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Home -> Community -> Mailing Lists -> Oracle-L -> Re: log buffer space wait
Hi!
What's the value for _log_simultaneous_copies parameter? You might want to manually increase it, even though it depends on CPU_COUNT when left default. I personally would increase log_buffer size as well, if you got that many CPUs and concurrent sessions.
Tanel.
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
-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Tanel Poder INET: tanel.poder.003_at_mail.ee Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Tue Sep 02 2003 - 10:24:28 CDT
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