LinuxQuestions.org
Did you know LQ has a Linux Hardware Compatibility List?
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - General
User Name
Password
Linux - General This Linux forum is for general Linux questions and discussion.
If it is Linux Related and doesn't seem to fit in any other forum then this is the place.

Notices



Reply
 
Search this Thread
Old 01-13-2012, 11:08 AM   #1
rajaniyer123
Member
 
Registered: Feb 2004
Location: BARODA, GUJARAT
Posts: 259

Rep: Reputation: 30
High I/O wait observed in Linux based Oracle Database Server


Hi,

We have just migrated Oracle Database from Solaris Server to Linux VM [ESX] server.

We have observed that there is high I/O wait issues while database query is running on Linux VM, which was ideally zero in case of Solaris.

In the same ref. please let me know, is there any tunning need to be done from linux side.

Please suggest.
 
Old 01-13-2012, 11:26 AM   #2
TB0ne
Guru
 
Registered: Jul 2003
Location: Birmingham, Alabama
Distribution: SuSE, RedHat, Slack,CentOS
Posts: 15,102

Rep: Reputation: 2719Reputation: 2719Reputation: 2719Reputation: 2719Reputation: 2719Reputation: 2719Reputation: 2719Reputation: 2719Reputation: 2719Reputation: 2719Reputation: 2719
Quote:
Originally Posted by rajaniyer123 View Post
Hi,
We have just migrated Oracle Database from Solaris Server to Linux VM [ESX] server.

We have observed that there is high I/O wait issues while database query is running on Linux VM, which was ideally zero in case of Solaris. In the same ref. please let me know, is there any tunning need to be done from linux side.
Please suggest.
No idea, since there aren't enough details. Solaris probably wasn't running on a VM, and you don't tell us anything about how big that box was (CPU/Memory/disk/etc.), and you don't tell us what version/distro of Linux, or how you have the VMware box set up, and what resources you have assigned to that instance, or how big the database is, and on what kind of disk it's running and how many spindles.

Check the outputs of iostat/sar/top, and see what usages you're getting. Check the Oracle installation docs, and make sure you followed them for Linux installation.

Best thing to do would be to call Oracle support, since you're paying for it. They can run traces, and tell you where the bottleneck is.
 
Old 01-14-2012, 08:51 AM   #3
markseger
Member
 
Registered: Jul 2003
Posts: 241

Rep: Reputation: 25
if you're referring to the CPU time spent in i/o wait, this is probably the most useless number I've ever seen, though I'm happy to be corrected.

My understanding is all this means is the cpu is NOT doing anything while there is I/O going on. In fact in at least collectl, I don't even include it in the total cpu time.

I have done numerous experiments to prove my case. For example, if you fire up a dt (or other disk load generator tool) you'll always see a high i/o wait. If in parallel you start a compute bound process you'll see the iowait drop, since now the cpu has something else to do with its free time.

While I know nothing about solaris, one should be careful not to confuse a counter name from one O/S with another.

-mark
 
1 members found this post helpful.
Old 01-16-2012, 10:00 PM   #4
jlliagre
Moderator
 
Registered: Feb 2004
Location: Outside Paris
Distribution: Solaris10, Solaris 11, Mint, OL
Posts: 9,523

Rep: Reputation: 365Reputation: 365Reputation: 365Reputation: 365
As already pointed by markseger, the i/o wait counter is more confusing than anything useful, especially with modern (multi-core, multi-thread) architectures. That's the reason why Solaris ceased to report anything but zero in it since Solaris 10 (2005).
 
1 members found this post helpful.
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Oracle 10g database installation procedures in redhat Enterprise linux server 5 anoopkjm Red Hat 1 01-13-2011 05:45 AM
LXer: Ubuntu Linux Install Oracle Database XE Server LXer Syndicated Linux News 0 06-30-2007 11:47 PM
Difference between Oracle Server and Oracle Database ganninu Programming 3 02-27-2007 02:06 AM
Oracle 9i + Linux AS 4.0 (64bit) + HP Itanium Based Server rajeevsingh_mumbai Red Hat 3 02-02-2006 12:18 AM
Oracle 9i + Linux AS 4.0 (64bit) + HP Itanium Based Server rajeevsingh_mumbai Linux - Enterprise 1 10-08-2005 12:57 AM


All times are GMT -5. The time now is 03:10 AM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
identi.ca: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration