HP-UX System Guidelines

• Use an HP-UX buffer cache that is at least as large as the default cache size (10% of physical memory). Use more than the default for large tables or indexed joins.

• Put swap space on a spindle different from DBEnvironment files and log files, especially for large multiuser operations. Increase the size of swap space if you are running more than 32 users.

• Use a file blocking factor of at least 4K. Serial scans may benefit from a blocking factor of 8K or larger.

• Use a larger interval for the sleep time for hpdbdaemon than the default of 30 seconds. The daemon is a process that wakes up every 30 seconds and connects to the DBEnvironment to determine whether there have been any abnormal terminations. If there have been abnormal terminations, the daemon cleans up by releasing locks and other system resources. If your system rarely experiences abnormal terminations, you can avoid the overhead of having daemons repeatedly connect to and release the DBEnvironment by increasing the sleep time. You should experiment with different intervals; a value of 60 seconds reduces the overhead by half. Remember, however, that increasing the sleep time also increases the time before cleanup takes place.

  You can set the daemon's sleep time with the C shell setenv command, as follows:

  setenv hpdbdmonsl n

  where the integer n is a number of seconds.

• Use the formula described under "Choosing the Number of Data Buffer Pages" to help determine the maximum number of data buffer pages to use on series 800 systems, where the maximum is limited by the size of swap space.

• You can use the HP-UX nice command to adjust the priority of executing processes. Refer to the manual page for nice.

Using HP-UX Raw Files for DBEFiles and Logs

Using raw files in HP-UX bypasses the operating system's normal buffering process. Considerable performance benefits can be derived from using raw files for logs and for DBEFiles when the primary data access method is random. However, there may be a performance penalty for sequential access to DBEFiles, since the file system's prefetching is bypassed.

In HP-UX, you can create raw DBEFiles and log files by specifying the pathname of a raw device in the CREATE DBEFILE statement or in the LOG DBEFILE clause of the START DBE NEW and START DBE NEWLOG statements.

For more information about raw files, refer to the appendix "Using HP-UX Raw Files for DBEFiles and Logs" in the ALLBASE/SQL Database Administration Guide.