dean wrote:
> On Aug 13, 11:54 am, "fitzjarr..._at_cox.net" <fitzjarr..._at_cox.net>
> wrote:
>> On Aug 13, 12:10 am, dean <deanbrow..._at_yahoo.com> wrote:
>>
>>
>>
>>
>>
>>> 10g
>>> select * from V$SYSTEM_WAIT_CLASS order by TIME_WAITED desc;
>>> WAIT_CLASS_ID WAIT_CLASS# WAIT_CLASS TOTAL_WAITS TIME_WAITED
>>> ------------- ----------- -------------- ----------- -----------
>>> 2723168908 6 Idle 15742538 990583927
>>> 1740759767 8 User I/O 1501104 541245
>>> 2000153315 7 Network 35587647 227757
>>> 4108307767 9 System I/O 690084 194154
>>> 3386400367 5 Commit 70951 23803
>>> 3875070507 4 Concurrency 11212 13790
>>> 4217450380 1 Application 12112 5730
>>> 1893977003 0 Other 7106 5411
>>> 3290255840 2 Configuration 171 1979
>>> This is the first time I have looked at this view, and I'm trying to
>>> understand it - does this indicate performance issues with the disk i/
>>> o?
>>> Thanks!
>>> Dean
>> Not necessarily; the TIME_WAITED values are in centiseconds (1/100 of
>> a second) and are cumulative for all sessions for as long as the
>> database is running uninterrupted. The User I/O number you posted
>> represents roughly 90 minutes of wait time for ALL sessions since the
>> database started. Presuming you have more than one connected session
>> and that the database has been up and running for more than two hours
>> I'd say no; follow Daniel's advice and file this away for future
>> reference. When and if a user (or group of users) decides to complain
>> about performance you can resurrect these values and compare them to
>> the current numbers (again, presuming you haven't shut down the
>> database between now and then) and possibly find the area or areas
>> which have changed.
>>
>> There is no need to create problems where none currently exist.
>>
>> David Fitzjarrell- Hide quoted text -
>>
>> - Show quoted text -
>
> Ok thanks to both. There is no problem here on the development server,
> I just wanted to familiarize myself. I wasn't sure if this was
> indicating we could use a faster set of drives (forgot it was in
> centiseconds).
These days drives are less relevant as most disk arrays come with a
cache managed by its own operating system.
--
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu (replace x with u to respond)
Puget Sound Oracle Users Group
www.psoug.org
Received on Mon Aug 13 2007 - 11:54:22 CDT
