11gR2 – ASM redundancy levels.

 

In 11gR2 ASM diskgroups are used 1) by Grid infrastructure for the OCR, Voting disk and the ASMspfile. 2) by the database for DATA and FRA.

ASM redundancy levels, can be a bit misleading in Oracle 11gR2 compared to 10gR2.   They are called the same, Normal redundancy, High Redundancy and External Redundancy.  However, depending on what area of the 11gR2 configuration this will be used, the number of disks required to configure are not the same.  DBA’s seldom are able to take the difference into consideration when requesting disks /LUN’s from the storage administrators and are taken by surprise during installation.

Grid Infrastructure:  When configuring diskgroups for the OCR file, voting disk and ASMspfile, Normal redundancy requires 3 disks/LUNS to be part of the diskgroup.  High redundancy requires 5 disks/LUNS to be part of the diskgroup.  External redundancy requires just one disk/LUN to be part of the diskgroup. The below screen output shows the error message when only one disk/LUN is selected for the GRID diskgroup.

 grid7

Database: When configuring diskgroups for DATA and FRA, normal redundancy requires 2 disks/LUNS to be part of the diskgroup.  High redundancy requires 3 disks/LUNs or failure groups to be part of the diskgroup.  External redundancy requires just one disk/LUNs or failure groups to be part of the diskgroup

asmca2

More about configuring OCR and voting disks in the next post.

About Murali Vallath
Murali Vallath has over 20 years of experience designing and developing databases. He provides independent Oracle consulting services focusing on designing and performance tuning of Oracle databases through Summersky Enterprises (www.summersky.biz). Vallath has successfully completed over 100 successful small, medium and terabyte sized RAC implementations (Oracle 9i, Oracle 10g & Oracle 11gR2 ) for reputed corporate firms. Vallath is a regular speaker at industry conferences and user groups, including the Oracle Open World, UKOUG and IOUG on RAC and Oracle RDBMS performance tuning topics. Vallath's Publications: Author: 1. ‘Oracle Real Application Clusters’ Publisher: Digital Press 2. ‘Oracle 10g RAC, Grid, Services & Clustering’ Publisher: Digital Press. Co-Author 3. 'Automatic Storage Management Publisher: Oracle Press'

3 Responses to 11gR2 – ASM redundancy levels.

  1. Pingback: 11gR2 – OCR /Voting Disk Redundancy…. POC – Method I « Summersky RAC Notebook

  2. Is it possible to get Oracle linux and Oracle desktop DB and configure RAC ? This is for learning. Are all these free for limited use ?

    Something like this blog( http://jaffardba.blogspot.com/2007/01/desktop-rac-virtually-installed-and.html) mentions.

    Mohan

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