Methods for stopping an instance
There are four ways to perform a user-initiated stop: default stop, stop with skip OS shutdown, force stop, and force stop with skip OS shutdown. The following table compares the key differences between the stop methods:
| Stop method | Key purpose | Use case | CLI command |
|---|---|---|---|
| Default stop | Normal instance shutdown with attempted graceful OS shutdown. | Typical instance stop. |
|
| Stop with skip OS shutdown | Bypasses the graceful OS shutdown when stopping an instance. | When bypassing graceful OS shutdown is required. |
|
| Force stop | Handles stuck instances. Attempts a default stop first; if instance fails to stop, then forcibly stops the instance. | When instance is stuck in stopping state. |
|
| Force stop with skip OS shutdown | Force stops and bypasses the graceful OS shutdown when stopping an instance. | When force stop and bypassing graceful OS shutdown is required. |
|
For instructions on how to use each method, see the following:
The following sections provide more detailed information about the four different user-initiated stop methods.
Default stop
The default stop method is the standard way to stop an instance. When you issue
the StopInstances command, the instance transitions from the running
state, to stopping, and finally to stopped, as illustrated
by the following diagram:
Purpose: Normal instance shutdown with attempted graceful OS shutdown.
Data impact: Preserves data on the EBS root volume and data volumes. Loses data on the instance store volume.
When to use: First stop attempt for typical stops.
Note
If you've already attempted a stop with skip OS shutdown, a subsequent default stop attempt during the same state transition session will not perform a graceful OS shutdown. Bypassing the graceful OS shutdown is irreversible for the instance's current session.
Stop with skip OS shutdown
When bypassing the graceful OS shutdown is required, the stop with skip OS shutdown method can be used to stop an instance and bypass the graceful OS shutdown, as illustrated by the following diagram:
Warning
Bypassing the graceful OS shutdown might result in data loss or corruption (for example, memory contents not flushed to disk or loss of in-flight IOs) or skipped shutdown scripts.
Purpose: Bypass the graceful OS shutdown when stopping an instance.
Data impact: Might result in data loss or corruption. Contents of memory might not be flushed to disk and in-flight IOs might be lost. Might skip shutdown scripts.
When to use: When bypassing the graceful OS shutdown is required. If used while a default stop with graceful OS shutdown is in progress, the graceful OS shutdown will be bypassed.
Note
Bypassing the graceful OS shutdown is irreversible for the instance's current state transition session. A subsequent default stop attempt during this session will not attempt a graceful OS shutdown.
Force stop
The force stop method is used to handle instances that are stuck in the
stopping state. An instance typically becomes stuck due to an
underlying hardware issue (indicated by a failed system status check).
The force stop method first attempts a default stop. If the instance remains stuck in the
stopping state, the force parameter forcibly shuts
down the instance and transitions the instance to the stopped state, as
indicated by the following diagram:
Purpose: Handles instances stuck in the
stopping state. Attempts a default stop first. If the instance
fails to stop, then forcibly shuts down the instance.
Data impact: Attempts a default stop first, but if force stop goes ahead, then might cause data loss or corruption. In rare cases, results in post-stop writes to EBS volumes or other shared resources.
When to use: Second stop attempt when an instance remains stuck after a default stop. For more information, see Troubleshoot Amazon EC2 instance stop issues.
Force stop with skip OS shutdown
When force stopping and bypassing the graceful OS shutdown is required, the force
stop with skip OS shutdown method can be used to bring an instance to the
stopped state, as illustrated in the following diagram:
Purpose: Combines force stop with bypassing a graceful OS shutdown when stopping an instance.
Data impact: Skip OS shutdown might result in data loss or corruption. Contents of memory might not be flushed to disk and in-flight IOs might be lost. Might skip shutdown scripts. If force stop goes ahead, then might cause additional data loss or corruption. In rare cases, results in post-stop writes to the EBS volumes or other shared resources.
When to use: When you want to be sure that your instance will stop and you want to bypass the graceful OS shutdown. If used while a default stop with graceful OS shutdown is in progress, the graceful OS shutdown will be bypassed.
