.	Yes	CPU, RAM, and compute node
Unshelve	Restores a shelved instance from its snapshot onto a compute node.	Yes	N/A

Shut off and start

Shutting off an instance performs a graceful shutdown of the operating system, similar to pressing the power button on a physical server. The instance stays allocated on its compute node and all resources (disk, network, IP address) are preserved.

Using the Horizon dashboard

In the instance list, select Shut Off Instance from the dropdown menu. To start it again, select Start Instance.

Using the CLI

openstack server stop my-instance

openstack server start my-instance

Note

A shut off instance still occupies resources on the compute node and you will continue to be billed for it. Shutting off, pausing, suspending, and shelving do not reduce billing. The only way to stop being billed for an instance is to delete it.

Reboot

Rebooting restarts the instance operating system. A soft reboot sends a shutdown signal to the OS and then boots it again. A hard reboot is the equivalent of a power cycle and should be used when the instance is unresponsive.

Using the Horizon dashboard

Select Soft Reboot Instance or Hard Reboot Instance from the dropdown menu in the instance list.

Using the CLI

Soft reboot (graceful):

openstack server reboot my-instance

Hard reboot (forced):

openstack server reboot --hard my-instance

Warning

A hard reboot does not give the operating system a chance to shut down gracefully. Use it only when the instance is not responding to a soft reboot.

Pause and unpause

Pausing an instance freezes it in its current state in memory. The instance stops executing but its memory contents are preserved on the compute node. Unpausing restores execution immediately, making this the fastest way to temporarily stop and resume an instance.

Using the Horizon dashboard

Select Pause Instance from the dropdown menu. To resume, select Resume Instance.

Using the CLI

openstack server pause my-instance

openstack server unpause my-instance

Suspend and resume

Suspending an instance saves its entire state (including memory) to disk, similar to hibernating a laptop. This frees up CPU and RAM on the compute node while allowing you to restore the instance to exactly the state it was in when suspended.

Using the Horizon dashboard

Select Suspend Instance from the dropdown menu. To restore, select Resume Instance.

Using the CLI

openstack server suspend my-instance

openstack server resume my-instance

Shelve and unshelve

Shelving an instance shuts it down, takes a snapshot of it, and removes it from the compute node. The instance can be restored later from its snapshot using unshelve, though this takes longer than starting a shut off instance since it must be scheduled onto a compute node again.

Warning

Shelving does not reduce your billing. You are billed for an instance for as long as it exists, regardless of whether it is running, shut off, or shelved. The only way to stop being billed for an instance is to delete it.

Using the Horizon dashboard

Select Shelve Instance from the dropdown menu. To restore, select Unshelve Instance.

Using the CLI

openstack server shelve my-instance

openstack server unshelve my-instance

Rescue mode

If your instance has a broken root filesystem and cannot boot properly, you can use rescue mode to boot from a different image and repair the disk. This is covered in the Troubleshooting documentation.