Stop using DuplicateDir tag for failover support architecutre in FMS!

I was working on fail-over architecture for our application and came across this <duplicateDir> tag in application.xml which, I am quite sure that many of you advanced FMS users already know or some of you might be already using it in your FMS based applications to support Fail-over.

I designed an architecture for our application in this architecture I was trying to keep the same folder hierarchy on both server.  So that if FMS (machine 1) stops working and users connects to same running instance from FMS (machine 2) they get the last updated data on FMS (machine 2) dumped through duplicate functionality from FMS1. There is a property in tag to attach application directory name to the path on other server or not i.e. by assigning value true you can add application directory name to the path or it will just copy the files at instance path. But when I was switching off the app directory name by assigning false it was just copying all sharedobject/streams at the root instead of at instance path. If I keep the app directory by assigning it  true.  It copies at correct path including instance path but attaching application directory path at beginning.

Anyway thinking that it’s some kind of bug or I might be doing something wrong. I posted a query regarding it on Flashcomguru mailing list and here comes the reply from FMS team member:

The <DuplicateDir> functionality for SharedObjects has been deprecated; it probably shouldn’t have been documented, my apologies. I’ve added a note to the online docs (comments appear at the bottom of the page):

So what do we do now? I mean how do we achieve the duplicate directory functionality for fail-over in case we have planned for future? Or in case some of you were using it in past? So here is the reply from Adobe engineering team:

<DuplicateDir> won’t be supported moving forward and existing bugs won’t be fixed, so it’s not a good idea to use it.
You can use the File plug-in to build a fail-over architecture for streams.

So good luck for all the FMS developers who were or are in process of implementing failover architecture and were planning to or already using this duplicate directory in their architecture.

Some other good way to implement failover is to follow architecture suggested by Rober A. Colvin

I am just curious to know that will NAS/SAN introduce any kind of latency?  Compared to the files being stored on and delivered from same  machine?

Please let me know if anyone has any idea about it.


3 thoughts on “Stop using DuplicateDir tag for failover support architecutre in FMS!

  1. it depends on your setup from an FMS …etc
    -number of files being saved to the NAS( you will see an increase in CPU and sockets used).
    -if your machines are running cool (under 50%) your clients shouldn’t notice the difference(*FMS is really copying whats in memory).

    Obviously you have no need for additional Sockets and FMS doesn’t have to work as hard to write locally ,CPU will be less.

    • Thanks for the reply Robert.
      I will check this out in near future as it seems NAS is the way to go for now rather then writing a file plug-in for copying files.

  2. We are using NAS which is storage that has more than 500TB which is shared with other services there is no issue. As Robert already said under 50% CPU no issues. We ran load tests as well 1Gige card runs out before you reach 50% CPU.

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