Recovery log configuration and tuning

The management of the recovery log is important to normal operations for the server.

• For the active log and active log mirror, follow these practices:
  • Ensure that the directory that holds the active log is as large as, or larger than, the size of the active log. A directory that is larger than the active log can accommodate failovers if they occur.

    Creating an active log mirror provides higher reliability, but comes at a cost. When the log is mirrored, it can affect performance because of the doubled I/O activity that is required to maintain the mirror. The additional space that the log mirror requires is another factor to consider. If you are using separate physical disks for the active log, use the MIRRORLOGDIR parameter in the DSMSERV FORMAT command to find the mirror log directory. After installing the server, change the mirror log directory location by changing the value of the MIRRORLOGDIR option in the server options file and restarting the server.

  • Use disk system read-ahead processing to archive active logs more quickly.
  • If there are active log performance issues, you can set the LOGBUFSZ server option in the dsmserv.opt file to 256 and restart the server.
• For the archive log and failover archive log, follow these practices:
  • You can optionally create an archive failover log to store archive log files when the archive log directory is full. It is a best practice to maintain an archive failover log.
  • Do not share archive log space with other applications, including other Tivoli® Storage Manager servers. Other applications can write to the archive log directory and use the space that is required by the archive log. Ensure that each server has a separate storage location that is owned and managed by that specific server.
  • Set aside space in the failover archive log for possible emergency use.