HubStor Inc.

Overview of Link-based Stubbing

HubStor's link-based stubbing method is intended for use with CIFS/NFS-based storage, such as NetApp or EMC Celerra. It can also work with Windows-based file shares.

With HubStor's link-based stubbing, you can perform simple and effective policy-based storage tiering without the need of deploying an agent on the target storage appliance. To achieve this implementation, a central Windows machine needs to host the same 'Retrieval Service' that is used for HubStor's seamless stubbing method for Windows Server. The Retrieval Service acts as the controller for servicing recalls, and it has a file share directory configured which will contain information necessary to perform recalls from the cloud.

The actual stub in the link-based method is an .lnk file (shortcut) created by the HubStor Connector Service (HCS) according to your stubbing policies. The .lnk file seamlessly redirects requests from users or applications to the Retrieval Service which transparently recalls items and maintains a local cache for optimization of any subsequent retrieval requests.


HubStor’s link-based storage tiering for CIFS/NFS shares has these advantages:
  • No client software.
  • No storage vendor integration / server agent on the storage controller.
  • No network layer interception (high-risk integration).
  • Icons stay the same (but with shortcut overlay).
  • Stubs retrieve seamlessly for users AND applications.
  • Works with any storage vendor or protocol.
  • Streamlines hardware refreshes and storage migrations -- with HubStor's Export Utility, for any content that exists in HubStor, you have the complete flexibility to migrate, export, recover it to any location as original, seamless stubs, or link-based stubs. Thus, it becomes very easy to reduce storage demand while simplifying recovery and migrations.

Known Limitations

Link-based stubs have the following limitations and drawbacks:

  • Must 'Save As' to commit changes on retrieved items -- If a user recalls an item from a link-based stub and makes changes to the retrieved file, they will not be able to simply hit 'Save.' Instead, hitting 'Save' file force a 'Save As.'  Attempting to select the .lnk file will also fail since this attempts to overwrite the seamless stub pointed to by the shortcut file. If this user desires to overwrite the shortcut with the new version, the user must delete the shortcut and then save.
  • File icons change -- Shortcuts have the original file type icon but with a shortcut overlay.
  • File type change -- With link-based stubs, the actual file type changes to an .lnk file (Windows shortcut) which some applications may not like. For example, linked Excel files will break when one of the files is converted to a shortcut. For this reason, we recommend adjusting your policies to avoid converting file types that are problematic as shortcuts. As well, if you ever need to back out of any stubbing that you have applied, you can easily rehydrate the stubs using the Export Utility.
  • Other references to the original file -- Because the extension of the file changes to .lnk, any applications that attempt to open the file using the original name will fail. For example, in Office documents, the recent documents panel may reference a file that has been converted to a shortcut. Users clicking to open from recent documents will fail. This is likely rare since stubbing policies typically target data that has not been accessed in a long time (thus would never show in the recent items panel).
  • Authorization requires synced domain users -- Only domain users who are included in the Azure AD sync will be able to retrieve link-based files because HubStor performs a granular authorization check in the cloud before it satisfies any retrieval request.

Getting Started

Do you wish to configure link-based stubbing in your environment? See HOW TO INSTALL AND CONFIGURE LINK-BASED STUBBING.


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