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BrachCache: Data in hosted cache server is read-only? RRS feed

  • Question

  • Hi

    If I setup hosted cache server in BranchCache Hosted Cache mode, and let's assume file content has been upload to the hosted cache server. 

    So next time when client computer ask for same file, suppose it will get content from hosted cache server directly. The Question is,

    1. If user modify the content, the modified data will be cached to host cache server then replicate to content server? Or hosted cache server is read-only, each update-> update file server content?

    2.  Can BranchCache support file locking? Since users can modify data on Hosted cache server or Content Server. If user A in Branch opens file which located in Hosted cache server, before it save the file,  user B in HQ opens same file which located in Content Server. Later on user A and B save file one after another. If so, there is conflict. DFSR uses a “last writer wins” conflict algorithm,  how about BrachCache in the same situation?

    Thanks.







    Computer Role

    Computer Name

    IP Address

    Content server  in HQ

    Content-01

    192.168.0.100

    Hosted cache server in Branch

    Hosted-01

    10.1.0.100

    Client computer (User A) in Branch

    Client-01

    10.1.1.2

    Client computer (User B) in HQ

    Client-02

    192.168.1.2


    • Edited by goodhehe Wednesday, November 2, 2011 9:44 AM
    Wednesday, November 2, 2011 9:41 AM

Answers

  • goodhehe:

    (1)  Client retrieves content from the Hosted Cache Server.  If the Client modifies the content and saves it to the HQ Content Server, the data on the Hosted Cache Sever no longer fully matches as the content has been changed.  When the updated file is downloaded by this Client or another Client, new data will be offered to the Hosted Cache Server and that's when the data gets updated on the Hosted Cache Sever.  Note that if the above save operation introduces no changes, then the data on the Hosted Cache Server should still match.

    (2)  File locking does not come into play when using BranchCache.  BranchCache operates on the download/read path.  Users are not directly modifying any data on the Hosted Cache Server.  Note: there's no concept of files on the Hosted Cache Server - only pieces of data are cached there.

    When a Client modifies a file, it's on the local machine or on the Content Server - and not on the Hosted Cache Server.  If there's data cached on the Hosted Cache Server that make up a part of or a complete file on the Content Server, the client will attempt to retrieve those pieces from the Hosted Cache Server and then request any remaining pieces from the Content Server as missing data.

    Let me know if I've answered your questions and thanks for using BranchCache. 

    Tuesday, November 8, 2011 2:18 AM
  • Here's a great reference that helps to answer your questions:

    Windows Server 2008 R2 BranchCache Datasheet http://download.microsoft.com/download/3/E/6/3E6143AA-7961-4230-B657-D23933E4FD2A/BranchCache%20Datasheet.pdf

    found on this page:

    http://www.microsoft.com/en-us/server-cloud/windows-server/branchcache.aspx

    Thanks.

    Tuesday, November 8, 2011 2:24 AM

All replies

  • goodhehe:

    (1)  Client retrieves content from the Hosted Cache Server.  If the Client modifies the content and saves it to the HQ Content Server, the data on the Hosted Cache Sever no longer fully matches as the content has been changed.  When the updated file is downloaded by this Client or another Client, new data will be offered to the Hosted Cache Server and that's when the data gets updated on the Hosted Cache Sever.  Note that if the above save operation introduces no changes, then the data on the Hosted Cache Server should still match.

    (2)  File locking does not come into play when using BranchCache.  BranchCache operates on the download/read path.  Users are not directly modifying any data on the Hosted Cache Server.  Note: there's no concept of files on the Hosted Cache Server - only pieces of data are cached there.

    When a Client modifies a file, it's on the local machine or on the Content Server - and not on the Hosted Cache Server.  If there's data cached on the Hosted Cache Server that make up a part of or a complete file on the Content Server, the client will attempt to retrieve those pieces from the Hosted Cache Server and then request any remaining pieces from the Content Server as missing data.

    Let me know if I've answered your questions and thanks for using BranchCache. 

    Tuesday, November 8, 2011 2:18 AM
  • Here's a great reference that helps to answer your questions:

    Windows Server 2008 R2 BranchCache Datasheet http://download.microsoft.com/download/3/E/6/3E6143AA-7961-4230-B657-D23933E4FD2A/BranchCache%20Datasheet.pdf

    found on this page:

    http://www.microsoft.com/en-us/server-cloud/windows-server/branchcache.aspx

    Thanks.

    Tuesday, November 8, 2011 2:24 AM