SteelHead™ Deployment Guide : Proxy File Services Deployments : Overview of Proxy File Services
  
Overview of Proxy File Services
This section describes Proxy File Services (PFS) and how it works. This section includes the following topics:
  • When to Use PFS
  • PFS Terms
    • PFS is an integrated virtual file server that allows you to store copies of files on the SteelHead with Windows file access, creating several options for transmitting data between remote offices and centralized locations with improved performance. Data is configured into file shares that are periodically synchronized transparently in the background, over the optimized connection of the SteelHead. PFS leverages the integrated disk capacity of the SteelHead to store file-based data in a format that allows it to be retrieved by NAS clients.
    When to Use PFS
    Before you configure PFS, evaluate whether it is suitable for your network needs. The advantages of using PFS are:
  • LAN access to data residing across the WAN - File access performance is improved between central and remote locations. PFS creates an integrated file server, enabling clients to access data directly from the proxy filer on the LAN instead of the WAN. Transparently in the background, data on the proxy filer is synchronized with data from the origin file server over the WAN.
  • Continuous access to files in the event of WAN disruption - PFS provides support for disconnected operations. In the event of a network disruption that prevents access over the WAN to the origin server, files can still be accessed on the local SteelHead.
  • Simple branch infrastructure and backup architectures - PFS consolidates file servers and local tape backup from the branch into the data center. PFS enables a reduction in number and size of backup windows running in complex backup architectures.
  • Automatic content distribution - PFS provides a means for automatically distributing new and changed content throughout a network.
    • If any of these advantages can benefit your environment, then enabling PFS in the SteelHead is appropriate.
    However, PFS requires preidentification of files and is not appropriate in environments in which there is concurrent read-write access to data from multiple sites:
  • Preidentification of PFS files - PFS requires that files accessed over the WAN are identified in advance. If the data set accessed by the remote users is larger than the specified capacity of your SteelHead model or if it cannot be identified in advance, end-users must access the origin server directly through the SteelHead without PFS. (This configuration is also referred to as Global mode.)
  • Concurrent read-write data access from multiple sites - In a network environment where users from multiple branch offices update a common set of centralized files and records over the WAN, the SteelHead without PFS is the most appropriate solution because file locking is directed between the client and the server. The SteelHead always consults the origin server in response to a client request; it never provides a proxy response or data from its RiOS data store without consulting the origin server.
    • PFS Terms
    The following terms are used to describe PFS processes and devices.
     
    PFS Term
    Description
    Proxy file server
    A virtual file server that resides on the SteelHead and provides Windows file access (with ACLs) capability at a branch office on the LAN. The proxy file server is populated over an optimized WAN connection with data from the origin server.
    Origin file server
    A server located in the data center that hosts the origin data volumes.
    Domain mode
    A PFS configuration in which the SteelHead joins a Windows domain (typically your company domain) as a member.
    Domain controller (DC)
    The host that provides user login service in the domain. (Typically, with Windows 2000 Active Directory Service domains, given a domain name, the system automatically retrieves the DC name.)
    Local workgroup mode
    A PFS configuration in which you define a workgroup and add individual users who have access to the PFS shares on the SteelHead.
    Share
    The data volume exported from the origin server to the remote SteelHead.
    Important: The PFS share and the origin-server share name cannot contain Unicode characters. The Management Console does not support Unicode characters.
    Local name
    The name that you assign to a share on the SteelHead. This is the name by which users identify and map a share.
    Important: The PFS share and the origin-server share name cannot contain Unicode characters. The Management Console does not support Unicode characters.
    Remote path
    The path to the data on the origin server or the UNC path of a share you want to make available to PFS.
    Share synchronization
    The process by which data on the proxy file server is synchronized with the origin server. Synchronization runs periodically in the background, based on your configuration. You can configure the SteelHead to refresh the data automatically at an interval you specify or manually at any time.
    The levels of synchronization are as follows:
  • Incremental Synchronization - In incremental synchronization, only new and changed data is sent between the proxy file server and the origin file server.
  • Full Synchronization - In full synchronization, a full directory comparison is performed. The last full synchronization is sent between the proxy file server and the origin file server.
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