HP-UX HB v13.00 Ch-22 - Performance and Tuning

HP-UX Handbook – Rev 13.00 Page 15 (of 19)
Chapter 22 Performance & Tuning
October 29, 2013
on. The write can have physically taken place or could be in the buffer cache but in
either case, acknowledgement has been sent. In the case of async, no waiting.
To implement asynchronous I/O on HP-UX for raw logical volumes:
* set the async_disk driver (Asynchronous Disk Pseudo Driver)to IN
in the HP-UX Kernel, this will require generating a new kernel and rebooting .
* create the device file:
# mknod /dev/async c 101 0x00000#
#=the minor number can be one of the following values:
0x000000 default-immediate reporting will not be used
a cache flush will be done before posting an IO operation complete
0x000001 enable immediate reporting
0x000002 flush the CPU cache after reads
0x000004 allow disks to timeout
0x000005 is a combination of 1 and 4
0x000007 is a combination of 1, 2 and 4
Note:
HP does not make minor number recommendations, have the client contact the database
vendor or product vendor to determine the correct minor number for your application.
Change the ownership to the appropriate group and owner :
# chown oracle:dba /dev/async
change the permissions:
# chmod 660 /dev/async
# vi /etc/privgroup
add 1 line : dba MLOCK
give the group MLOCK privileges : /usr/sbin/setprivgrp MLOCK
To verify if a group has the MLOCK privilege execute:
# /usr/bin/getprivgrp
The default number of available ports for asynchronous disks is 50 , this is tuned with the kernel
parameter max_async_ports, if greater than 50 disks are being used, this parameter needs to be
increased .
Check the system for the most current I/O and file system related patches.
Ideally patches should be no more than 1 year from current level.
Load Balancing
Load balancing policy depends on the environment, there are 4 choices :