Manage Multi-Session Fleet Instances
When running multi-session fleets on Amazon WorkSpaces Applications, multiple user sessions share a fleet instance. Unlike single-session fleets — where each instance serves one user and is automatically recycled after the session is terminated — multi-session instances can remain active for extended periods as long as users continue to occupy sessions on them.
This creates an important operational consideration: a multi-session instance cannot be terminated while active user sessions are running. If an instance is never fully vacated, it may never be reclaimed or rebooted, which means:
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Image updates may not propagate — new image versions containing patches, software updates, or security fixes will not reach an instance until all sessions on it have ended and the instance is recycled.
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Fleet hygiene is harder to maintain — without a mechanism to gracefully cycle instances, administrators must manually restart fleets or terminate all active sessions to apply updates, which can be disruptive to end users.
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Long-running instances may experience performance degradation — instances that remain active for extended periods without a restart can accumulate resource contention, memory pressure, and other system-level issues over time, leading to a degraded experience for end users sharing that instance.
To address this, WorkSpaces Applications provides a method to manage the lifecycle of individual fleet instances through a process called draining (also referred to as Drain Mode).
Putting an instance in Drain Mode impacts the capacity of the fleet. The fleet capacity metrics are available at Viewing Fleet Usage Using the Console.
