I am preparing a 2 nodes RAC with Oracle 12c for evaluation purpose and I am looking for some advise on how I should prepare the storage.
I have a storage array with 16 disks of 600GB each.
My requirements are
- follow best-practices (up to a point, not if it is too costly)
- ease of management is more important than to get the last bit of performance.
The more I read documentations, forums, blogs the more confused I become about how I should create my ASM disk groups.
I have two scenarios in mind. I did implement the first one in my evaluation but then I realized that it might not fulfill the best-practice requirement.
1. create two luns at the SAN, each LUN with 8 disks in RAID0 10. Then create two asm disk groups: +DATA and +FRA. Then put the voting files on +DATA, put the OCR files on both disk groups, the db on +DATA and the fra on +FRA. It all seemed logical and easy to do. But then I start to find contractictory information that Oracle recommends to have 3 voting files and have them on separate disks.
2. I have a red-had "Best-practice" white paper (deploying Oracle 11g on RAC). In their reference architecture they create much more LUN's at the storage level, specially they create 3 LUN's dedicated to the voting files. Each of those 3 LUNs contains two disks in mirror. From the 3 LUNS they then create 1 asm disk group in normal redundancy. But this seems to me a huge waste of space in my case, because I would lose 6 of my disks to do that set-up. I could do the same without the external redundancy so losing only 3 disks (no external redundancy, only the ASM redundancy). But it is still a big waste of space considering that will be allocating 3x600G while the voting file is only 1G in size !!
Can someone advise if scenario 1 is acceptable or not ? I can't really understanding what is the point of mirroring the voting files like crazy, because if I loose my +DATA disk group i lose my RAC anyway, not ? Or maybe there is another alternative that I did not realize ?
Also I was reading something strange in the recommandation section of the ASM admin guide: they say, "The number of LUNs (Oracle ASM disks) for each disk group should be at least equal to four times the number of active I/O paths. For example, if a disk group has two active I/O paths, then minimum of eight LUNs should be used. The LUNs should be of equal size and performance for each disk group."
Does this means I should not ask the storage admin to create 2 big LUN with 8 disks each but instead ask him to create 8 LUN (8 times 2 disks) ? It seems that it would add quite some management overhead to me ?
I hope that someone can advise on which way I should follow or point me to a good documentation/discussion
Thanks and regards, Pierre