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RE: log buffer space wait

From: <Jared.Still_at_radisys.com>
Date: Wed, 03 Sep 2003 10:29:41 -0800
Message-ID: <F001.005CEA76.20030903102941@fatcity.com>


These are cumalitive times for a few hundred processes.

Jared

<Avnish.Rastogi_at_providence.org>
Sent by: ml-errors_at_fatcity.com
 09/03/2003 10:34 AM
 Please respond to ORACLE-L  

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
        cc: 
        Subject:        RE: log buffer space wait


I have one question regarding these wait times, may be dump. In the following wait events what is the unit of measurement for Time, I believe its in seconds as per the documentation. If yes then here stats are collected for only 51.23 Minutes (Appx 3073 seconds), how come Oracle is showing 566,516 seconds wait for log buffer space. I would appreciate if someone can explain.  

Thanks    

Top 5 Timed Events

~~~~~~~~~~~~~~~~~~                                                     % 
Total
Event                                               Waits    Time (s) Ela 
Time
-------------------------------------------- ------------ -----------

log buffer space                                1,817,258     566,516 
56.24
latch free                                      2,964,652     334,120 
33.17
log file sync                                      55,230      43,488 4.32
buffer busy waits                                  62,839      26,129 2.59
CPU time
-----Original Message-----

Sent: Tuesday, September 02, 2003 6:39 AM To: Multiple recipients of list ORACLE-L

At a Benchmark a particular Processing + DML intensive batch Job (Accounts Interest Calculation) is experiencing
"log buffer space" wait .  

Config :-
On Solaris 9
Cpu_count = 72
Oracle 9.2
Online Redo logfiles are on a RAID 0+1 Volume (NOT Raw or RAID 1) Log_buffer = 10 M
$ sar Command Outpuit %wio only about 6 % for Volume containing the redo logfiles
Database in NOARCHIVELOG mode  

Qs. How can we reduce this wait event ? Would RAW / RAID 1 for redo logfiles help ?
Qs. Could this be a Bug ?  



STATSPACK report for  

DB Name DB Id Instance Inst Num Release Cluster Host
------------ ----------- ------------ -------- ----------- -------


BM2           3727568246 bm2                 1 9.2.0.3.0   NO      sleepy
 
            Snap Id     Snap Time      Sessions Curs/Sess Comment
            ------- ------------------ -------- --------- 

-------------------
Begin Snap: 240 01-Sep-03 03:09:41 23 1.5 End Snap: 241 01-Sep-03 04:00:55 24 1.7 Elapsed: 51.23 (mins) Top 5 Timed Events ~~~~~~~~~~~~~~~~~~ % Total Event Waits Time (s) Ela
Time
-------------------------------------------- ------------ -----------

log buffer space                                1,817,258     566,516 
56.24
latch free                                      2,964,652     334,120 
33.17
log file sync                                      55,230      43,488 4.32
buffer busy waits                                  62,839      26,129 2.59
CPU time                                                       22,018 2.19
          -------------------------------------------------------------

Wait Events for DB: BM2 Instance: bm2 Snaps: 240 -241

-> s  - second
-> cs - centisecond -     100th of a second
-> ms - millisecond -    1000th of a second
-> us - microsecond - 1000000th of a second
-> ordered by wait time desc, waits desc (idle events last)
 
                                                                   Avg
                                                     Total Wait   wait 
Waits
Event                               Waits   Timeouts   Time (s)   (ms) 
/txn
---------------------------- ------------ ---------- ---------- ------

log buffer space                1,817,258        139    566,516    312 
54.4
latch free                      2,964,652    892,594    334,120    113 
88.8
log file sync                      55,230     21,210     43,488    787  
1.7
buffer busy waits                  62,839     10,250     26,129    416  
1.9    

Latch Activity for DB: BM2 Instance: bm2 Snaps: 240 -241  

                                           Pct    Avg   Wait   Pct
                              Get          Get   Slps   Time       NoWait 
NoWait
Latch                       Requests      Miss  /Miss    (s)     Requests  
Miss
------------------------ -------------- ------ ------ ------ ------------

post/wait queue                  97,357    4.7    0.4    577    1,871,155 
249.5
process allocation                  751    7.2    3.0     10          747  
 0.5
process group creation            1,502    0.0             0            0
redo allocation              24,482,283   13.5    0.4 ######            0
redo copy                       675,177   99.6    1.1 ######   21,986,833 
708.0  

init.ora Parameters for DB: BM2 Instance: bm2 Snaps: 240 -241  

                                                                  End 
value
Parameter Name                Begin value                       (if 
different)
----------------------------- ---------------------------------

_db_block_lru_latches         128
audit_trail                   FALSE
background_dump_dest          /oracle/ora92-64/rdbms/log/bdump
compatible                    9.2.0.3
control_files                 /lbmdb02/bm2/data02/control_01_bm
core_dump_dest                /oracle/ora92-64/rdbms/log/cdump
cursor_sharing                EXACT
cursor_space_for_time         TRUE
db_block_size                 8192
db_cache_size                 1258291200
db_file_multiblock_read_count 32
db_files                      1500
db_keep_cache_size            117440512
db_name                       bm2
db_writer_processes           16
dml_locks                     10000
enqueue_resources             680000
hash_join_enabled             FALSE
java_pool_size                16777216
large_pool_size               16777216
log_buffer                    10485760
log_checkpoint_interval       0
log_checkpoint_timeout        0
log_checkpoints_to_alert      TRUE
max_dump_file_size            10240
max_rollback_segments         4000
nls_date_format               DD-MM-YYYY
open_cursors                  1000
open_links                    4
optimizer_index_cost_adj      15
optimizer_mode                CHOOSE
os_authent_prefix
parallel_max_servers          0
parallel_min_servers          0
processes                     3500
session_cached_cursors        50
sessions                      3855
shared_pool_reserved_size     52428800
shared_pool_size              536870912
sort_area_retained_size       2048576
sort_area_size                12582912
timed_statistics              TRUE
transaction_auditing          FALSE
undo_management               AUTO
undo_tablespace               TBA_UNDO
user_dump_dest                /oracle/ora92-64/rdbms/log/udump
utl_file_dir                  *
          -------------------------------------------------------------
 

End of Report    

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  INET: Jared.Still_at_radisys.com

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Received on Wed Sep 03 2003 - 13:29:41 CDT

Original text of this message

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