on 04-06-2010 9:40 AM
Dear all,
In st04 I see Redo log wait is this a problem. Please suggest how to solve it
Please find the details.
Size (kB) 14,352
Entries 42,123,046
Allocation retries 9,103
Alloc fault rate(%) 0.0
Redo log wait (s) 486
Log files (in use) 8 ( 8 )
DB_INST_ID Instance ID 1
DB_INSTANCE DB instance name prd
DB_NODE Database node A
DB_RELEASE Database release 10.2.0.4.0
DB_SYS_TIMESTAMP Day, Time 06.04.2010 13:07:10
DB_SYSDATE DB System date 20100406
DB_SYSTIME DB System time 130710
DB_STARTUP_TIMESTAMP Start up at 22.03.2010 03:51:02
DB_STARTDATE DB Startup date 20100322
DB_STARTTIME DB Startup time 35102
DB_ELAPSED Seconds since start 1329368
DB_SNAPDIFF Sec. btw. snapshots 1329368
DATABUFFERSIZE Size (kB) 3784704
DBUFF_QUALITY Quality (%) 96.3
DBUFF_LOGREADS Logical reads 5615573538
DBUFF_PHYSREADS Physical reads 207302988
DBUFF_PHYSWRITES Physical writes 7613263
DBUFF_BUSYWAITS Buffer busy waits 878188
DBUFF_WAITTIME Buffer wait time (s) 3583
SHPL_SIZE Size (kB) 1261568
SHPL_CAQUAL DD-cache Quality (%) 95.1
SHPL_GETRATIO SQL area getratio(%) 98.4
SHPL_PINRATIO SQL area pinratio(%) 99.9
SHPL_RELOADSPINS SQLA.Reloads/pins(%) 0.0042
LGBF_SIZE Size (kB) 14352
LGBF_ENTRIES Entries 42123046
LGBF_ALLORETR Allocation retries 9103
LGBF_ALLOFRAT Alloc fault rate(%) 0
LGBF_REDLGWT Redo log wait (s) 486
LGBF_LOGFILES Log files 8
LGBF_LOGFUSE Log files (in use) 8
CLL_USERCALLS User calls 171977181
CLL_USERCOMM User commits 1113161
CLL_USERROLLB User rollbacks 34886
CLL_RECURSIVE Recursive calls 36654755
CLL_PARSECNT Parse count 10131732
CLL_USR_PER_RCCLL User/recursive calls 4.7
CLL_RDS_PER_UCLL Log.Reads/User Calls 32.7
TIMS_BUSYWT Busy wait time (s) 389991
TIMS_CPUTIME CPU time session (s) 134540
TIMS_TIM_PER_UCLL Time/User call (ms) 3
TIMS_SESS_BUSY Sessions busy (%) 0.94
TIMS_CPUUSAGE CPU usage (%) 2.53
TIMS_CPUCOUNT Number of CPUs 4
RDLG_WRITES Redo writes 1472363
RDLG_OSBLCKWRT OS blocks written 54971892
RDLG_LTCHTIM Latching time (s) 19
RDLG_WRTTIM Redo write time (s) 2376
RDLG_MBWRITTEN MB written 25627
TABSF_SHTABSCAN Short table scans 12046230
TABSF_LGTABSCAN Long table scans 6059
TABSF_FBYROWID Table fetch by rowid 1479714431
TABSF_FBYCONTROW Fetch by contin. row 2266031
SORT_MEMORY Sorts (memory) 3236898
SORT_DISK Sorts (disk) 89
SORT_ROWS Sorts (rows) 5772889843
SORT_WAEXOPT WA exec. optim. mode 1791746
SORT_WAEXONEP WA exec. one pass m. 93
SORT_WAEXMULTP WA exec. multipass m 0
IEFF_SOFTPARSE Soft parse ratio 0.9921
IEFF_INMEM_SORT In-memory sort ratio 1
IEFF_PARSTOEXEC Parse to exec. ratio 0.9385
IEFF_PARSCPUTOTOT Parse CPU to Total 0.9948
IEFF_PTCPU_PTELPS PTime CPU / PT elps. 0.1175
Regards,
Kumar
Addition to Mark's update:
Important note for Oracle 10gr2 and beyond: Per MOSC note 351857.1, starting in release 10.2 and beyond, Oracle will automatically size the log_buffer on your behalf and log_buffer cannot be changed dynamically. The automatic log_buffer sizing is based on the granule size (as determined by to ksmggranule_size):
Then no need to worry about your current size of log_buffer....
Regards,
Nick Loy
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Are you facing any real performance issue?
Regards,
Nick Loy
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Dear All,
thanks , as we have just upgraded from ecc5 to ecc6 and i need to be sure that every thing is ok.the present redo log wait is
Size (kB) 14,352
Entries 54,174,526
Allocation retries 9,752
Alloc fault rate(%) 0.0
Redo log wait (s) 509
Log files (in use) 8 ( 8 )
Please suggest how to check up which value it is ok and above that we need to take any action.
Regards,
Kumar
Hi,
10g R2 the log_buffer is managed for you by Oracle....
The log redo wait looks not bad for the time it's been up.
Have you a particular problem ?
Mark
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Hi,
If the redo buffers are not large enough, the Oracle log-writer process waits for space to become available. This wait time becomes wait time for the end user. Hence this may cause perfromance problem at database end and hence need to be tuned.
The size of the redo log buffer is defined in the init.ora file using the 'LOG_BUFFER' parameter. The statistic 'redo log space requests' reflects the number of times a user process waits for space in the redo log buffer.
If the size of redo log buffer is not big enough causing this wait, recommendation is to increase the size of redo log buffer in such a way that the value of "redo log space requests" should be near to zero.
regards,
rakesh
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14251008 = 13 MB. More than usually recommended (1MB for normal database ).
The value of log_buffer must be a multiple of redo block size (normally 512 bytes)
Too-small log_buffer size indicated by wait event "redo log space requests" and a too-large log_buffer may be indiacted by high value "log file sync" event. You need to monitor these wait event to determine wherether to increase it further.
Also, it depends on type of your database. In heavily update intensive database no matter what you do there would be redo log wait.
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