Saturday, August 26, 2017

EBS 12.2- An important point to be considered when building a Shared Application Filesystem using NFS

Nowadays, I come across Multi-AppsNode EBS installations, which are based on Shared Application Filesystem technology. I see mostly NFS is utilized rather OCFS or any other shared filesystem and that's why I wanted to write a few words about it.

First, shared Appl_top using NFS is completely supported and documented.  The Oracle EBS system supports shared Application Filesystem terminology starting from application version 11i, and it’s supported until 12.2. It is easy to build and use.
Ofcourse, there are some points to be considered :

  • The sharing of APPL_TOP in a Windows environment is not supported.
  • INST_TOP also will be in shared locations unlike earlier releases.
  • All application tiers sharing the file system should be running on the same operating system.
  • Shared application tier file systems should be in read-write mode on all application tiers.

In addition to the points above; the most point of all is I think, the high availability.

I mean, when we build a shared Application Filesystem using NFS, we actually become dependent on NFS shares. (NFS shared + primary node OS + primary node Hardware = primary node's availability)
That is, we export NFS shares from the primary apps node to the secondary apps node.
So, if the primary apps node is down (as a result of a system failure) , our EBS application services on both nodes go down.
We can't start them on the surviving nodes, unless we do a quick failover operation in the Storage level.
That is , in case of a failure that can happen in the primary apps node, the storage admin should map the disks to the secondary node and in that secondary node, the disks should be mounted.
By doing so, the secondary node can read-write the Apps filesystem directly (without a need to mount the NFS shares exported by the primary node -- primary is down..).
Ofcourse, a revert-back operation should be planned to be done in the Storage and OS levels in order to revert back changes when the primary will be up.

So, for load balancing, it is okay, but for high availability, this configuration named "Shared Application Filesystem using NFS" is a little inadequate. I mean, there are things to be done and there is downtime for this.

Well... If you need  both the "High availability" and "Load Balancing" on EBS Apps Tier, my recommendation is, "using a non-shared Application Filesystem, where the apps nodes may have their own dedicated application file systems." (you can also consider OCFS and shared Application filesystem)

You can implement the non-shared Application Filesystem based multi Node configuration by doing a single apps tier installation and then adding a node.

Here is a document to followed ->
"Cloning Oracle Applications Release 12 with Rapid Clone (Doc ID 406982.1) "Option 3: Adding a New Node to an Existing System"

Don't bother the name of the document above.. It includes Cloning, yes.. But, what we do for building a non-shared filesystem based multi node EBS apps tier is the same as the things documented in that node. Specifically, the section named Option 3: Adding a New Node to an Existing System".

2 comments :

  1. Hello Erman,

    Thank you for sharing your knowledge on this.. I have one question.. is it possible to setup PCP with local filesystem? I check all the note and oracle document which says PCP need shared file system.

    2. We want to setup share filesystem for PCP and we don't have option to use the NFS, we cannot use ACFS as concurrent nodes are running on Oracle solaris.

    Please advise if any option for this.

    Thank You

    Regards,
    Jignesh

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  2. 1)Wich documents are they? Did you read this note -> Configuring and Managing Oracle E-Business Suite Release 12.2.x Forms and Concurrent Processing for Oracle RAC (Doc ID 2029173.1)" -> THis document is written for an environment with four RAC Database nodes and "four non-shared" application tiers. and it describes PCP.

    I don't think shared filesystem is a "must" for PCP. But it is recommended. Viewing Log and out files may be the main cause for that. You can however; find a workaround for that too.

    2) Read https://blogs.oracle.com/stevenchan/choosing-a-shared-file-system-for-oracle-e-business-suite. I think you can use any shared filesystem as long as it is transparent to EBS applications. Read that article and see.

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