Luca Canali and ASM Metadata Internals

My experience, findings and thoughts in my daily work with Oracle products

Published Wednesday, June 14, 2006 by Radoslav Rusinov | E-mail this post

In a recent technical paper Luca Canali explains how to find the mapping between physical storage, ASM allocation units, and database files by querying the undocumented X$ tables.
By using the information retrieved from X$KFFXP table he succeeded to:

Retrieve a file directly from ASM disks
Monitor how the extents in a datafile are allocated across ASM disks
Monitor how a datafile is spread across ASM disks due rebalancing operations

Here you can find the full version of the document: A peek Inside Oracle ASM Metadata

Luca Canali is working in the IT Department of CERN - European Organization for Nuclear Research Geneva, Switzerland.
Under HAandPerf section of the PSS Group you can find more very interesting white papers and presentations authored by Luca. Links to some of them:

I/O measurements with Orion - I/O performance measurements using Oracle's ORION testing tool
I/O Performance Measurements with RAC - Oracle 10g RAC and ASM on Linux - storage performance measured with Oracle's SQL
Experience with RAC/Linux on no-brand hardware
ASM-based storage to scale out the Database Services for Physics
Oracle 10gR2 configuration

Luca Canali is the author of SQLPython - a command line tool written in python that emulates Oracle's SQL*Plus basic functionalities.

Another interesting link with lot of technical information:
DBA Area of the Physics Database Services Support Group

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About me

» I'm Radoslav Rusinov
» From Sofia, Bulgaria
» Employer TechnoLogica Ltd.
» I am working as a Database Consultant in Sofia, Bulgaria. My main professional interests are in the database area and especially in the Oracle RDBMS, including database design, development, security and administration.
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