An Image Based Upgrade (IBU) is the mechanism Datto uses to deliver new versions of the IRIS software stack to SIRIS, ALTO, and NAS appliances. Each IBU replaces the device's system image with a newer, fully tested build rather than patching individual components, so partners always run a known, complete version of the appliance software. Datto pushes IBUs to devices on a rolling basis according to the update channel and update window each device is assigned, giving partners predictable maintenance timing and the ability to control how quickly new features and fixes reach their fleet.
Update channels 
Every Datto device is assigned to an update channel, which determines how far behind the latest release the device's software stays. Channels are configured on the Global Device Settings page of the Remote Web, under Configure > Device Settings > Update Channel.
- Standard: Receives the latest IBU release as soon as it becomes available, including the newest features.
- Stable: Stays one or more releases behind Standard. This channel has had more time in production but may not yet include the newest features.
All IBU releases go through extended testing before Datto makes them available on any channel, regardless of which channel a device is on. Datto may also release an update outside of the normal schedule to address a security issue or other critical fix.
Update windows
The update window controls when a device is allowed to install an available IBU. Set this option on the same Global Device Settings page, under Update Window. Because the appliance reboots as part of the upgrade process, choose a window that falls during a period of low activity. The update window must be at least four hours long.
If a device misses its update window, for example because a backup or restore was in progress, the device's Overview page displays a banner stating that a software upgrade is available. Selecting the banner's Upgrade Now link starts the missed update immediately. An IBU does not install while restores are mounted or while a backup is in progress.
Release notes
Datto publishes release notes for every IBU in the Business Continuity & Disaster Recovery IRIS release notes article. Each entry lists the IRIS version number and its corresponding IBU number, along with the new features, improvements, and bug fixes included in that release. Update windows generally complete within one to two weeks of a release's publish date, since Datto rolls updates out to the fleet gradually rather than all at once.
How Image Based Upgrades work
Viewing the current image version 
To confirm which IBU a device is currently running, log in to the device's Remote Web and go to the Overview page (also called the Home tab). The Device Information section lists a Version (Device / SpeedSync) value. The Device version shown here is the device's current Datto OS (IRIS) version, which you can match against the version numbers listed in the release notes to identify the installed IBU.
Applying an update
When a new IBU is available for a device's channel, the device installs it automatically during the configured update window. If the window is missed, the device displays an upgrade banner on the Overview page that a user can select to start the update manually. During installation, the device reboots, so any active local restores or in-progress backups can delay or block the update until they finish.
If the device is out of date, you should check the update window to confirm it can update in the given window. Confirm there are no active restores that would prevent the device from updating. If the IBU version is similar to the latest version, it is possible that it has not been rolled out to that specific device and made available yet. If you need to update the device more quickly, then reach out to Datto Technical Support to assist with a manual upgrade.
