Exadata: Configuring SSH Equivalency to use dcli

Exadata comes with many storage servers, The Cell Administration can be done on the command line as user celladmin with CellCLI,but it would be an annoying task to do all commands many times. Therefore, dcli was introduced to enable us to control multiple Cells with a single command for which you have to configure the SSH.

Exadata: Physical Disks, LUNs, and Cell Disks Mapping

As an Exadata DMA, you should know to map the physical disks in an Exadata Storage Server to Logical Units (LUNs) and map LUNs to Exadata cell disks in order to understand how Exadata’s disks are presented as usable storage entities.

Exadata: Locating Oracle Cluster Registry and Voting Disks

On Exadata, Oracle has elected to store the Oracle Cluster Registry (OCR) and voting disks on Oracle ASM disk groups, mapped to Exadata storage server grid disks. The OCR and voting disks are typically stored in the DBFS_DG ASM disk group and associated grid disks.

How to load flat files containing Arabic (any non-English) characters using SQLLDR

When you need to load non-ASCII data from a flat file into an Oracle database, the primary tool of choice is SQL*Loader, but unfortunately it does not automatically recognize the character encoding scheme of non-ASCII text (Arabic) files, you have to specify the correct encoding for the flat file in order to ensure a successful load. For that purpose, NLS_LANG needs to be set before launching SQL*Loader. If encoding type of the flat file is unknown, unfortunately there is no 100% reliable way to determine what encoding is used in that text file.

ORA-01704: String Literal Too Long. Cause: String Literal is Longer Than 4000 Characters

A text literal can have a maximum length of 4000 bytes.  In order to update a column greater than 4K, bind variables must be used and in the case of lobs if the data set is greater than 32k, use DBMS_LOB for piece wise manipulation.

Exadata: Restoring OCR and Vote Disks

Oracle allows you to restore your Oracle Cluster Registry using the ocrconfig –restore command. This command accepts a backup OCR file as its argument, which you can choose by running ocrconfig –showbackup and selecting the appropriate backup copy that resides on your compute node file system.

Getting Flash Storage info

Exadata flash storage is provided by Sun Flash Accelerator F20 PCI flash cards. Each PCI flash card has a device partitioned per FDom, yielding 16 flash devices. These flash devices are manifested as ExadataStorage Server flash disks and used for Smart Flash Cache and Smart Flash Logging.

Getting Disk Storage Details on the Exadata Storage Servers

If you want to know how storage is allocated, presented, and used in the Exadata storage cell, use below commands to get the related information.

Getting Storage Server Architecture Details

Exadata Storage Servers are self-contained storage platforms that house disk storage for an Exadata Database Machine and run Oracle’s Cell Services (cellsrv) software. A single storage server is also commonly referred to as a cell.

Restoring OCR and Vote (11gR2 Linux)

Restoring OCR from backup

Testing Scenario: 

OCR is located on +OCR_VOTE diskgroup which was created with external redundancy, 

OCRVOTE is corrupted or diskgroup where OCRVOTE is located has problem.

Fact Sheet - Hekaton - TimesTen

Upon the request of one of my friend, below is the quickly prepared fact sheet for Microsoft's Hekaton and Oracle's TimesTen, will be updated more soon.

Setting up Data Guard 11gR2 (RAC to RAC)

Purpose: 
Setting the Data Guard for RAC primary to RAC Standby.

Assumptions:
1- Primary site has 2 Node RAC 11gR2 installation on Oracle Linux 5.6. Primary database name is PROD
2- Standby site has Oracle GI 11gR2 with RDBMS software only installation on Linux 5.6 on 2 node Linux 5.6. Standby database name will be STAN.

RMAN: Tape backups as Expired while files physically exist

Sometimes all current backups are marked as expired when performing a crosscheck backup while backupsets physically exist and these backupsets are not expired according to Media Manager like Legato or Netbackup. You should first check the Parms used in allocate channel command are correct, if they are correct you should enable the debug for RMAN for more details.
RMAN> DEBUG ON;

RMAN> ALLOCATE CHANNEL FOR MAINTENANCE DEVICE TYPE 'sbt_tape' SEND 'NB_ORA_CLIENT=OR-11, NB_ORA_SERV=mg-2' trace 1;

RMAN> crosscheck backup;
RMAN> DEBUG OFF;

Check sbtio.log in user_dump_dest location which will have the errors during the time of crosscheck.

Possible Reasons:

1- Some times errors are due to the SBT library, enabling debug can provide more insight.

2- CROSSCHECK was run with the wrong PARMS settings. RMAN will query the media manager and get response back that the backup piece cannot be found. It will then set the status of the piece to Expired.

RMAN doesn't have a concept of what media manager it is using. As long as you specify device type SBT, it's up to the user to make sure that the configuration and PARMS settings are correct. RMAN will just query the media manager generically, as it only knows that the backup was made to SBT.

12c: EM: OMS Server Fails - error nm home replaced

Environment: Oracle Enterprise Manager 12c, Windows 2008 R2
Error:Below error occured on one of the client environment
C:\Windows\system32>%OMS_HOME%/bin/emctl start oms
Oracle Enterprise Manager Cloud Control 12c Release 3
Copyright (c) 1996, 2013 Oracle Corporation. All rights reserved.
Windows service OracleManagementServer_EMGC_OMS1_1 failed to be started
Oracle Management Server is Down
Please check E://gc_inst/em/EMGC_OMS1\sysman\log\emctl.log for error details


Log file showed below

2013-12-22 10:30:54,300 [main] INFO wls.OMSController main.219 - Executing emctl command : start
2013-12-22 10:30:58,536 [main] INFO commands.BaseCommand getEnvProps.456 - nm home replaced : E:/gc_inst/NodeManager/emnodemanager
2013-12-22 10:30:58,581 [main] INFO commands.StartCommand startOMS.371 - net start return code is 2
2013-12-22 10:30:58,582 [main] ERROR commands.BaseCommand logAndPrint.620 - Windows service OracleManagementServer_EMGC_OMS1_1 failed to be started
2013-12-22 10:31:00,653 [main] INFO commands.BaseCommand printMessage.404 - statusOMS finished with result: 8

Solution:
1- Check Repository Database and Listener are up and running and Repository database is registered with the listener (lsnrctl services), start the Repository Database and its listener if required.

2- Check you can connect to Repository Database as 'SYSMAN' using SQLPLUS.

3- Shutdown the OMS

C:\Windows\system32>%OMS_HOME%/bin/emctl stop oms -force
Oracle Enterprise Manager Cloud Control 12c Release 3
Copyright (c) 1996, 2013 Oracle Corporation. All rights reserved.
Stopping WebTier...
WebTier Successfully Stopped
Stopping Oracle Management Server...
Node Manager Not Running
Oracle Management Server is Down

4- Start the OMS

C:\Windows\system32>%OMS_HOME%/bin/emctl start oms

Oracle Enterprise Manager Cloud Control 12c Release 3

Copyright (c) 1996, 2013 Oracle Corporation.  All rights reserved.

Windows service OracleManagementServer_EMGC_OMS1_1 successfully started

Oracle Management Server is Up

Exadata: Hybrid Columnar Compression & Considerations

Brief:

Exadata Hybrid Columnar Compression (EHCC) is a type of segment compression. With HCC, data is organized for storage by columns for a set of rows, this collection of groups of rows organized and compressed together is what leads to the “hybrid” tag. 

Exadata: Migration Considerations and Strategies

Once the Exadata Machine is ready, you are ready to migrate your data from your legacy hardware to Exadata. Please note that there is no difference between data segments stored in Exadata Storage Server cells and those in conventional storage unless Exadata Hybrid Columnar Compression (EHCC) is being used.  So you can use the same tools and techniques that you normally use for migration of non-Exadata systems but with some considerations. 

RMAN: Incremental Backup

Below explains a method which can be used to restore oracle incremental level backup to restore rman backups on new server to  significantly reduce restore time.
Following steps are involved.

Exadata: Storage Indexes

Brief: 
Storage Indexes are not indexes that are stored in the database like Oracle’s traditional B-Tree or bitmapped indexes. A storage index is a memory-based (heap of cellsrv) structure and its purpose is to tell Oracle with absolute certainty that a requested extent does not exist in specific locations, and Exadata uses this information to bypass I/O requests to the physical storage locations. 

Exadata: Shuting down/Rebooting cell without affecting ASM

Sometimes it becomes necessary to power down or reboot the cell to perform maintenance while one or more databases are running. In this situation You need to verify that taking the storage server offline will not impact Oracle ASM disk group and database availability. The ability to take Oracle Exadata Storage Server offline without affecting database availability depends on the level of Oracle ASM redundancy used on the affected disk groups, and the current status of disks in other Oracle Exadata Storage Servers that have mirror copies of data as Oracle Exadata Storage Server to be taken offline.

Exadata: Calculating Reserve Space for Cell/Disk Failure Coverage

ASM disk groups in Exadata are defined as either normal or high redundancy. Normal redundancy provides for two copies of file extents while high redundancy provides for three copies of file extents. Each disk is partnered with a set of other disks in other failure groups to ensure that file extent copies are stored in separate failure groups and the disk group can tolerate the loss of one disk (or one cell) in normal redundancy or two disks (or two cells) in high redundancy disk groups.