473,320 Members | 2,117 Online
Bytes | Software Development & Data Engineering Community
Post Job

Home Posts Topics Members FAQ

Join Bytes to post your question to a community of 473,320 software developers and data experts.

DB2 and CIO DIO on AIX

1
Hi Guys,

I just wondering whether is really worthwhile enabling CIO for DB2. The reason behing my question is under JFS2 and file system buffering you can basically take advantage of readahead_max_pages which makes a huge difference when performing large read sequential (e.g database backup or even large joins suh as the one's common on a datawarehouse ). My impresion is that once CIO is enable it'll use DIO implicitly therefore all reads/writes will be done synchronously unless the data is already in the db2 bufferpool. I wonder if anyone else who has implemented CIO DIO for DB2 can share their experience regardless they were positive or negative. thanks in advance.

Harby.
Nov 17 '08 #1
1 5305
G'day Mate,

Since Concurrent I/O implicitly invokes Direct I/O, all the performance considerations for Direct I/O hold for Concurrent I/O as well. Thus, applications that benefit from filesystem read-ahead, or have a high filesystem buffer cache hit rate, would probably see their performance deteriorate with Concurrent I/O, just as it would with Direct I/O. On AIX 5.2.10, Concurrent I/O is the preferred method since it is not subject to the limitations of buffer size and alignment that limit Direct I/O’s effectiveness on JFS and pre AIX 5.2.10 JFS2 file systems. The benefits of Direct I/O and Concurrent I/O with DB2 are evident in:

• Disk throughput
• System CPU utilization
• Memory usage

With Direct I/O and Concurrent I/O, overall performance improvements are largely a result of the freeing up system CPU cycles for use by the application. On I/O bound systems, the performance gain is less dramatic since the application is waiting on data from the disks to continue processing and any extra CPU cycles are wasted

You might have to look over this article for details.
http://www3.software.ibm.com/ibmdl/p...IO-article.pdf

Thanks,
Shashank K
IBM, DB2 for Linux, Unix & Windows -Information Management Software
Dec 17 '08 #2

Sign in to post your reply or Sign up for a free account.

Similar topics

3
by: William C. White | last post by:
Does anyone know of a way to use PHP /w Authorize.net AIM without using cURL? Our website is hosted on a shared drive and the webhost company doesn't installed additional software (such as cURL)...
2
by: Albert Ahtenberg | last post by:
Hello, I don't know if it is only me but I was sure that header("Location:url") redirects the browser instantly to URL, or at least stops the execution of the code. But appearantely it continues...
3
by: James | last post by:
Hi, I have a form with 2 fields. 'A' 'B' The user completes one of the fields and the form is submitted. On the results page I want to run a query, but this will change subject to which...
0
by: Ollivier Robert | last post by:
Hello, I'm trying to link PHP with Oracle 9.2.0/OCI8 with gcc 3.2.3 on a Solaris9 system. The link succeeds but everytime I try to run php, I get a SEGV from inside the libcnltsh.so library. ...
1
by: Richard Galli | last post by:
I want viewers to compare state laws on a single subject. Imagine a three-column table with a drop-down box on the top. A viewer selects a state from the list, and that state's text fills the...
4
by: Albert Ahtenberg | last post by:
Hello, I have two questions. 1. When the user presses the back button and returns to a form he filled the form is reseted. How do I leave there the values he inserted? 2. When the...
1
by: inderjit S Gabrie | last post by:
Hi all Here is the scenerio ...is it possibly to do this... i am getting valid course dates output on to a web which i have designed ....all is okay so far , look at the following web url ...
2
by: Jack | last post by:
Hi All, What is the PHP equivilent of Oracle bind variables in a SQL statement, e.g. select x from y where z=:parameter Which in asp/jsp would be followed by some statements to bind a value...
3
by: Sandwick | last post by:
I am trying to change the size of a drawing so they are all 3x3. the script below is what i was trying to use to cut it in half ... I get errors. I can display the normal picture but not the...
0
by: DolphinDB | last post by:
Tired of spending countless mintues downsampling your data? Look no further! In this article, you’ll learn how to efficiently downsample 6.48 billion high-frequency records to 61 million...
0
by: ryjfgjl | last post by:
ExcelToDatabase: batch import excel into database automatically...
0
by: Vimpel783 | last post by:
Hello! Guys, I found this code on the Internet, but I need to modify it a little. It works well, the problem is this: Data is sent from only one cell, in this case B5, but it is necessary that data...
0
by: ArrayDB | last post by:
The error message I've encountered is; ERROR:root:Error generating model response: exception: access violation writing 0x0000000000005140, which seems to be indicative of an access violation...
1
by: PapaRatzi | last post by:
Hello, I am teaching myself MS Access forms design and Visual Basic. I've created a table to capture a list of Top 30 singles and forms to capture new entries. The final step is a form (unbound)...
1
by: CloudSolutions | last post by:
Introduction: For many beginners and individual users, requiring a credit card and email registration may pose a barrier when starting to use cloud servers. However, some cloud server providers now...
1
by: Defcon1945 | last post by:
I'm trying to learn Python using Pycharm but import shutil doesn't work
1
by: Shællîpôpï 09 | last post by:
If u are using a keypad phone, how do u turn on JavaScript, to access features like WhatsApp, Facebook, Instagram....
0
by: af34tf | last post by:
Hi Guys, I have a domain whose name is BytesLimited.com, and I want to sell it. Does anyone know about platforms that allow me to list my domain in auction for free. Thank you

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.