Unlocking: How the ASM instance starts with SPFILE stored in your own ASM Diskgroup

This a good article written by Aychin Gasimov, gives us a clear understanding about how the ASM instance starts with SPFILE stored in your own ASM Diskgroup.

Oracle 11gR2 have many new futures in Grid Computing area. One of them is Oracle Local Repository (OLR), this repository designed to store information and profiles for local resources, resources that dedicated to particular node. It improves the performance of accessing local resources profile information, redundancy and manageability. In Grid Infrastructure RAC configuration there is usual one global shared OCR and OLR’s on each node. In Oracle Restart environment there is only OLR repository. In 11g R2 there is also new feature, Grid Plug and Play (GPNP), as the name implies, it helps to automate and simplify some of the aspects of grid administration. GPNP maintains profile, it is XML file that stores the configuration information of some components maintained by GPNP, for example vips and interconnect information is stored here.

But in this post, I wont to discuss another new feature of 11g R2, it is the possibility to store the server parameter file (spfile) on the ASM disks, also for ASM instance itself! And there is some reasonable questions arise:

  1. How process can read the spfile from ASM disks, if they are not mounted yet
  2. How process knows where to get spfile if there is no init.ora file in $ORACLE_HOME/dbs with spfile=[path to spfile] parameter
  3. What about asm_diskstring parameter?

Third point is important for ASM instance because, before reading spfile from ASM disks, we need to identify them, to identify them we need spfile to get asm_diskstring parameter!

Click Link Below..

http://aychin.wordpress.com/2011/01/22/oracle-11gr2-asm-spfile-eng/

Enjoy

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