By Rene Kundersma on Apr 22, 2014
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Recently Oracle published the below video created by our group (MAA team) which demonstrates Exadata's High Availability in the face of hardware and software failures. This video is a great showcase on how Exadata handles hardware and software failures. These are tests Oracle does on a daily basis for Engineered systems so every Exadata customer benefits !
Today I received the news a new demo has been made available on OTN for Data Guard protection from lost-write corruption. Since this is a typical MAA solution and a very nice demo I decided to mention this great feature also in this blog even while it's a recommended best practice for some time.
When lost writes occur an I/O subsystem acknowledges the completion of the block write even though the write I/O did not occur in the persistent storage. On a subsequent block read on the primary database, the I/O subsystem returns the stale version of the data block, which might be used to update other blocks of the database, thereby corrupting it. Lost writes can occur after an OS or storage device driver failure, faulty host bus adapters, disk controller failures and volume manager errors.
In the demo a data block lost write occurs when an I/O subsystem acknowledges the completion of the block write, while in fact the write did not occur in the persistent storage. When a primary database lost write corruption is detected by a Data Guard physical standby database, Redo Apply (MRP) will stop and the standby will signal an ORA-752 error to explicitly indicate a primary lost write has occurred (preventing corruption from spreading to the standby database).
With a very busy time behind and ahead of me, I still like to make mention of a couple of documents recently we published.
OPlan is now available for Linux as well as Solaris X86-64 for the Oracle Exadata Database Machine. The current version of OPlan is 22.214.171.124.5. For more details, see my previous post
The two notes mentioned below explain about how OPlan can be used and demo how OPLan works to clone the Grid Infrastructure on the Database Machine, patch the cloned home and switch to it. This is called out-of-place patching.
Supported software versions for Exadata are still listed in MOS note 888828.1, this is where you will find a reference to the latest Exadata Storage Server software release: 126.96.36.199.5, available via patch 12849110. Please see note 1334254.1 for the details.
For the Database Server, the latest patch made available for 188.8.131.52 is Bundle Patch 10, available via Patch 12773458 (Linux version). Please know that BP's can be applied by EM, which makes patching more easy.
For ASR we now have release version 3.3 Released. Details can be found in Note 1185493.1.
The latest PDU metering unit firmware is 1.04 and available as patch 12871297.
For MAA Best pracitces releated to the database machine we released a real good document called "Oracle Exadata Database Machine Consolidation: Segregating Databases and Roles", which you can find here
Also releated to best practices is the document "MAA Best Practices for
Oracle Exadata Database Machine", you can find that here
Recently an updated version of to the MAA whitepaper "Oracle GoldenGate on Oracle Exadata Database Machine Configuration" has been made available. With this update new information is added regarding:
Also a new document is published called "Disaster Recovery for Oracle Exalogic Elastic Cloud with Oracle Exadata Database Machine". This document discusses :
With this entry I like to handle exachk. Exachk is made available via MOS Doc Id. 1070954.1. The tool is designed to audit various important configuration settings
within an Oracle Database Machine Exadata System - Database Servers, Storage Servers and Infiniband Switches. It verifies key components of the Exadata Database Machine against supported version levels, recommended Oracle RAC settings and Exadata best practices. At the moment we support version 11gR2 for V2 & X2-2.
The tool is non-intrusive, when it completes it's collection and analysis it produces two reports, summary and detailed. If an SR needs to be logged the output can be supplied to Oracle for further analysis . The detailed report will contain Benefit/Impact, Risk and Action/Repair information. In many cases it will also reference publicly available documents with additional information about best practices and how to implement them.
For more and detailed information please see MOS Doc Id. 1070954.1
Blog of Rene Kundersma, Principal Member of Technical Staff at Oracle Development USA. I am designing and evaluating solutions and best practices around database MAA focused on Exadata. This involves HA, backup/recovery, migration and database consolidation and upgrades on Exadata. Opinions are my own and not necessarily those of Oracle Corporation. See http://www.oracle.com/technology/deploy/availability/htdocs/maa.htm.