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How oracle reads data from OCR with out mounting disks?

Questions relating to Oracle Real Application Clusters (RAC) and Clusterware.

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How oracle reads data from OCR with out mounting disks?

Postby gssr141 » Wed May 28, 2014 11:25 am


Just now I restarted My cluster , I have one doubt,

1).OCR files stores in ASM disks, but asm disks are mounted by ASM instanceonly, to start all resources on cluster Oracle need to read the OCR data from ASM disks, but ASM instance in not yet started how oracle reads the data from ASM disks?

2).to startup a asm instance we need spfile, assume that my asm instance is down and not yet started ,and in the dbs location there is no spfile.

Now I try start the asm instance , I was shocked ::: asm instance started , and i check that asm spfile is stored in asmdiskgroup.

My doubt is how oracle read the data from asmspfile to startup asm instance without mounting asmdiskgroups?
If asm instance started then only diskgroups will mount ..and then only we can read the data from asmdisks. right?

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Re: How oracle reads data from OCR with out mounting disks?

Postby Tim... » Wed May 28, 2014 12:56 pm


If you check out the docs you will see that OCR, voting discs and spfiles are stored in such a way that they are readable without the asm instance being on.


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