SIRIS, ALTO, and NAS: Backing up iSCSI volumes on Datto devices



This article discusses the interaction between the ShadowSnap Agent, Datto Windows Agent, and Agentless systems with any locally connected iSCSI volumes.


  • ShadowSnap Agent
  • Datto Windows Agent
  • Datto Agentless Backups


iSCSI is used by the Datto solution to perform file restores where the restore must retain the original file's security permissions.  Shadowsnap uses iSCSI as the transfer method for encrypted backups.  Datto Windows Agent backups will fall back to iSCSI if the Mercury transport method fails.  The agent software will back up iSCSI attached volumes.  However, as these disks may not be present on boot, or if the parameters of the volume(s) are changed, frequent differential merges can occur. 

Agentless Systems and iSCSI

Agentless backups use the VMWare snapshot feature on the host to capture local changes. This feature does not support backing up iSCSI storage that is connected directly to the guest OS itself; these drives go undetected.

An iSCSI disk attached through the VM template in VMWare will back up. However, depending on how you set it up on the storage side, you may encounter the same issues as agent-based backups, discussed above.

Microsoft iSCSI Updates

  • Microsoft has two locations for iSCSI specific software packages. Ensure you are always using the latest software versions upon setup and configuration.
  • When setting up volumes for backup, make sure the volumes appear as locally accessible volumes on the target server and that, once configured, no changes to that configuration get made.
  • Configurations of these volumes are beyond the scope of Datto Technical Support.

Additional Resources

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