3 Replies Latest reply on Jul 17, 2012 3:27 AM by JoeBidgood

    Lazy Caching

      I´m trying to understand better how the Lazy Caching works.

       

      1 - When a client doesn´t have VSE, if I create a client task to install it, when the client look for the VSE at the (newly created) SuperAgent repository (which is empty), the SuperAgent will start a connection to the ePO Master Repository to download the requested package and the it will serve the client who first requested it. Meanwhile the client will just wait for the package. Is that correct?

       

      2 - The maximum flushing time accepted by the Lazy Caching is 5 hours (300 minutes). After that time, the SuperAgent will erase all it´s repository. Is that correct?

       

      3 - If the above is correct, the Lazy Caching is not the best solution for the first time deployment, since the remote SuperAgent will donwload VSE + Full DAT for a first time installation and local systems will get the instalation packages from it. But after 5 hours, if new clients show up at the same location, the SuperAgent will have to re-download the VSE installation packages + Full DAT once again and that will keep happening each 5 hours until all local clients have VSE + 1 Full DAT installed and don´t request this packages anymore (only the incremental ones). Is that correct?

        • 1. Re: Lazy Caching
          JoeBidgood
          1 - When a client doesn´t have VSE, if I create a client task to install it, when the client look for the VSE at the (newly created) SuperAgent repository (which is empty), the SuperAgent will start a connection to the ePO Master Repository to download the requested package and the it will serve the client who first requested it. Meanwhile the client will just wait for the package. Is that correct?

           

          Yes.

           

          2 - The maximum flushing time accepted by the Lazy Caching is 5 hours (300 minutes). After that time, the SuperAgent will erase all it´s repository. Is that correct?

           

          No, not at all - that would be crazy   After the specified interval the SA flushes the cached details that it holds, not the actual files themselves. Imagine we have a flush period of 30 minutes - then  it would be something like this:

           

          1. At 12:00 a client asks the SA for the install set. The SA does not have a local copy so it gets it from the master, caches the file details in memory, and serves the file to the client.

          2. At 12:05 another client asks for it. The cache flush period has not expired, so the SA serves the file to the client.

          3. At 12:35 a third client asks for it. The cache flush period has expired, so the SA asks the master repository for its version to see if it has changed. In this scenario, nothing has changed on the master, so therefore the files that the SA has are still valid: the SA serves the file to the client and the cache flush timer is reset.

           

          Now imagine the same scenario, except that at 12:15 we check a new DAT file into the master repository.

          At 12:35 our third client asks for the VSE install set. The cache flush period has expired, so the SA asks the master repository for its version to see if it has changed. We've checked in a new DAT file, so the version of the master has now changed: the SA flushes the cache at this point. It then needs to find out if the particular file being requested has changed, so it obtains the file hash from the master, calculates the hash of the local copy and compares them. In this scenario the files are the same - we changed the DAT, not the VSE install set - so the SA serves the file to the client.

           

          The final scenario would be if we had checked in a new version of the VSE install package, in which case the file hashes would not match, and the SA would download the new version of the file and serve it to the client.

           

          HTH -

           

          Joe

          • 2. Re: Lazy Caching

            Thanks, Joe.

            I´ve lookd at the ePO Product Guide and the ePO and McAfee Agent online training at McAfee Partner website and I can say they don´t cover the Lazy Caching in a satisfatory manner.

             

            Thaks for all the info, Joe.

            That was really complete.

            • 3. Re: Lazy Caching
              JoeBidgood

              No problem   Lazy caching is a comparatively new feature and so it's not always that well understood...

               

              Regards -

               

              Joe