Network Deployment (Distributed operating systems), v8.0 > Administer applications and their environment > Administer Transactions > Administer the transaction service


Configure transaction properties for peer recovery

Peer recovery for the transaction service enables servers in a cluster to complete outstanding work for a failed cluster member. Follow the steps in this topic to configure the transaction properties that are required for peer recovery of failed application servers in a cluster.

To enable transaction peer recovery between servers, have a common configuration of the resource providers between the participating server members. This means that peer recovery processing can only take place between members of the same server cluster. Although a cluster can contain servers that are at different versions of WAS, enable and configure high availability only if all servers in the cluster are at v6 or later.

Configure the transaction properties that are required for peer recovery is part of the overall task for configuring a cluster to use high availability support.


Procedure

  1. Configure the transaction log directory setting for each server in the cluster. We can configure the location of the transaction log directory by using either the administrative console or commands. The configuration is stored in the serverindex.xml node-level configuration file.

    Each server in the cluster must be able to access the log directories of other servers in the same cluster. For this reason, do not leave this setting unset. If you do not set a directory, the application server assumes a default location within the appropriate profile directory, which might not be accessible to other servers in the cluster.

    Each server in the cluster must also have a unique transaction log directory, to avoid attempts by multiple servers to access the same log file. For example, you could use the name of each server as part of the log directory name for that server.

    The storage mechanism used to host recovery log files (for example, you can use IBM Network attached storage (NAS) and shared SCSI drives, but not simple network share) and access to that mechanism (for example, through a local area network (LAN)), must support the file-based force operation used by the recovery log service to force data to disk.

    In addition, configure the mechanism by which the remote log files are accessed, to exploit any fault tolerance in the underlying file system. For example, by using the Network File System (NFS) and hard-mounting the remote directory containing the log files (by using the -o hard option of the NFS mount command), the NFS client will try again with a failed operation until the NFS server becomes available again.

    For more information about configuring transaction log directories, see Configure transaction properties for an application server.

    If we have migrated from a previous version of WAS, be aware that previous versions stored the recovery log configuration in the server.xml server-level configuration file. If you run existing scripting that configures the original recovery log settings, or migrate v5 application servers to a later version of WAS, the original transaction log directory configuration in the server.xml file is updated. The administrative console detects this condition and prompts you to save the configuration when you view the transaction service panel. This save operation saves the changed configuration to serverindex.xml, and resets the older fields to null. Change your existing scripting to target serverindex.xml at the earliest opportunity. New scripting should also target serverindex.xml.

  2. Enable the high availability function for the cluster, by completing the following steps on the cluster configuration panel of the WAS administrative console:

    1. In the administrative console...

      Servers > Clusters > WebSphere application server clusters > cluster_name .

    2. Select the Enable failover of transaction log recovery option.

    3. Click OK.

    For more information about enabling the high availability function for a cluster, see Server cluster settings.

  3. Decide which kind of transaction peer recovery to use by referring to How to choose between automated and manual transaction peer recovery.
  4. Complete one of the following actions, depending on the configuration that you require.


What to do next

We must also configure the compensation log location. Each server must have a unique compensation log directory and the compensation logs must be accessible, in a similar way to the transaction logs.


Related


Configure manual peer recovery for the transaction service
Transactional high availability
How to choose between automated and manual transaction peer recovery
Configure transaction properties for an application server
Configure automated peer recovery for the transaction service
Configure a server to use business activity support
Use the transaction service


Related


Server cluster settings
Compensation service settings

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