{"id":1473,"date":"2012-05-29T00:00:00","date_gmt":"2012-05-29T00:00:00","guid":{"rendered":"https:\/\/test.simple-talk.com\/uncategorized\/a-private-cloud-that-isnt-really-a-cloud-at-all\/"},"modified":"2024-07-15T20:15:34","modified_gmt":"2024-07-15T20:15:34","slug":"a-private-cloud-that-isnt-really-a-cloud-at-all","status":"publish","type":"post","link":"https:\/\/www.red-gate.com\/simple-talk\/cloud\/infrastructure-as-a-service\/a-private-cloud-that-isnt-really-a-cloud-at-all\/","title":{"rendered":"A private cloud that isn't really a cloud at all"},"content":{"rendered":"
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What I’ve been finding over the past nine months since we virtualized our physical infrastructure and moved it to Rackspace’s private cloud solution<\/a>, is that we’re not really getting a lot of the benefits that you think of from the cloud.\u00a0 Our private cloud is essentially a hosted virtual environment.\u00a0 Virtualization by itself brings some real benefits, and it’s clearly a step on the continuum towards cloud computing but it feels like a smaller step than I expected.<\/p>\n

I’ve spent a lot of hours on support calls, monitoring, troubleshooting, and otherwise managing our private cloud environment.\u00a0 Other than the fact that our servers are virtual, those activities are indistinguishable from the types of activities we were engaged in with our traditional hosted physical infrastructure.\u00a0 This got me thinking about what a private cloud is and what my expectations should be.<\/p>\n

Cloud Profiling<\/h2>\n

There’s no shortage of variants and nuanced definitions of what a cloud is, but there are some familiar themes.\u00a0 The simplest definition: the dynamic provisioning of IT capabilities (hardware, software, or services) from third parties over a network<\/a> , while simple, it isn’t really descriptive enough to evaluate our private cloud against.\u00a0 Instead I’ll use the, perhaps imperfect, five defining characteristics described within The NIST Definition of Cloud Computing<\/a>.<\/p>\n

Does our private cloud demonstrate these characteristics?<\/p>\n

1.\u00a0 On-Demand self-service – <\/strong>With our private cloud we only have on-demand self-service in a very limited sense.\u00a0 We can allocate and de-allocate resources for a VM (CPU, Memory, and disk) via the portal.\u00a0 We can create additional VM’s and even clone existing ones via the portal, but network configuration, adding VM’s to the load balancer, joining the new VM with cluster software, and other application configurations will need to be done manually. In all cases we’re only playing with a finite set of resources.<\/p>\n

2.\u00a0 Broad network access – <\/strong>We can access the private cloud portal via the web and mobile devices, so we pass in that regard.<\/p>\n

3.\u00a0 Resource pooling – <\/strong>With our private cloud, resource pooling is extremely limited.\u00a0 Our resources are only pooled within our physical infrastructure, in one datacenter.\u00a0 VMs may move based on resource demand from one physical host to another dynamically using vMotion<\/a>, but they don’t go very far and the pool isn’t very big.<\/p>\n

4.\u00a0 Rapid elasticity – <\/strong>Our private cloud elasticity is limited to the resources available on our physical hosts, and while CPU and memory can be reallocated to existing VM’s fairly rapidly, we cannot quickly add additional VMs, nor would there necessarily be great advantage in doing so because they’d only be competing for the same underlying physical resources.<\/p>\n

5.\u00a0 Measured service – <\/strong>A private cloud certainly isn’t pay as you go; we don’t get credit for un-used CPU and memory.\u00a0 We do get a measure of optimization of resource usage across physical hosts with vMotion<\/a>.\u00a0 But it’s up to us to make sure resource utilization is optimized.\u00a0 We can under-allocate resources leaving infrastructure idle so that we have the capacity to scale up at peak, or we can over-allocate to make sure we’re maximizing our infrastructure but then have no wiggle room to burst.\u00a0 Sound familiar?<\/p>\n

According to these defining characteristics it doesn’t sound like a private cloud is actually a cloud, at least ours doesn’t.<\/p>\n

The things I’ve seen<\/h2>\n

Rather than split hairs over definitions of cloud terms, I’ll enumerate some of my experiences with our private cloud.<\/p>\n