Oracle & Asynchronous IO

[Fred Ruffet]

Hi,

I'm having troubles configuring Async IOs on a 11.00 server here.

Config is :
HP-UX 11.00 64 bits
Oracle 9i (9.2.0.4)
*no* Online JFS

I've done the following steps :
. Setting up /etc/privgroup
#cat /etc/privgroup
dba MLOCK
dba RTSCHED RTPRIO
. used setprivgroup -f /etc/privgroup
. add lines in spfile
disk_async_io=true
hpux_sched_noage=178
. restart Oracle DB

After that, each session on DB creates a file in udump dir with a line like that :
Ioctl ASYNC_CONFIG error, errno = 1

Note that the server is really short on RAM compared to DB size (but I don't believe it matters).

One strange thing I noticed is that when I do getprivgrp, I get the foillowing :
global privileges: CHOWN
dba: RTPRIO RTSCHED
I don't see "dba: MLOCK". Is it normal ?

I'm not complaining about DB perfs, but udump is filling with those little trace files, and I'm looking for a way to fix.

Thanks for any help,

Fred

[Zygmunt Krawczyk]

Hi Fred,

read the doc:
"Best practices for Oracle on HP-UX"
http://h21007.www2.hp.com/dspp/files/unprotected/database/HP3KOracle.ppt

Regards,
Zygmunt

[Steven E. Protter · Accepted solution]

Hi Fred,

We don't have this:
dba RTSCHED RTPRIO

and we're not getting the little dump files.

Maybe you want to back out that change and see if it helps.

We are successfully using asynchronous i/o.

SEP

[Sanjay_6]

Hi Fred,

Have you enabled the aync drivers in the kernel. Also the /dev/async file should be owned by oracle:dba

These are the steps involved.

1. cd /stand/build

2. /usr/lbin/sysadm/system_prep -s system

3. vi /stand/build/system - add the following 2 lines: asyncdsk & asyncdsk_included

4. mk_kernel -s /stand/build/system

5. cp /stand/system /stand/system.prev

6. cp /stand/build/system /stand

7. kmupdate /stand/build/vmunix_test

8. cd /

9. shutdown -r -y now

10. after the system is reboot..

Use sam to change the value of the parameter max_async_port from 50 -> 1024

11. check that the driver is installed: lsdev | grep 101

12. mknod /dev/async c 101 0x000000

13. chown oracle:dba /dev/async

14. chmod 660 /dev/async

15. vi /etc/privgroup - add 1 line:
dba MLOCK

16. run the command: setprivgrp -f /etc/privgroup

17. run the command: getprivgrp, and make sure that you can the following
output:

global prvileges: CHOWN
dba: MLOCK

18. make sure that the oracle team add the following parameter to the oracle
init files:

disk_asynch_io=true

Hope this helps.

Regds

[RAC_1]

Also check the perms on /dev/async
They should be oracle:dba and read for both

Anil

[Fred Ruffet]

Zygmunt,

It's exactly the doc I used to set up async IO :)

SEP,

This line is for process scheduling. It is mentionned in doc zygmunt said. I will try without it.

Sanjay and RAC,

If I give /dev/async to oracle:dba, no other user will be able to use it... I don't have another user who needs, but I find it a little strange.

/dev/async belongs to bin:bin and is rw for everybody.
# ll /dev/async*
crw-rw-rw- 1 bin bin 101 0x000000 Feb 15 2001 /dev/async
crw-rw-rw- 1 bin bin 101 0x000000 Feb 24 2004 /dev/asyncdsk

asyncdsk is already in kernel.
# kmadmin -k | grep async
asyncdsk_included
asyncdsk

Regards,

Fred

[Fred Ruffet]

SEP had pointed right :)

In my /etc/privgroup, dba group has its rights on two lines. When I issue a getprivgrp, I only see second line. Putting all on one line seems to solve it...

One more question : Is /etc/privgroup read at each boot, or do I need to include a setprivgrp in startup scripts ?

Regards,

Fred

[Fred Ruffet]

no need to answer my last question :
# grep /etc/privgroup /sbin/init.d/*
/sbin/init.d/set_prvgrp: if [ -f /etc/privgroup ]; then
/sbin/init.d/set_prvgrp: /usr/sbin/setprivgrp -f /etc/privgroup

Regards,

Fred

[Vinutha_1]

Hi,

I wanted to know, how it'll affect the database if the dba: MLOCK privillage is not there.