Exadata and OVM

Exadata and OVM.

OVM and Exadata.

It’s not been the best-kept secret in the world, but it is now a reality with Oracle’s new X5 engineered systems.

I don’t like it either, though I admit that I might just be a purist snob. As far as I can see, this might be useful in two possible scenarios:

1) Saving on additional cost option licensing.
Picture this: you have four databases on your Exadata machine and only one of them needs the {INSERT EXPENSIVE COST OPTION HERE} option.

Instead of buying, for instance, an Advanced Security license for all 144 cores, you might consider dividing up your X5-2 half-rack into four virtual machines – one for each database – and only license Advanced Security for the virtual machine on which that particular database resides.

Assuming each virtual machine is provisioned identically (with 36 cores each instead of the full 144), the cost of licensing ASO is 25% of what it was if you had licensed the entire machine.

Some of those cost options are expensive, definitely. But why not consider a smaller, dedicated Exadata machine for that database instead? Why not consider an alternative instead, such as ODA?

2) Capacity on-demand licensing.
Let’s say that you KNOW you’re going to migrate more databases onto your Exadata machine in the future, but you’re not using its full capabilities to support the databases that are running there right now. Bear with me for argument’s sake…

With OVM, you’re able to license a minimum of 40% of the cores on your Exadata system. If you’re not getting close to fifth gear right now, but you know you will be at some point, you could use OVM to license in a “capacity on-demand” fashion and crank things up as your needs increase.

Of course, given the exponential improvements that come with each new version of Exadata, wouldn’t you try your best to wait until a couple of months before you DID need the extra horsepower so you could buy the latest and greatest Exadata then?

Let’s say you DO eventually get to 100% usage, you still have that extra virtualization layer in the stack and whatever issues go with it, including having to maintain it. To remove it, one assumes that the machine would need to be rebuilt, which isn’t a particularly attractive option.

“Exadata is expensive”
I understand the “Exadata is expensive” argument, but I don’t really think this helps with that very much – you’re still laying down a big wad of cash when you buy the hardware, no matter how you slice the licensing up. Is it really going to be worth the hassle of that extra virtualization layer to save (and possibly only temporarily) on licenses?

Oddly, I think the new elastic configuration capability in X5 makes the argument harder to make: you could achieve the same thing by choosing a different hardware configuration and/or adding comp nodes or storage cells as your needs dictate.

I’m sure there’s a compelling reason out there for putting OVM on Exadata that I haven’t figured out yet, there usually is. Until then, I’m back to scratching my head…

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5 thoughts on “Exadata and OVM

  1. Martin M says:

    OVM is most likely primarily used for isolation.

    Liked by 1 person

  2. Peter Hand says:

    Mark, I am with you, a snob and a purist. The Oracle database has been developed for multi-tenancy and does it well. It has _for years_. Isolation? I think the limiting factor is still the hardware layer. But ok, maybe regulatory compliance. A separate Oracle home and independent resources usually does the trick for me. Having said that, I am an Oracle Exadata Sales Consultant, so I encourage customers to create their virtualized database architectures with great care, whether they are on Engineered Systems or not. Know what you’re getting, know what you’re giving up and know how to keep the balance.

    Liked by 1 person

  3. robinsc says:

    I’m with Peter on this one

    Liked by 1 person

  4. Efstathios Efstathiou says:

    “Welcome to the Exadata Oracle VM Beta Testing Program”… that’s how it feels atm. running an Exadata X-5, that was originally purchased with Oracle’s promise to properly do VLAN-Tagging (acutally you can’t configure it in the OEDA) tool. Next ptifall is, that connecting your ZFS appliance or Media Server via Infiniband is only supported on Bare Metal. Those two things should be considered, when evaluating the usage of OVM. In most cases for sizings like an Eigth Rack or Quarter Rack, you might be better off cost wise with one or two ODA X-5 systemes or generic x86 iron plus NVMe drives plus FlashGrid, especially if you are running mainly OLTP workloads, since all the offloading magic is designed mainly for DWH. If you want a truly working Exadata, I personally would recommend at least adding 3rd database Server and IB-switch, so we can have a failure of a database server, switch and storage cell and still be redundant. Then we can call this an enterprise solution. Stay away from entry level solutions with only 2 db servers and OVM on top, as the stack is still new, adds alot of layers and further increases complexity of management (Dom0, Grid Disk partitioning, VM-Cluster, Grid Infrastructure Cluster) and limitations.


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