# Optimizing performance with Amazon FSx maintenance windows
<a name="maintenance-windows"></a>

As a fully-managed service, FSx for ONTAP regularly performs maintenance on and updates to your file system. This maintenance has no impact for most workloads. For workloads that are performance-sensitive, on rare occasions you may notice a brief (<60 seconds) impact on performance when maintenance is occurring; Amazon FSx enables you to use the maintenance window to control when any such potential maintenance activity occurs.

Patching occurs infrequently, typically once every several weeks. When patching occurs, each of your file system's file servers is patched one at a time, and each file server typically takes up to an hour to be patched. Before any file server is patched within an HA pair, your file system automatically fails over to the file servers' HA partner, which may result in a brief (less than 60 seconds) I/O pause for any I/O directed toward that HA pair. Your file system will then fail back, which may result in another brief (less than 60 seconds) I/O pause. You choose the maintenance window start time during file system creation. If you don't choose a window, one is automatically assigned.

**Important**  
To ensure that your file system can be patched successfully, FSx for ONTAP will bring online any offline volumes for the duration of the patching process. Any volumes that Amazon FSx brings back online will not be accessible to clients.

FSx for ONTAP allows you to adjust your maintenance window as needed to accommodate your workload and operational requirements. You can move your maintenance window as frequently as required, provided that a maintenance window occurs at least once every 14 days. If a patch is released and a maintenance window does not occur within 14 days, FSx for ONTAP will proceed with maintenance on the file system to ensure its security and reliability.

**Note**  
To ensure data integrity during maintenance activity, FSx for ONTAP closes all opportunistic locks and completes any pending write operations to the underlying storage volumes that are hosting your file system before maintenance begins.

You can use the Amazon FSx Management Console, AWS CLI, AWS API, or one of the AWS SDKs to change the maintenance window for your file systems.

**To change the weekly maintenance window (console)**

1. Open the Amazon FSx console at [https://console.aws.amazon.com/fsx/](https://console.aws.amazon.com/fsx/).

1. Choose **File systems** in the left hand navigation column.

1. Choose the file system that you want to change the weekly maintenance window for. The **Summary** file system details page appears.

1. Choose **Administration** to display the file system administration **Settings** panel.

1. Choose **Update** to display the **Change maintenance window** window.

1.  Enter the new day and time that you want the weekly maintenance window to start.

1. Choose **Save** to save your changes. The new maintenance start time is displayed in the file system administration **Settings** panel.

To change the weekly maintenance window using the [update-file-system](https://docs.aws.amazon.com/cli/latest/reference/fsx/update-file-system.html) CLI command, see [To update a file system (CLI)](updating-file-system.md#update-file-system-cli).