I am confused about voting disks, OCR and other diskgroups. Basically I want a DATA diskgroup for datafiles and an FRA diskgroup for backups and archivelogs. These will each have 4 LUNS associated of 100GB each for DATA and 25GB each for FRA, totalling 400GB and 100GB respectively. Both will have external redundancy.
I also need to configure the voting disks and the OCR (I have set aside 4 x 1GB disks for these), but I am not sure at what point I do this. I am being asked to create a diskgroup during the grid installation, so I have called this diskgroup 'OCRVOTING' but do I add all 4 disks to it? How will I tell Oracle which of these disks are voting disks and which is for the OCR, or do I have this totally wrong?
Further, if it is OK to have only a DATA diskgroup that acts as datafile storage, OCR and voting, why do people use a separate diskgroup for OCR and voting? Also, is the OCR generally stored on the same disk(s) that is/are used for the voting disk(s), or is there a separate disk for the OCR usually?
Putting the OCR and voting disks on the same disk group as your databases may limit or complicate your options in the future. For instance, if at some point you would want to rebuild or change parameters in the DATA group, you should not have to worry if the ASM can handle that properly.