Backing up runtime data by using a SAN drive

The runtime data of your system is the information that is stored in transaction logs and compensation logs. You can use a storage area network (SAN) drive to copy files from your primary data center to a standby server.

About this task

Your runtime data is changing continually. Therefore, it is not reasonable to expect that the backup data center can always have the same state as the primary data center, unless you are using synchronous replication. In many environments, synchronous replication is not a valid option because there are performance impacts from a synchronous implementation.

The runtime data consists of the WebSphere® transaction logs and the compensation logs. Some of the files are associated with the IBM® Business Automation Workflow databases and some of the files are associated with any other resource managers. The files of interest are files that reflect the current state of the database tables, the current state of the transactions, and any other data that is managed by the resource that reflects the current state of the resource. These files vary from one implementation to another, depending on the database product or resource manager and vendor that is being used. The set of database tables in this runtime data includes at least all of the tables that are associated with your Business Automation Workflow configuration, such as persistent stores for messaging engines, business process applications, human tasks, and failed events.

Include the data that you require on a disk replication system with the following configuration:

Procedure

  1. Configure the original data center.
    1. Create directories that are needed for mounting the SAN, like /opt/ibm/WebSphere/tranlogs on the WebSphere servers and /opt/ibm/WebSphere/database on the database server.
    2. Mount the storage area network (SAN) drive.
    3. Configure the transaction service to use a distributed file system.
      The SAN creates two volumes, one for the database and one for the distributed file system, which is mounted on the SAN for its transaction logs. The distributed file system serves high availability by managing file locks for the distributed servers. The SAN serves disaster recovery by providing replication.
    4. Configure the database server to use this mount for its data and log files.
  2. Configure the disaster recovery data center.
    1. Create a directory in the disaster recovery data center similar to the one in the original data center.
    2. Load the disaster site recovery scripts or procedures for the run data replicated volume.
    3. Install and configure the data database catalog to find the appropriate files.
    The entire set of files for the runtime data must be included in the same snapshot and that snapshot must be taken at an instant of time. Your performance needs might require you to place the database log files on different disk arms than the database data or indicate some other placement needs. Work with your database vendor, your SAN vendor, and your operating system to configure the optimum configuration for your requirements. As you work with your SAN vendor, you must make sure that the write order is preserved in the snapshot and its replica.

What to do next

Set a schedule for the snapshot that is taken of the volume. The schedule determines whether you can meet your recovery point objective. For example, if you have a recovery point objective of 30 minutes, capture a snapshot at an interval of just less than 30 minutes. You must consider the time that it takes to actually take a snapshot and transfer it to the disaster data center. Your SAN provider can help you sort out those details.