Re: Oracle RAC Storage Questionnaire/Recommendation

From: Michael McMullen <>
Date: Fri, 19 Feb 2016 14:49:15 +0000
Message-ID: <>

I've been contracting at my current shop for the last four years and everything has been moved to vm apart from a few ODA's.

I've got 4 four node 4 cpu vm racs along with 70+ vm single instance using oracle restart.

The racs are all policy managed which I really enjoy and we make sure that we have one vm rac node per esx host. ie. you don't want all four nodes of a rac cluster to be on one esx host unless they get there via a multiple host failure.

Storage people started out lumping us with everything else but overtime they've had to make some concessions.

Direct path read performance is lousy on the virtual disks for all applications. Some apps it doesn't matter and it's accepted but for those where it wasn't we moved to prdms (physical raw device mappings). You lose flexibility on the vm side with prdms. I think there is some restriction on how many prdms you can have per esx cluster.

All racs are using prdms and you want more smaller disks than one large disk. You could have a diskgroup with 10 100Gb disk for a high i/o app and a diskgroup with one 500Gb disk for less intensive apps.

Now you get the joy of having multiple db/vms being affected by underlying esx host activities/problems.


From: <> on behalf of Sanjay Mishra <> Sent: February 18, 2016 11:19 PM
To: Oracle-l Digest Users
Subject: Oracle RAC Storage Questionnaire/Recommendation

Hi Everyone

Can someone share any template or points that should be taken into consideration for doing planning/Architect of SAN storage w.r.t RAC/ASM infrastructure where we have multiple databases on the cluster. I am giving some points and so likewise need help in creating the list of best practices to plan for new SAN requirement for Oracle infrastructure.

  1. Should we have dedicated SAN for Oracle environment and not shared with any other Application/rdbms or so ? Generally it is not economical for an enterprise to have multiple SAN and so what are the points that need to be considered to carve LUN utilizing Spindles/pool details.
  2. Should we share the Diskgroup among multiple Database like if we have 10 Database on the CLuster or we should isolate some heavy IO/oltp/Warehouse ?
  3. What are best recommendation for the number of Diskgroup? I am not taking into consideration of Sector 4K disk where we might need one extra DG for some Spfile/Voting/OCR etc. Looking what is best practices and why? One reason is that there are some RAC setup where saw one High IO database affect all other application using other database sharing same DG and so if there are multiple such kind of Database then what are best practices?
  4. What are best practices to get LUN carved for ASM ? Ofcourse we will have same size but as I am not good in Storage terms/technology and need advice the best practices to update storage to provide LUNS for different kinds of Diskgroup like Log/FRA/Database etc to avoinf high IO ?

Any other suggestion/advice for Storage is really appreciated


Received on Fri Feb 19 2016 - 15:49:15 CET

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