High availability for file servers

To have a truly highly available TrueSight Server Automation implementation, the file server must be highly available. The file server high-availability implementation must meet the following requirements:

  • Each Application Server at the primary site must have read and write access to the file server data.
  • Each Application Server at the primary site must have a consistent view of the data on the file server. Changes made to data in the file server must be immediately available to all Application Servers running at that site.

In addition, the idle connection timeout setting on the load balancer is important. If timeout values are set too low, the Application Server may observe connection closures and timeouts associated with losing and reopening connections to the file server.

Implementation

You can implement a highly available TrueSight Server Automation file server by using either of the following methods:

The method that you choose depends on the technologies available in your organization.

Network Attached Storage 

In a multi-node Application Server environment with an existing highly available network attached storage (NAS) solution already in place, the easier way to implement high availability on the file server is to add the file server to the NAS solution.  

Note

Microsoft Windows file servers cannot persistently mount a network share; therefore, the NAS solution is generally available only for file servers based on UNIX.

To implement a highly available file server by using a NAS solution across the application servers:

  • Each Application Server network mounts the network-available file system in read-write mode from the highly available NAS solution. The location of the network mount is the same across all Application Servers to ensure a uniform Application Server configuration.
  • A second "local" RSCD agent is installed on the application servers as described in How-to-configure-two-RSCD-agents-on-a-single-host.  The "local" RSCD is bound to localhost or some other IP on the system, the RSCD that is part of the Application Server install is bound to the IP address for the Application Server's hostname.
  • An alias is added in /etc/hosts for localhost - such as:
    • 127.0.0.1 localhost.localdomain localhost blfs
  • During Application Server software installation, provide the following information:
    • For the file server host name, use the alias that points to localhost (127.0.0.1).
    • For the file server path, specify the path to the NFS mount.
  • To avoid issues due to network connection resets, we recommend that you set the idle connection-related timeouts on the load balancer associated with the file server VIP to at least 60 minutes (1 hour).

In this setup each application server will point to to the "local" RSCD installed on itself for file server requests and there is no single point of failure - if there's a problem with one of the application servers the file server location is still available to the application servers.

Application clustering

A second option for implementing a highly available file server is to use an application clustering solution, such as Veritas Cluster Server. The details of implementing a cluster software installation are specific to the chosen software solution, but the basic requirements are as follows:

  • Install the high-availability cluster software on two server nodes.
  • Place a virtual IP address (VIP) specifically for the file server under the control of the cluster software. This VIP floats between the two cluster nodes according to the availability of the underlying server.
  • Configure the two servers with visibility to the same storage unit. For example, in a SAN environment, a storage logical unit (LUN) is presented to both servers.
    • The storage location could also be a NFS Filer for a Linux File Server.
  • Ensure that the file server file system resides on the storage unit that is shared by both servers. Access to the file server occurs as follows:
    • The file server VIP is associated with the file system. When the VIP is enabled on one of the server nodes, the file system is mounted on that server. This file system is mounted on only one of the nodes of the cluster at any one time.
    • The Application Servers access the file server through the RSCD agent. Because the RSCD is always active, service starts and stops are not required.
  • Specify the host name of the file server VIP and the location of the file system associated with that VIP on each Application Server.
  • To avoid issues due to network connection resets, we recommend that you set the idle connection-related timeouts on the load balancer associated with the file server VIP to at least 60 minutes (1 hour).

In this setup there is no special configuration required on the application servers (the "local" agent). 

 

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