SIRIS, ALTO, and NAS: Basic troubleshooting for offsite synchronization issues



This article provides an overview of troubleshooting to perform when your offsite synchronization is behind schedule.


  • Datto SIRIS
  • Datto ALTO
  • Datto NAS


Review the alert email

The alert email will provide details about which Datto device is behind on offsite synchronization.

Log in to the Partner Portal 

You can verify the status of your offsite synchronization via the partner portal,
Review the Status page. Compare Latest Offsite Sync to Last Local Backup to determine which protected machines are behind.

figure1.pngFigure 1: Backup Status (click to enlarge)

Partner Portal: BCDR Status Page

Typically, when a single protected machine falls behind for several days, it is trying to send a large backup. If you recently added a new protected machine to the Datto device for backup, an initial full image will need to be replicated offsite. During this time offsite replication on other agents or systems tends to fall behind due to limited bandwidth.

Things to look for

  • How many protected machines are behind schedule?
  • Has the affected agent or system ever replicated offsite successfully?
  • Has anything replicated offsite recently?
  • Agents or systems that are behind 1-2 days are usually not malfunctioning and can just be monitored to ensure they catch up.

If this is a critical issue, a RoundTrip may be the best option to replicate offsite. However, if you do not address any underlying causes, synchronization could fall behind again. 

Log in to the Datto Device Web

On the Overview page, the Replication Status section will show you everything that is currently syncing offsite and estimated completion time.

fig1.pngFigure 2: Datto Device Web (click to enlarge)

If nothing appears to be replicating, You can navigate to Configure → Networking and check Connectivity Status on the Network Settings page.

fig2.pngFigure 3: Network Settings (click to enlarge)

If you see the connection to the offsite storage is marked as bad at the top of the page review the Networking Requirements

Investigate Large backups

Large backups take longer to transfer, getting smaller backups will help prevent offsite replication from falling behind. The articles below provide information on the causes and prevention of large backups.

Offsite Sync Settings

Review our Off-Site Synchronization Configuration Knowledge Base article.

In the Datto Device Web, navigate to Configure → Offsite Synchronization Check if the Off-Site Default Transmit Limit can be increased, The speed test will only provide you 50% of what is available. If you know what the sites’ upload bandwidth is, you can set this higher.

fig3.pngFigure 4: Default Transmit Limit and Speed Test (click to enlarge)

Off-Site Sync Scheduling

Setting your Off-Site Sync schedule to pause transfers will cause those transfers to restart when the schedule reverts to the default transfer speed. It can take a while for large transfers to resume where they left off. If you can throttle down to 1 MBps during this schedule, rather than pausing, it will help transfers complete faster.

fig4.pngFigure 5: Off-site Sync Schedule (click to enlarge)

Decreasing the number of concurrent offsite sync operations can increase the transfer speed when multiple transfers are involved.

  fig5.pngFigure 6: Concurrent Off-Site Sync (click to enlarge)


A roundtrip drive may be a good solution if you are more than ten days behind schedule or have multiple agents that have never replicated offsite.  Review our Roundtrip Overview article for details.

Open a ticket with Datto Technical Support

If you are unable to resolve the issue using the above steps, open a ticket with Datto Technical Support detailing what troubleshooting steps you have performed and the current status of the offsite synchronization.

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