Oracle Direct NFS

Features embedded in Oracle Kernel Improves performance and manageability for NFS drives Configuring: NFS file system should be mounted and available. Direct NFS does not mount drives Direct NFS client uses either: configuration file called ‘oranfstab’ mount file tab – /etc/mtab First: $ ORACLE_HOME/ dbs/oranfstab which would specify the Direct NFS Client settings for a single database. Then /etc/oranfstab …

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Oracle ASM

A brief discussion on Oracle ASM and some of its advantages over other file systems.     Notes: Database centric file system only used for managing database files High performance Requires a certain amount of tuning Not suitable for all applications Current recommendation is to allow ASM handle raid mirroring rather than let hardware handle it Probably …

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Manually upgrading to 11g

You can directly upgrade an Oracle database from version 9.2.0.4 or higher, directly to 11g Upgrade Process. Open database in Upgrade mode:      startup upgrade Pre-Upgrade information tool:      utlu111i.sql Precursor to the upgrade. Generated report on required  and recommended changes to make.. Generally increasing tablespace sizes or remove parameters. Upgrade script:   …

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Some notes on Oracle Indexes

Oracle Indexes The degree to which indexes help performance depends partly on the selectivity of the data.High selectivity – Few rows match the index valueLow selectivity – like Country name returns many rows from the index If data is selective but the rows are not stored near each other in the table, many blocks may …

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What is Oracle Exadata

Notes: Data appliance Server with preinstalled and pre optimised database Hardware designed to work with the database software specifically Pre configured clustered database server Exalogic is a preconfigured clustered application server Exadata is a pre configured clustered database server There are other products but they are targeted at OLAP specifically (read rather than write) Exadata supports OLTP and OLAP The first …

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Exadata Smart Scan

This is a pretty cheesy presentation but it gets some interesting points about exadata and smart scan over in only 3 minutes. Notes: Exadata offloads work to its storage servers which reduces the data that needs to travel over the network to the database servers. For example, the storage servers filter out rows that are …

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Perspectives on Exadata

This is a great discussion on and around Oracle Exadata by 2 performance tuning experts.     Notes: A very relaxed presentation on the ins and outs of Exadata from a performance tuning and optimization perspective.Skip to about 10 mins in to get past the introductions.Exadata isn’t a solution to all performance problems. You can …

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How to remove old RMAN backup files.

It is possible to use operating system commands such as rm on linux to delete RMAN backup files and generally recover from it, however you are far better using built in RMAN commands to do this. $ rman target / NOCATALOG First, check that all backup files are still available. This will show whether files …

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