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oracle dba


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oracle dba

  1. 1. T3 is an optimized protocol used to transport data between WebLogic Server andother Java programs,including clients and other WebLogic Servers. WebLogicServer keeps track of every Java VirtualMachine (JVM) with which it connects, and creates a single T3 connection tocarry all traffic for a JVM.For example, if a Java client accesses an enterprise bean and a JDBC connectionpool on WebLogic Server, a single network connection is established betweenthe WebLogic Server JVM and the client JVM.Oracle Support NOTE 1465038.1, “Calculating Usable Space in Exadata Cell“[grid@dodpdb04 ~]$ asmcmd -p (shows present working directory)ASMCMD [+] > lsdgState Type Rebal Sector Block AU Total_MB Free_MBReq_mir_free_MB Usable_file_MB Offline_disks Voting_files NameMOUNTED NORMAL N 512 4096 4194304 36384768 159249083307706 6308601 0 N DATA_DODP/MOUNTED NORMAL N 512 4096 4194304 2087680 303648257400 23124 0 Y DBFS_DG/MOUNTED NORMAL N 512 4096 4194304 9090816 6850084826437 3011823 0 N RECO_DODP/ASMCMD [+] > du DATA_DODP/Used_MB Mirror_used_MB10228996 20458476So the disk redundancy is normal... in DATA_DODP[grid@dodpdb04 ~]$ echo "36384768-20458476" |bc15926292which is pretty close with Free_MBThe free MB divided by 2 (normal redundancy)[grid@dodpdb04 ~]$ echo "15926292/2"|bc7963146which close to Usable_file_MB , the space available new files[grid@dodpdb04 ~]$ asmcmd du DATA_DODP/ ( asm commands non-interactive mode)Used_MB Mirror_used_MB10228996 20458476ASMCMD is very slow. How can I speed it up?The asmcmd utility appears to be very slow. This slowness is a result of queriesagainst the v$asm_diskgroup view. To solve this problem edit the$ORACLE_HOME/bin/asmcmdcore script and change all v$asm_diskgroup references tov$asm_diskgroup_stat.V$asm_diskgroup and v$asm_diskgroup_stat provides exactly the same information,but the %_stat view operates from cache, while v$asm_diskgroup rescans all diskheaders. This method is also used by Oracle in their Enterprise Manager product.What is SYSASM role?Starting from Oracle 11g, SYSASM role can be used to administer the ASMinstances. You can continue using SYSDBA role to connect to ASM but it willgenerate following warning messages at time of startup/shutdown, createDiskgroup/add disk, etcAlert entryWARNING: Deprecated privilege SYSDBA for command STARTUP
  2. 2. How can we copy the files from/to ASM?You can use RMAN or DBMS_FILE_TRANSFER.COPY_FILE procedure to copy the filesto/from ASM from/to Filesystem.Same size disk for Failuregroups in Normal/High redundancy will prevent issueslike ORA-15041 as the file extents needs to be mirrored across the disks I have created Oracle database using DBCA and having a different home for ASMand Oracle Database. I see that listener is running from ASM_HOME. Is itcorrect?This is fine. When using different home for ASM, you need to run the listenerfrom ASM_HOME instead of ORACLE_HOME.How does one create a database directly on ASM?The trick is to create an SPFILE and restart the instance before issuing theCREATE DATABASE statement:Code:STARTUP NOMOUNT PFILE=initorcl_0.oraCREATE SPFILE FROM pfile=initorcl_0.ora;SHUTDOWN IMMEDIATESTARTUP NOMOUNTPoint all OMF files into ASM:Code:ALTER SYSTEM SET db_create_file_dest = +DATA;ALTER SYSTEM SET DB_RECOVERY_FILE_DEST_SIZE = 134G;ALTER SYSTEM SET db_recovery_file_dest = +RECOVER;Issue the create database command:Code:CREATE DATABASE orclUNDO TABLESPACE undotsDEFAULT TEMPORARY TABLESPACE tempcharacter set "WE8ISO8859P1"national character set "AL16UTF16";ASM Instance not recognized by DBCA ,why?I had the same error and the way I fixed is by changing TNS_ADMIN value in.bash_profile.Old ValueTNS_ADMIN=$ORACLE_HOME/network/adminNew ValueTNS_ADMIN=$ASM_HOME/network/adminMy ORACLE_HOME=/d01/app/oracle/product/10.2.0/db_1My ASM_HOME=/d01/app/oracle/product/10.2.0/*asm*Once this is done, I re-executed my .bash_profile and started dbca and the errorwent away.Also, after you create your databse, you might have to set your TNS_ADMIN env insrvctl to start database . Wrong TNS_ADMIN setting might cause the following
  3. 3. errors during the start of database using srvctl but not sqlplus.$ srvctl start database -d ProdDbPRKP-1001 : Error starting instance ProdDb on node node1CRS-0215: Could not start resource ora.ProdDb.ProdDb1.inst.PRKP-1001 : Error starting instance ProdDb2 on node node2CRS-0215: Could not start resource ora.ProdDb.ProdDb2.inst.For example:srvctl setenv database -d ProdDb -TTNS_ADMIN=/d01/app/oracle/product/10.2.0/asm/network/adminWhich shows you that all you need is an +ASM entry in the tnsnames.ora fileunder /d01/app/oracle/product/10.2.0/db_1/network/admin.Bigfile vs standard db filesThe performance of database opens, checkpoints, and DBWR processes shouldimprove if data is stored in bigfile tablespaces instead of traditionaltablespaces. However, increasing the datafile size might increase the time torestore a corrupted file or create a new oracle 11g release 2, instances register with SCAN listeners only as remotelisteners. In your case it should beREMOTE_LISTENER=<scan-name>:<port>That is the purpose of REMOTE_LISTENERExplaination about each parameter in Data Guard1.LOG_ARCHIVE_CONFIG ={ [ SEND | NOSEND ] [ RECEIVE | NORECEIVE ] [ DG_CONFIG=(remote_db_unique_name1 [, ... remote_db_unique_name9) |NODG_CONFIG ] SEND -log files RECEIVE =log file database that are part of data guard configuration 2.Do not use the default value, VALID_FOR=(ALL LOGFILES, ALL_ROLES), forlogical standby databases. log_archive_dest_state_2=DEFER/ENABLE; 3.fal_server and fal_client are used for smooth switch over 4.standby configuration should have one more standby redo log file group thanthe number of online redo log file groups on the primary database. Because, Logical standby databases may require more standby redo log files (oradditional ARCn processes) depending on the workload. This is because logicalstandby databases also write to online redo log files, which take precedenceover standby redo log files. Thus, the standby redo log files may not bearchived as quickly as the online redo log files. Logical standby databases may require more standby redo log files (or
  4. 4. additional ARCn processes) depending on the workload. This is because logicalstandby databases also write to online redo log files, which take precedenceover standby redo log files. Thus, the standby redo log files may not bearchived as quickly as the online redo log files. v$standby_log select member from v$logfile where type=STANDBY; RMAN>backup current controlfile for standby; 5.cp orapwprimary orapwstandby Rename the password file wrt to SID in standby chown -R oracle:oinstall /u01/app will never equals to chown -R oracle:oinstall/u01 scope=both is not valid when database is nomount Error: ORA-12528: TNS:listener: all appropriate instances are blocking newconnections Reason : DB is currently starting up or not available We should have all the archive log files from the backup onwards dorecover clause in the duplicate database means , we have taken a backup at primary as backup database plus archivelog; so oracle will restore the datafiles from backupset and recover usingarchivelog that was backed up. (Anyway once MRP starts it do-recover) Backing Up Logs with BACKUP ... PLUS ARCHIVELOGYou can add archived redo logs to a backup of other files by using theBACKUP ... PLUS ARCHIVELOG clause. Adding BACKUP ... PLUS ARCHIVELOG causes RMANto do the following:Runs the ALTER SYSTEM ARCHIVE LOG CURRENT command.Runs BACKUP ARCHIVELOG ALL. Note that if backup optimization is enabled, thenRMAN skips logs that it has already backed up to the specified device.Backs up the rest of the files specified in BACKUP command. ( if it is adatabase ,then complete database)Runs the ALTER SYSTEM ARCHIVE LOG CURRENT command.Backs up any remaining archived logs generated during the backup.Why we need a standby control file backupStandby controlfile set a flag with that DB identify the DB in standby or NormalDatabase.The controlfile Must be created after the backup of the datafiles.restore standby controlfile from C:ORACLECONTROL08N3GEA6_1_1.BKP;Even if the above control file is creating using current controlfile.
  5. 5. If you have ILOM, you can view the progress of restart through its interface.ssh/SP/start consoleASMDeactivationOutcome??????This attribute shows whether the grid disk can be deactivated without loss ofdata. A value of “Yes“ indicates you can deactivate this grid disk without dataloss.CellCLI> list griddisk attributes name, ASMDeactivationOutcome, ASMModeStatuscrsctl status resource -t??? is it same as crs_stat -tHash join (small table ,large table) is also called as bloom filter.Exadata is kind of "different Oracle", for example it doesnt require indexingon table that much and so and so.An exdata DBA need experience in Database, Storage and OS.A good understanding of SmartScan and Hybrid Columnar Compression. (ctrieb)If you can answer the question "Why with Exadata do I probably not need [some orall of my] indexes?" you are on the right road. (Dan Morgan).Learn all you can about direct path reads as they are critical to enable smartscan. Serial direct path reads are done often in 11gR2, probably because ofExadata influence.Learn about parallel query and the mechanisms available to throttle it (queuingis now available in 11gR2).Knowing something about Infiniband would probably be a good idea as well sinceyoull have to figure out how to connect to external devices (tape drives forexample). Look at the cssd.log files on both nodes; usually we will get moreinformation on the second node if the first node is evicted. Also take a look atcrsd.log file too2. The evicted node will have core dump file generated and system rebootinfo.3. Find out if there was node reboot , is it because of CRS or others, checksystem reboot time4. If you see “Polling“ key words with reduce in percentage values incssd.log file that says the eviction is probably due to Network. If you see“Diskpingout“ are something related to -DISK- then, the eviction is because ofDisk time out.Storage access and private interconnect use different ,Diagnostic information about CRS in $CRS_HOMEcrsctl debug trace{css|crs|evm} enables tracing for the given process
  6. 6. crs_startcrs_start is used to start resources, either one at a time or for the entirecluster.To start all resources across a cluster, the crs_start command can be used withthe -all option:$ crs_start -allcrsctl stop all