What Exactly Redo Log File Contains
Oct 1, 2011what exactly redo log file contains.? whether they contained the ddl or dml statements or more than that.........?
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Performance Tuning :: Redo Log File Size
Apr 6, 2011The REDO log file size is important DB performance issues when DB is run archivelog mode.If DB run noarchivelog mode, REDO log file size not impact to DB performance.
View 3 Replies View RelatedServer Administration :: Generation Of Redo Log File
Aug 20, 2010redo generation. As I found the below statement in another forum."Undo segment generates the redo data also, because undo segment is database changes, so it generates the redo data also."
How a Undo segment can generate Redo and Undo datas.
Increased REDO Log File Size To 500m
Aug 31, 2012I have a standalone DB of version 10.2.04.I am facing log file parallel write as one of the top events.I have increased the REDO log file size to 500m.But even then REDO switching is happening frequently.
select group#, bytes, archived, status, first_change#, first_time from v$log order BY first_change#;
GROUP# BYTES ARC STATUS FIRST_CHANGE# FIRST_TIME
---------- ---------- --- ---------------- ------------- ----------
10 262144000 NO INACTIVE 8509999 30-08-2012
12 524288000 NO INACTIVE 8612142 30-08-2012
11 262144000 NO INACTIVE 8676390 30-08-2012
9 262144000 NO CURRENT 8706330 30-08-2012
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Performance Tuning :: Optimal REDO Log File Size
Feb 10, 2011I would like to make a change on the live system!I have read a book and found a information about REDO log file size is impact on DB performance.My DB current log file size is 100 MB. But, Oracle 10g's Redo Logfile Sizing Advisor offer the optimal log file size is 1845 MB.What REDO log file size is best for my Oracle database?
#Optimal log file size:
select optimal_logfile_size
from v$instance_recovery
----------------------------
OPTIMAL_LOGFILE_SIZE
1842
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Performance Tuning :: Wrong REDO Log File Location
Feb 25, 2011I try to current redo log file location to multiplex redo log configuration. I did do this on the DB.I import a backup file to DB when I made this change, but its too slow running import process from old configuration. Approximately it is 4 times slow.
when I recovery old configuration for redo log file, import process is normal running...Why this changes hit to DB import process performance? The old redo log file location is below:
GROUP#MEMBERBYTES
4"/crtest1/oradata/redo04a.log"524288000
4"/crtest1/oradata/redo04b.log"524288000
3"/crtest1/oradata/redo03a.log"524288000
3"/crtest1/oradata/redo03b.log"524288000
2"/crtest1/oradata/redo02a.log"524288000
2"/crtest1/oradata/redo02b.log"524288000
1"/crtest1/oradata/redo01a.log"524288000
1"/crtest1/oradata/redo01b.log"524288000
The new multiplex redo log file location is below:
GROUP#MEMBERBYTES
4"/crtest1/oradata/redo04a.log"524288000
4"/opt/redolog/redo04b.log"524288000
3"/opt/redolog/redo03a.log"524288000
3"/usr/redolog/redo03b.log"524288000
2"/usr/redolog/redo02a.log"524288000
2"/disk1/redolog/redo02b.log"524288000
1"/disk1/redolog/redo01a.log"524288000
1"/crtest1/oradata/redo01b.log"524288000
I think that new configuration is better for old configuration at security issue.Here is the disk partitions on the server:
-bash-3.00$ df -lh
Filesystem size used avail capacity Mounted on
/dev/dsk/c0t0d0s0 9.6G 2.2G 7.3G 23% /
/devices 0K 0K 0K 0% /devices
ctfs 0K 0K 0K 0% /system/contract
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Commit Completes Although Current Online Redo Log File Have Been Removed
Apr 10, 2013Although i have removed current online redo log file in linux os (Oracle Linux),when i type "commit" it says that "commit complete".
Is this fair for this princip?*:" if Only when all redo records associated with a given transaction are safely on disk in the online logs is the user process notified that the transaction has been committed."*
I think that it can lead to loss of data in some cases..I'm using Oracle 11g R2 on OEL (x64)..
P.S : I haven't multiplexed current ORL group files...
Backup & Recovery :: Restore From Newer Control File And Archived Redo Log Files?
Mar 29, 2011I've got a legacy SAP system with oracle 8i on Tru64. No changes at all are made but for legal reasons we have to keep it up and running.
we currently do a full backup monthly by shutting down oracle and doing a backup of all the files to tape and that takes around 12 hours.
If I stop doing the full backup and I only backup the control file and the archived redo log files every month and I had to restore the full database years from now, would I be able to restore the database using the last full monthly backup and use the latest control file and archived redo log files?
Redo Log Sizing
Dec 28, 2012I look after a database that contains GIS mapping data. We do not use Oracle Spatial - it's just a plain Oracle Standard DB. It is running in Noarchivelog mode (I know - it's not a good idea, but will be sorted when our new Sun T4-1 arrives).
There are only a couple of users who actually edit data in the database, but about 100 simultaneous users who access it. In day to day use we have no performance issues. The DB has 3 50Mb redo log groups, and these switch about every hour or so during normal use.
Every few weeks we do a bulk update of our underlying map data. This involves putting about 4Gb of data into the database (which is about 15Gb in total). This takes about 5 hours and whilst I'm sure our old Sun v240 server lacking power is a substantial cause, I think the lack of redo space makes matters worse. Last time we did this, the system clocked just over 200 redo log switches in 5 hours. There were lots of "Checkpoint Incomplete" messages in the log file too.
The software we use to load the map data doesn't allow the data to be loaded with a nologging switch.
I could resize the redo logs, but if I size them for the update workload - 3x 500Mb - we'll have some days where we don't get a redo log switch at all. Is this necessarily a problem?
The alternative I'm thinking of is prior to performing this update, we add an extra redo log group with a 1Gb file, run the update, then remove the redo log group and delete the file afterwards. Is there anything wrong with this approach?
Get Redo-log Group Sizing?
Aug 22, 2012What is the optimal redo log size for the database and how many log files required if desired to enable archive log mode.what can be the value for fast_start_mttr_target..?i think if it this parameter set we can have redo log advisor for optimal redolog size.we have 2 redolog groups with 2 members each size of 1 GB. Will it degrade db performance..?
Database version 11.1.0.7
Oracle apps R12
OS : Linux Redhat 5.5
How To Calculate Redo Rate
Nov 14, 2006how would I be able to calculate the Redo rate for using in the Required bandwidth Formula as seen below :
Required bandwidth Formula ((Redo rate in bytes per second / 0.7) * 8) / 1,000,000 = bandwidth in Mbps
Example: 385 KB/sec peak rate would require an available network bandwidth of at least
((394253 / 0.7) * 8) / 1,000,000 = 4.5 Mbps.
SOURCE OF FORMULA Network Bandwidth Implications of Oracle Data Guard...I'm using Oracle 10g
Advantages Of Redo Log Threads
Sep 16, 2010tell me the advantages of using more than one redo log thread? Currently i am setup with 3 logfile groups and 3 members in each group.Ie
logfile group 1 ('/u01/oradata/pri/redo01a.dbf',
'/u02/oradata/pri/redo01b.dbf',
'/u03/oradata/pri/redo01c.dbf') size 30M,
group 2 ('/u01/oradata/pri/redo02a.dbf',
'/u02/oradata/pri/redo02b.dbf',
'/u03/oradata/pri/redo02c.dbf' ) size 30M,
group 3 ('/u01/oradata/pri/redo03a.dbf',
'/u02/oradata/pri/redo03b.dbf',
'/u03/oradata/pri/redo03c.dbf' ) size 30M
REDO Log Member Multiplex
Jun 13, 2012I wanna know if the redo log members are mirror copies.All member files from a same redo group have the same data?Are there any different in mirror or multiplex a file?
View 4 Replies View RelatedRedo Log Group Resize
Mar 20, 2012I want to re-size redo log group on my production database .i have 10 redo log groups of 50mb each having 2 members.i want 4 redo groups to be of 250 mb each having 2 members and then i will drop that old 10 redo log group(50 mb ) , so that i will have only 4 redo log group of 250MB each having 2 members.But i have physical standby and logical standby configured on production database .
find attached file for redo log configuration of production database(CBSPROD),Logical standby database(CBSMIS), Physical standby database(CBSDR).
Resizing Redo Logs
Aug 8, 2012I'm using Oracle 10gR2 (10.2.0.4.0) 64 bits.
I got many times oracle ORA-00494 error and the database went down but since 29th of july the database have not been killed.
The error message is below :
ORA-00494: mise en file d'attente [CF] d�tenue pendant trop longtemps ( (more than 900 seconds)) par inst 1, osid 176484
ORA-00028: votre session a �t� ferm�e
My database is used for datawarehouse of many terabytes.
Initially the redo log size was 500Mbytes and I've set it to 3Gbytes. The maximum log switch is after 5 minutes. I want log to be switched every 20 minutes or every 30 minutes.
To obtain the size of redo logs I've executed this query :
SQL> select OPTIMAL_LOGFILE_SIZE from v$instance_recovery;
OPTIMAL_LOGFILE_SIZE
--------------------
54763
53,5 Gbytes is it not very big as redo log size? What's the maximum size of redo log? To set very big redo log size what are the requirements? Which precautions should I take before? What are the risks? Are any other ways to change the log switch frequency?
Performance Tuning :: No Redo For DML?
Mar 17, 2006How can I disable redo generation for DML statements.
View 25 Replies View RelatedRedo Generated In Last 2 Hour
Feb 7, 2013Is there any way to get the amount of redo generated in last 2 hour. which has below chareteistic
1. redo generated by currently connected session from last 2 hour.
2. redo generated by session disconnected during last 2 hour.
total_redo = disconnected sessoin during last 2 hour + connected session generating redo during last 2 hour.
Redo Logs Size
May 28, 2013is it Any way I can put the size of my redo log (During Install Oracle DB 11.1.0.7 )
I mean during installtion .??? becouse its by default 50 MB I need to be 200MB
Redo Multiplexing And Archiving
Aug 21, 2012Database version
SQL> select * from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
PL/SQL Release 11.1.0.7.0 - Production
CORE 11.1.0.7.0 Production
TNS for Linux: Version 11.1.0.7.0 - Production
NLSRTL Version 11.1.0.7.0 - Productionredo logs multiplexed.
[code]....
+ when the redolog 5 was archived how the archiving process works ?
let say both the log members are clean in case which one will be archived 5a or 5b ?
+ I can also see only one archive log is creating during log swtich
Redo Log Information - Arch Vs LGWR?
Oct 25, 2012Redo log information can be transmitted in one of two ways from the primary database to the standby database: either by ARCH or LGWR.
1. when ARCH involves
2. when LGWR involves
FAL_Client = (Should i enter net service name or Db name or service_name
FAL_Server = Should i enter net service name or Db name or service_name )
FAL_CLIENT='whichone'
[code]...
Unable To Find Redo Log Files Specified?
Jul 15, 2011I am creating database instance from template. I have specified the location of redo log files. When I run the dbca utility it does creates the redo log files in specified directory. But the installation fails . When I checked the trace file. it says unable to locate the specified file(redo.log). But when i check in directory they are created.
I am using windows 32 bit oracle 11g
DataGuard - Standby Redo Log Files
Sep 3, 2012What is the purpose of Standby Redo Log Files in Data Guard configuration? When it is utilized by the database?
View 4 Replies View RelatedAdd Changed Rows To Redo Log Files
Aug 29, 2012I learned that Oracle uses supplemental logging mechanısm to add the changed rows to redo log files and identify the changed rows on target replication database? Is that mechanism mandatory to handle the replication of data between updated and back up databases?
View 1 Replies View RelatedBackup & Recovery :: Redo Log Volume
May 22, 2011I was asked by my systems administrator if I could tell him how much redo log volume, on average, do I figure we generate in a day?
Just wondering how I might calculate this?
We have several production databases. If I wanted to calculate the above for one of them, would it be take all the redo logs for a day and total up the size in bytes? Maybe take a 5 day work week and take the average over the 5 days?
SQL & PL/SQL :: Redo Log Generated In Materialized View
Dec 17, 2012As we know that, MV is generating more redo logs during the FAST refresh. but i need more clarifications on that.
see the below examples:
exec dbms_mview.REFRESH ( LIST => 'mv_test', method=>'F');
PL/SQL procedure successfully completed.
select a.name, b.value
from v$statname a, v$mystat b
where a.statistic# = b.statistic#
and a.name = 'redo size';
NAME VALUE
---------------------------------------------------------------- ----------
redo size 147144
see the redo size is 147144 bytes. Immediately, i refreshed in MV view. now there is no update or insert or delete stats happened in source tables. but i do see redo log generation is high for NO DATA refresh.
select a.name, b.value-147144
from v$statname a, v$mystat b
where a.statistic# = b.statistic#
and a.name = 'redo size';
NAME VALUE
---------------------------------------------------------------- ----------
redo size 42352
For no rows refresh, it takes 42352 bytes.. why oracle generated redo logs when there is no DML operations happened in source table.
Dirty Versus Redo Buffer?
Mar 3, 2010What's the difference between a dirty buffer and a redo buffer?
My understanding is that a dirty buffer is a changed buffer or whenever data changes in the buffer cache, it's marked as dirty. Also, a redo buffer keeps track of changes that were made to the data, so it's also referring to changed data as well...DWBn writes dirty buffers to disk and LGWR writes redo data to redo log filesHow can we differentiate between the two?
Performance Tuning :: Redo Size?
Jun 18, 2012In one of our envirnoment i could see the redo size is high.Trying to understand why this is more
View 18 Replies View RelatedServer Administration :: Redo Log Generation?
Jul 26, 2010I have oracle 9i running on HP-UX, I would like to find how much redo we are generating in a given period of time, is there any script that I can use to get this information?
View 3 Replies View RelatedServer Administration :: Redo Log Buffer Using?
May 27, 2011I learnt that logWriter writes in the redo log files when redo log buffer is 1/3 full, it means that 66 % of redo log buffer are always empty and never used,
if no, isn't a waste of memory (66 % always empty !)
Smart Flash Cache And Redo With SSD?
Oct 23, 201211.2.0.2.0
OEL.
Design stage of New SAN. I can put a lot of the database, including redo on SSD.
1. Hardware sub tiering enabled. Has anyone ever gauged performance with enabling 11g Smart flash cache using the SSD as the flash device even with the hardware subtiering on? ie, if the hardware subtiering is moving hotblocks to most performant disk, is there much significant benefit having the flash cache on. Im guessing yes as the flash cache is working at the SGA level.
2. To redo or not to redo on SSD. Many notes say not to so as to avoid log file sync waits. Is there a way to keep it on the SSD and avoid the waits? Is there any risk of enhanced degradation of the disks over time with having so much sequential writes from the redo if I leave it on there?
How to Minimise Waits for 'Log File Sync' [ID 857576.1] (discusses keeping redo off ssd but only generally)
[URL]