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timcoote
Contributor
Contributor

Does it always make sense to virtualize Oracle?

Hullo

I can see value in virtualizing small Oracle instances. However, unlike SQL Server, Oracle's architecture and commercial terms favour large, single instance installs, and I can see some challenges with larger scale virtualization:

  • you've got to track all Oracle instances in the estate under the terms of the licence agreement

  • I think that the licensing terms mean that every Oracle instance on an ESX server would incur licensing and support costs for every physical CPU on the server.

  • cache cannot be shared between Oracle instances

  • There's a higher admin cost of multiple Oracle installs.

  • RAC's scaling and failover capabilities are tailored to the DBMS' needs and ought to be more effective

  • Production Oracle installs actually span multiple machines, which need to be treated as a single entity - I don't think that virtualisation is much worse than native install here, unless someone accidentally moves one of the VMs with that whizzy GUI.

I guess that the maximum VM size is quite small for a large DB, too. Conversely, overall Oracle performance may be better in a virtualised environment, rather than consolidated if the DBMS performance is non-linear.

Has anyone done any analysis of whether it is always worth virtualising Oracle? Is there a cutover point? Is it beyond the size of the largest organisation ?

Tim

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mikepodoherty
Expert
Expert

Does it always make sense to virtualize Oracle? No

IS there a cutover point? That depends and it depends on more than just the size of the database instance(s). What is the database being used for? Is it disk intensive? What type of storage do you haveto support the instance(s)? What are your reliability, failover, performance requirements? What is the interface being used to access the database? How well is the code written for the interface application? Are the querires beign run in the most efficient location?

RAC has a lot of advantages - but DRS/HA also provide acceptable continuity in a local environment. RAC has distance and configuration limitations and you may need DataStream. VMware has site recovery manger - each provides good value depending on how you've developed your implementation strategy and your system architecture.

I know there are multiple other considerations you need to incorporate in determining whether it makes sense to virtualize Oracle (such as licensing.) I've listed the above to point out that there is no simple cut and dried formula.