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In my organisation we have plenty of mission critical servers and currently there is a debate whether for critical servers we should use VMWare vSphere 5 or have a dedicated hardware?

The perception from senior management and the developers, some applications (oracle DB / Glashfish / etc..) might not be compatible with vmware because it does not directly interacts with the hardware layer, instead they OS interfaces with the vmware layer (compatibility wise). There is also a argument that the resources are shared among the vmware hosts (performance wise).

My approach is less sceptic and I'm of the opinion that if you assign the necessary resources, the OS will perform regardless dedicated server or VmWare. I also believe that VmWare is the "virtualization standard" (personal opinion), meaning they're compatibility must be quite extensive.

For the sake of discussion, We can pickup the worst case scenario.. 20 TB Oracle Database 11G with 6,000 IOps. How reliable is it running it with VmWare vs Dedicated hardware (server blades)?

Thanks,

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  • Also if you need dedicated hardware for performance there is a feature called SR-IOV. Very cool! Virtualization is the way to go IMHO.
    – hookenz
    Dec 2, 2013 at 21:21

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Well, you ahve the typical management and developers - clueless. Sorry to say.

some applications (oracle DB / Glashfish / etc..) might not be compatible with vmware b

THey work fine. NOTHING these days directly talks to the hardware. Oracle? What you install that on? Hint - that what you install it on talks to the hardware.

There are good reasons not to virtualize Oracle, but that is mostly around "large databases run on clusters, not a (small) vm", and not "oh, it talks to the hardware.

There is also a argument that the resources are shared among the VMware hosts (performance wise)

Makes sense. If you need those resources. Not everything needs them - then virtualization allows multiple vm's on a larger server. Main problem these days is that servers don't come that small anymore.... so putting hardware there for a dedicated DHCP/DNS machine is wasteful.

My approach is less septic and I'm of the opinion that if you assign the necessary resources, the OS will perform regardless dedicated server or VMware.

And that is something that Virtualization specialists have said for years.

20 TB Oracle Database 11G with 6,000 IOps. How reliable is it running it with VmWare vs Dedicated hardware (server blades)?

You mean a small low power database? Seriously? Something that a tablet can run? Or a laptop? 6000 IOPS is about 10% of what a SSD does, btw.

Try that:

  • SQL Server
  • Around 800GB
  • RUnning in a VM with 48gb memory.

Basically that is a small setup. And it works like a charm. It is the only VM on that server, though.

That basically is it. Reliability is identical - the machine crashes it crashes. It all is about putting enough ressources in. Not everything makes sense to virtualize - for example f you ever get into reaqlly large databases you may want to look at oracle ExaData hardware and that is non-virtualizable.

But otherwise, the arguments I hear so far indicate cluelessness.

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You're mixing up a lot of terms here.

The reliability of a VM solution is the product of the reliability of the physical host and the virtualization software. So in theory it's a bit lower, but in practice that's pretty much neglegible.

Compatibility maybe was an issue a decade ago, but it's 2013 and virtualization solutions are mature. There's pretty much no application that cannot run in a virtual machine.

Performance is where the big difference is. Virtualization adds overhead, and sharing resources can lead to bad performance. But you're on the right track there: assign the necessary resources. Most complaints from people about VM performance are the result of underprovisioning, which would be the same if you buy hardware that's too slow.

The only way to make sure whether virtualization would make sense for you is to make sure there's a benefit in it for you and to test whether there are no performance downsides.

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I can think of very few arguments for running directly on dedicated hardware these days. Virtualization solutions are very mature, very stable, and offer great return on value.

In my opinion the benefits gained from virtualization are so valuable that they easily offset any performance loss from not running directly on bare metal. (Also keep in mind that with the proper hardware architecture, most performance concerns can be addressed.)

Some examples (from the Vmware side) of virtualization that improve reliability are: vMotion, HA, and Fault Tolerance.

  • vMotion allows you to move powered-on VMs to new ESXi hosts without powering off the VM. Used for load-balancing hosts or moving VMs off for maintenance on underlying hardware.

  • HA (high availability) monitors if a VM is up or not, and powers the VM back on (on a new host if needed). Used for important but NOT mission-critical servers.

  • Fault Tolerance uses vLockstep to keep a secondary VM 100% in sync with a primary copy of the VM. If something happens to the primary, the secondary kicks in immediately.

Of course, you can't also forget that virtualization allows you to perform back up and restore operations at the server level, which alone makes it worth using.

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