Oracle Consulting Oracle Training Oracle Support Development
Home
Catalog
Oracle Books
SQL Server Books
IT Books
Job Interview Books
eBooks
Rampant Horse Books
911 Series
Pedagogue Books

Oracle Software
image
Write for Rampant
Publish with Rampant
Rampant News
Rampant Authors
Rampant Staff
 Phone
 800-766-1884
Oracle News
Oracle Forum
Oracle Tips
Articles by our Authors
Press Releases
SQL Server Books
image
image

Oracle 11g Books

Oracle tuning

Oracle training

Oracle support

Remote Oracle

STATSPACK Viewer

Privacy Policy

 

   
 

Oracle Tips by Burleson

Disk I/O Tuning

Chapter 3: SCSI Tuning Under AIX

# chdev -l hdisk8 -a q_type=simple -a queue_depth=24

If the disk array is attached via a SCSI-2 Fast/Wide SCSI adapter bus, it may also be necessary to change the outstanding-request limit for that bus.  Let's look at that next.

Changing AIX Disk Adapter Outstanding-Request Limits

The AIX SCSI-2 Fast/Wide Adapter supports two SCSI buses; one for internal devices and one for external devices.  There is a limit on the total number of outstanding requests that can be defined for each bus.  The default value of that limit is 40 for each bus and the maximum is 128.  When an IBM disk array is attached to a SCSI-2 Fast/Wide Adapter bus, the outstanding-request limit for the bus is increased automatically to accommodate the queue depth of the disk array.  However, for a non-IBM disk array, this change must be performed manually.  For example, using chdev to set the outstanding-request limit of adapter scsi2 to 80, you would use:

# chdev -l scsi2 -a num_cmd_elems=80

Note, if you are using the SCSI-2 High Performance Controller, the maximum number of queued requests is 30 and that limit cannot be changed.  For that reason, you should ensure the sum of the queue depths of the devices attached to a SCSI-2 High Performance Controller does not exceed 30.


The above text is an excerpt from:

Oracle Disk I/O Tuning
Disk IO Performance & Optimization for Oracle Databases
ISBN 0-9745993-4-4 

by Mike Ault
 


Oracle Consulting Services

Burleson Oracle Consulting offers Senior Oracle consultants which are available for all areas of Oracle support.  Common Oracle consulting support activities include short-term Oracle tuning, Oracle database troubleshooting, Oracle9i and Oracle10g migration, Oracle9iAS App Server consulting, Oracle design reviews and Oracle requirements evaluation support. Oracle support and Oracle consulting services are priced by the hour, so you only pay for what you need. These one-time Oracle consulting services commonly include:

  • Answering questions from your Oracle DBA technical staff

  • Repairing down production Oracle database systems

  • One-time Oracle tuning evaluation

  • Guru support for your Oracle DBA

  • Installation of Oracle application packages

For more information, please visit www.rampant-books.com

Linux Oracle commands syntax poster

ION Oracle tuning software

Oracle data dictionary reference poster



Oracle Forum

BC Oracle consulting support training

BC remote Oracle DBA   

 

   

 Copyright © 1996 -2016 by Burleson. All rights reserved.


Oracle® is the registered trademark of Oracle Corporation. SQL Server® is the registered trademark of Microsoft Corporation. 
Many of the designations used by computer vendors to distinguish their products are claimed as Trademarks