Tuning Async IO

Tuning Async IO

Post by BBurtens » Tue, 03 Nov 1998 04:00:00



"AIX 4.x supports AIO for database files created on both file system partitions
and on raw devices.  With AIX 4.x, AIO on raw devices other than VSDs and HSDs
is kernelized, which means that AIX servers are not needed to service the AIO
requests."

So if you are using raw devices you don't need to configure AIO.  The exception
to this is OPS.  You will also need to tune for JFS.

The default values are minservers=1 and maxservers=10.  Oracle recommends
maxservers=10*number of disks accessed simultaneously and
minservers=maxservers/2.

To change:
smit->Devices->Asynchronous I/O->Change/Show Characteristics of Asynchronous
I/O->{MINIMUM|MAXIUM} number of servers

You can verify the existence of these kernel processes by "ps -furoot|grep
kproc".  

Good luck,
Barry

>Subject: Tuning Async IO

>Date: 10/28/98 12:48 Eastern Standard Time

>Does anyone have any history with tuning the AIO parameters in AIX 4.2.1?
>More specifically, with regards to Oracle?  If so, please provide me some
>info as to what the various parameters do, or point me to where I can find
>some good info.

>Thanks
>Roy

 
 
 

Tuning Async IO

Post by Sanchia Bak » Tue, 03 Nov 1998 04:00:00


You'll need a patch for AIX 4.2.1 to enable Asynchronous I/O with Oracle. The patch is IX67978.

Oracle also recommend that the following parameters be set in SMIT:-

max servers to 10 times the number of physical disks
min servers to half of the max servers value

hope this helps

Sanchia
Disclaimer : My opinions are my own