On 3/12/2018 3:22 AM, Deepak Goel wrote:
A single OS and JVM does not scale linearly for higher loads. If you have
seperate OS and Java, the load is distributed across multiple instances
(with each instance only requiered to support a smaller load and hence
would scale nicely)

I had found this for running multiple apache servers on multiple VMs as
compared to a single instance (not Solr). But i am pretty sure it would be
same for Solr too

I think this is the last thing I'm going to say on the subject.  You disagree with a fundamental hardware concept that I've learned through experience, so I might never convince you of anything.  If that's the case, I'm done trying after this, and I wish you the best of luck with your efforts.

If the physical hosts you put the VMs on are far more powerful than you would ever use for bare metal, and/or you split virtual machines between different physical hosts, then that installation might scale better than a single bare metal host. The decision makers in most companies are usually a lot more willing to buy really expensive hardware if you tell them it's for virtualization than they are for a single-purpose machine.

But if the bare metal environment has the same number of physical servers with the same specifications, then a well-tuned bare metal setup is going to perform better than virtual machines.  There's nothing wrong with VMs.  They can perform very well if everything's sized appropriately.

Anytime a virtualized environment performs better than bare metal, it's usually going to be that way because the virtualized environment has different hardware than the bare metal environment.  That hardware will probably be much more expensive, and/or newer hardware that just works better.  It might also happen because the software installation was not set up correctly to fully utilize all the hardware.

Solr works best with a lot more memory installed than people usually install, *especially* with virtual machines, where RAM may be an even more precious commodity than it is in bare metal servers.


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