Oracle Solaris parameters Oracle Database Tips by Donald Burleson

This excellent Oracle/Solaris presentation by Sun shows suggestions for Sun Solaris kernel parameters for Oracle databases:

Get /etc/system right... not too hard

> "maxphys" at least 1M...

> "segmap_percent" set higher if using buffered
IO... more on that later :)

> IPC parameters.

>"shmmax" set to max.. S8, S9

>project.max-shm-memory resource control in S10

- Defaults to ¼ memory per project
- Modify via projadd or prctl

>Semaphore parameters... size according to # of users or "processes" init.ora parameter. Set higher than you initially need.

Also, see the details on using direct I/O for Oracle on Solaris.  The Sun articles notes that bypassing FS caching in favor of Oracle data buffers creates 2x faster throughput:

The article also notes the Solaris MPSS (Multiple Page Size Support) and recommended Solaris parameters:

Oracle9i and MPSS

> _use_realfree_heap=FALSE

> Changes pga allocation method from mmap to malloc

> ppgsz -o heap=4M -p `pgrep -u oracle '^ora'`

Oracle10g and MPSS

> _realfree_heap_pagesize_hint=4M

We also see this note on Oracle PGA sizing for Solaris 9 and Solaris 10:

Oracle supports large heap for PGA via a
hidden init.ora parameter:

● _use_realfree_heap_pagesize_hint=4194304

● Improved query performance by 14% on recent test.