Performance and failover considerations

If you use a large number of persistent messages or large messages in your applications, there is an associated overhead of journaling these messages.

This increases your system disk input/output. If this disk input/output becomes excessive, performance suffers.

Ensure that you have sufficient disk activation to cope with this possibility, or consider a separate ASP in which to hold your queue manager journal receivers.

We can specify which ASP your queue manager library and journals are stored on when you create your queue manager using the ASP parameter of CRTMQM. By default, the queue manager library and journals and IFS data are stored in the same ASP: the system ASP.

ASPs allow isolation of objects on one or more specific disk units. This can also reduce the loss of data because of a disk media failure. In most cases, only the data that is stored on disk units in the affected ASP is lost.

You are recommended to store the queue manager library and journal data in separate user ASPs to that of the root IFS file system to provide failover and reduce disk contention.

For more information, see OS/400 V4R4M0 Backup and Recovery