Re: Oracle RAC on VMWare

Hi Amir

We have run RAC on VMWare platforms ( a couple of different versions). My view is that by and large implementing RAC on top of VMWare is usually done for the wrong reasons (to migrate workloads as is and to consolidate workloads). There are a few reasons why you might wish to run RAC.

• You have built RAC aware applications that can already respond appropriately to ONS events via TAF, Application Continuity etc.
• You have a strictly low downtime tolerance in the event of failures - as in downtime can be no longer than x seconds, not as in N 9s.
• You already run rolling upgrades/patching and don't want to lose that ability or switch to standby first upgrades/patching
• Your workload is already larger than the largest physical machine you have can cope with.

• You'll need to allocate thick provisioned multi-writer disks for the database storage - this means that some VMWare features aren't available to you.
• You should ensure that you apply anti-affinity policies to make sure the RAC nodes don't all end up on the same physical hardware!
• You'll need a specific private network(s) for your RAC clusters.
• You may well have added licensing headaches to deal with.
• VMWare admins are often big fans of overallocating CPU and Memory - this tends to work very, very badly indeed with performance-sensitive database workloads.
• RAC clusters often have high-performance SAN storage dedicated to them. Virtualized databases tend to have shared (often lower performance) storage. If your database application is extremely I/O demanding then a VMWare platform may struggle. VMWare can help with identifying this.

On Thu, Aug 6, 2020 at 2:08 AM Hameed, Amir <Amir.Hameed_at_xerox.com> wrote:

> Hi,
>
> Our data center is in the process of doing hardware refresh and their
> priority is to move every physical server to VMWare VM. Currently, we
> primarily run middleware and some single instance databases on VMWare but
> all databased that are RAC’d are configured on physical servers. I believe
> that Oracle didn’t certify RAC on VMWare until recently. I am reaching out
> to this DL to find out:
>
> 1. Are there folks on this DL running Oracle RAC on VMWare and what
> has been their experience?
>
> 2. Are there any caveats of running Oracle RAC on VMWare?
>
>
>
> Any feedback will be greatly appreciated.
>
>
>
> Thank you,
> Amir
>
>
>

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Niall Litchfield
Oracle DBA
http://www.orawin.info

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