SIRIS, ALTO, And NAS: Getting Started With NAS Guard



This article describes the NAS Guard feature available on Datto SIRIS, Datto ALTO, and Datto NAS.


  • Datto SIRIS
  • Datto ALTO
  • Datto NAS



The NAS Guard feature allows you to use your Datto appliance to capture backup snapshots of an SMB share from any system on your LAN, and then replicate those snapshots to the cloud.


NAS Guard does not natively support external share names which contain spaces. Datto recommends renaming these shares if possible. If you need to protect a share with spaces in its name, contact Datto Technical Support for assistance. 


Q: Is there a limitation to share size?
A: The current share size limit is 16 TB. If the NAS appliance or share you will be protecting is smaller than that or lacks the free space, the working share size will also be lower. The share on the Datto appliance cannot resize after you create it.

Q: If my share is on a domain, should I join the Datto appliance the domain?
A: Yes, you will need to join the Datto appliance to the domain as well. Doing so will allow the Datto appliance to connect to the external share using domain credentials.

Q: Are the share name and username I enter case-sensitive?
A: It is a best-practice to respect casing for the share name and username. Although some systems will disregard casing, others may not.

Q: Does NAS Guard preserve Unix permissions?
A: Depending on your environment, NAS Guard may or may not be able to preserve Unix permissions. Datto strongly recommends testing a restore to verify the preservation of user permissions.

Q: How would I add a group as read-only for a share?
A: Permissions within the share will reflect the permissions on the external share. There should be no need to re-create them on the Datto appliance.

Q: Which Datto appliances can use this feature?
A: Currently, any appliance running the latest version of Datto IRIS except for ALTO 1.

Q: Do I need to install anything on my hardware to back up my share?
A: You do not need to install any software. The Datto appliance will not make any modifications to the share during the pairing or backup processes. All external shares mount on the Datto appliance as read-only.

Q: What are my restore options?
A; You can mount file restores with or without NTFS permissions of snapshots from the Restore tab of the Datto appliance. You can also create file restores from the Recovery Launchpad.

Q: Is there a limit to the number of shares I can have on the Datto appliance?
A: There is currently no limit, although the collective size of the shares would determine how many you could add.

Q: Is there a way I can put a limit on share sizes?
A: Datto appliance determines the limit for the share's size during the initial pairing. Any restriction on the overall usage of the share would depend on how much change happens in the backups and the management of retention settings to limit global growth.

Q: Is there a way to exclude some folders on the external NAS share to prevent them from being backed up to the Datto device?
A: Yes. You can set explicit DENY permission on folders you don't want to be backed up for the user whose credentials you provide on the Configure Share Settings page.

Protecting a Share

To protect an externally-hosted share with NAS Guard, follow the steps described in SIRIS, ALTO, and NAS: Creating and Protecting Network Shares With a Datto Appliance.

Additional Resources

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