I understand your point, but I still disagree. Though in fairness, I think we are disagreeing on semantic issues here.

Yes, there certainly are ways to add physical resources to the pool without downtime. There’s all sorts of ways to do it. People have been able to open up IBM mainframes and add RAM to them without turning anything off forever.

My point is that the servers themselves don’t just automatically up their own resource levels in response to anything. If you implement some sort of watchdog functionality, where the servers realize they’re getting too overloaded and ask for more resources, or if there’s some other system watching the servers and deciding how much resources they need, then you can do this sort of thing on-the-fly. Albeit vertically in this scenario. But if such a thing is implemented then that is an architecture unto itself. The concept of “the server” is, at any point, the physical resources that are provided to you. So, the thing I was trying to get across is that it’s pointless to say “this server doesn’t scale”. The server either provides you with the physical resources it says it’s going to, or it doesn’t. If you change the amount of available resources, you can claim that you scaled the server, but the server at that point still doesn’t scale. It just provides an adjusted amount of physical resources.

Thanks for your comment though. It’s good for everybody to be aware of all the facets of this discussion, and I probably didn’t go in depth enough about the points you bring up.

With MS and VMWARE products, you can add resources to virtualized instances on the fly. Some call it “Dynamic Resource Management”, “hot swappable resources”, etc… The main requirement is that the guest OS must support this. I’m only aware of MS products being aware/built for this situation. When the DB needs more ram and cpu, I can add it on the fly, enabling me to have enough time to fix said issue.

“• Dynamic resource management: Windows Server virtualization provides the capability to hot add resources such as CPU, memory, networks and storage to the virtual machines with no downtime. Combined with the hot add features of Windows Server “Longhorn”, this enables administrators to manage their hardware resources without impacting their SLA commitments….” — http://download.microsoft.com/download/3/2/2/32212eab-a431-4cd4-8567-cf951b1322de/Virtualization.doc —

MS beat VMWARE to the punch long ago. :\

VMWARE, at this time, does not allow hot swappable with all pieces of the virtualized hardware. Just network, cpu, and ram. They are ways you can run around the resource scaling of the hard drive (linux-LVM sitting between the physical resources and the hypervisor). I can’t imagine that would be very efficient/powerful.
http://www.malaysiavm.com/images/vsphere/enable_memory_hot_add.png

Honestly, you can never prevent a backend developer from doing multiple query joins from WAN-distributed databases just so you can load the landing page However, you can add resources on the fly when you need to get along.