RE: buffer busy waits

["Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>]

Thanks Terry, great article and that is a handy little script you provided in 
your article to check wait events over the last 30 seconds - simple, yet 
powerful.

Yes, the users are complaining - the system "slows to a crawl" occasionally and 
that's when I see the huge numbers of bbws and db file seq. reads.  
Unfortunately, this is on 32 bit windows so I'm limited to 3GB SGA split 
between two instances, unless I use indirect data buffers to access > 3GB 
cache, but I don't have any experience with that and had read about some 
negative experiences with it so I'm a bit hesitant to go there.

Anyone out there using use_indirect_data_buffers and >3GB RAM with Windows?  
Any success/horror stories?

My main focus for now is reducing the I/O required by tuning the SQL/schema.  
One thing I noticed is they have pctfree set to 40 on this huge table so I'm 
going to see if I can change pctfree to 5 and cram 35% more data into each 
block.

Thanks again,
Brandon


-----Original Message-----
From: Terry Sutton [mailto:terrysutton@xxxxxxx]

. . .

I described a situation similar to this in a paper a while back
(http://www.dbspecialists.com/presentations/wait_events2.html)

. . .


----- Original Message ----- 

I have a 9.2.0.6 database with the following top 5 timed events from
statspack over a period of 396 minutes:

Top 5 Timed Events
~~~~~~~~~~~~~~~~~~                                                     %
Total
Event                                               Waits    Time (s) Ela
Time
-------------------------------------------- ------------ ----------- ------
--
buffer busy waits                               8,911,867      77,134
37.62
db file sequential read                         3,991,319      59,535
29.03
CPU time                                                       32,274
15.74
 
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