Using SAN or NFS storage for Db2 supplemental logs for column-organized tables

You can use external SAN or NFS storage for the Db2® supplemental logs that are produced to support replication of column-organized tables.

About this task

When DATA CAPTURE CHANGES is enabled on a column-organized table, Db2 produces supplemental logs. The logs are read by the replication capture process and transmitted to the target system, where the apply process stages them in a directory that you specify. At both the source and target, the logs can be stored in /scratch (default) or SAN-attached storage. On the target, the files are deleted after each transaction is applied, so only enough disk space is needed to hold data that is modified by concurrently executing transactions.

If you expect workload volumes that might exceed the storage in this area, you might want to use external storage on the source or target systems for this purpose.

Procedure

  1. Follow these steps to add your external SAN or NFS file system into the IBM® Integrated Analytics System (IAS) cluster.
    Note: Do not run the apstart command to start the appliance at the end. You will do this in Step 3.
  2. On the IAS systems where you plan to use SAN or NFS storage for replication, run the apsetup command to change the appliance configuration to define which external SAN or NFS file system to use. Follow these steps:
    1. Enter 1 for General Appliance Settings.
    2. Enter 3 for Change Database Settings.
    3. Enter 4 for Set bluDR data path.
    4. Type the path to your external SAN or NFS file system within the container. For example, /external_mnt/NFS/backups.
    5. Type yes to confirm the path.
    6. As root, enter the following command inside the container: 
      [bluadmin@node0101-fab - Db2wh ~]$ cat /head/db2_config/bludr.cfg BLUDR_DB2_DATA_PATH=/external_mnt/NFS/backups/bluDR/
    The utility generates a configuration file, /head/db2_config/bludr.cfg, and makes other changes to enable the external file system for replication.
  3. Start the IAS appliance by using the apstart command.