HubStor Inc.

Overview of Stubbing Options

Stubbing is the practice of moving the original data from the source and replacing it with a smaller shortcut or placeholder which acts as a pointer to assist with recalling the original item.

Stubbing is controlled with policies within each connector that is setup in the HubStor Connector Service. It is common that older and larger items will be stubbed. For example, a stubbing policy might specify that video and audio file types that have not been accessed in over 12 months are in scope of stubbing.

HubStor provides three stubbing methods:
  1. Seamless stubs (aka. invisible stubbing/ghosting) -- Seamless stubbing is best suited to Windows Server environments and provides a transparent experience to users and applications. Items that are stubbed become offline files where their size on disk is near zero. The seamless stubs have the same metadata and file type icon as the original, and they automatically retrieve on any file open command whether that be coming from a user or application. When items retrieve, there is an optional local caching feature that optimizes subsequent recalls (i.e. the retrieval agent always checks the local cache instead and only fetches from the cloud if necessary). Seamless stubbing requires the 'Retrieval Service', a Windows Server agent, to be installed on each instance of Windows Server that may handle requests on seamless stubs. Thus seamless stubbing is available only to storage that is front-ended with Windows Server file servers and SharePoint Documents(Lists not supported). See OVERVIEW OF SEAMLESS STUBBING AND THE RETRIEVAL SERVICE.
  1. Link-based stubs (aka. seamless stubbing for CIFS/NFS) -- Link-based stubs work with any storage (Windows, CIFS, NFS) to provide a near-seamless stubbing method for CIFS and NFS-based storage. CIFS-based storage, such as NetApp or EMC Celerra, is highly scalable but presents a lock-in challenge to customers. Traditional file-level storage tiering methods for these storage appliances has involved either complex network-layer intercepts, client software, or vendor specific agent integrations. With HubStor's link-based stubbing, you can perform simple and effective policy-based storage tiering without the headaches of older methods. To achieve this implementation, a central Windows machine needs to host the same 'Retrieval Service' that is used for seamless stubs. This service will act as the controller for servicing recalls. A stub share directory must be created which will contain information necessary to recall from the cloud. Next, you create stubbing policies in connectors within the HubStor Connector Service as you normally would. In the CIFS/NFS directory, stubbed items appears as shortcuts. When a user or application opens the file, the request is handled by the central Retrieval Service. See OVERVIEW OF LINK-BASED STUBBING.
  1. HTML stubs (aka. universal stubs) -- HTML stubs provide an agentless approach to stubbing that can work with any storage (Windows, CIFS, NFS). However, HTML stubs are not transparent to users and they do not automatically retrieve for applications or processes. The HTML stub is an HTML file that replaces the original item. When a user clicks the HTML stub, the HTML content displays in the user's default browser with a message saying the item has been archived and offering links to download it or view it in the HubStor User Portal. See HOW HTML-BASED FILE SYSTEM STUBS WORK.

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