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Cloud Hosting

Public, Private and Virtual Private Cloud

April 3, 2018

Virtual Private CloudIT has multiple platform options when deciding where best to host applications. But SAP is not just another workload, so in this discussion we will use SAP as our filter. In this installment, we will separate the facts from the hype as we further explore Public, Private and Virtual Private Cloud.

For purposes of this discussion, Virtual Private Cloud (VPC) refers to the Secure-24 Public Cloud platform and is not a generic reference to a Public Hyperscale Cloud solution. But first, some down-to-business talk about Public and Private Cloud.

Value Propositions for Public and Private Cloud

For years, the value propositions for Private Cloud and Public Cloud have been based on cost and elasticity versus performance and security. Much has changed, and it is time to challenge some of these long-held norms.


Let’s start with cost. Yes, Public Cloud compute is still relatively inexpensive. But SAP has data, and data resides in databases, which require RAM lots of storage and/or both. RAM and high-performance storage in Public Cloud are also not as inexpensive as basic compute. So using cost as a reason for Public Cloud does not directly apply in the SAP world.

The other side of cost is the billing model. While consumption-based billing is attractive and makes sense for dynamic workloads, particularly where there are significant spikes in demand that require ever-changing resources, we are  talking about SAP and not web servers, after all. Generally speaking, outside of DevOps and some resource intensive processes that are required for aggregating data, SAP is usually a fairly static environment. The Public Cloud reserved resource billing model proves a stronger case over the Public Cloud consumption-based billing model since it helps you  notice any significant cost savings.  Even then, it fluctuates case by case.


In regards to elasticity, the vast and seemingly, limitless capacity and scalability found in Public Cloud cannot be denied. But again, this is SAP. When is the last time your SAP footprint required massive scaling?


Performance on the other hand is a little tougher to gauge. There are yet to be seen benchmarks that suggest that VM’s with similar resources run dramatically different in Public Cloud.


Last but not least, that leaves security. It’s fair to say that Private Cloud and VPC may not have all of the same risks associated with open platforms and all of the exposure that is associated with public facing IP’s. Having said that, Public Cloud providers continue to devote massive resources to securing their infrastructure at a time when private companies continue to report that their Private Cloud perimeter was penetrated.

So what is the new value proposition for Public and Private Cloud, and more importantly, what platform makes the most sense for hosting SAP?

Demystifying Public and Private Cloud Norms

Fact. Public Cloud SLA’s are lower than Private Cloud and virtual private cloud (VPC). In Public Cloud, you can expect 3(9)’s uptime availability or 99.9% uptime. This is standard regardless of the service provider and this is the standard published uptime SLA. When you do the math, the SLA won’t be missed, and any service credits won’t kick in until a solution has been down for 2.4 hours a day. Based on 30 days in a month, that’s a whopping 72 hours of downtime per month before any penalty.

Furthermore, this SLA only applies when best practices are followed and solutions are deployed over multiple availability zones. This, in effect, doubles all Public Cloud footprints and adds to the infrastructure costs. More concerning, there is no concept of Application Availability SLA in Public Cloud.

Compare this to Private Cloud and to our VPC where the Availability Uptime SLA is 5(9’s) which translates to less than 3 minutes downtime per day, which based on 30 days per month is less than 45 minutes each month. More importantly, Private and VPC also offer an Application Uptime SLA of 4(9’s) or 99.99% availability, which translates to less than 15 minutes downtime per day.

These unique SLA’s are based on two very different approaches in how resiliency and redundancy are delivered. The underlying premise in Public Cloud deployments is that no single server should be viewed as indispensable. Simply put, if a server fails in Public Cloud, the workload should be able to be absorbed elsewhere. If not, a new server can be quickly, almost instantly, deployed. As a result, commodity infrastructure is used when building a Public Cloud.

Instead of having redundancy baked into every component of every server, there are adequate, spare servers and resources to any workloads as needed. In regards to web servers, terminal server farms, multi-master datastores and load balanced applications, the Public Cloud just makes sense. By architecting and deploying over multiple Availability Zones in Auto Scale Groups, the actual risk of a solution failing is further reduced.

In Private Cloud and VPC, resiliency is also baked into the infrastructure. Instead of commodity infrastructure, infrastructure that has redundant components is deployed. As a result, many platform failures and hiccups can be outright averted. Given that SAP is not just another workload, and given that SAP can be sensitive to platform variations, Private Cloud and VPC are viewed as good hosting options, as well.

Choosing a Platform for Hosting SAP

So which platform makes the most sense for hosting SAP? That actually depends more on you, your preferences and your biases. We have developed a unique SAP, purposely built Private Cloud and VPC platforms worthy of your consideration, but we have customers that are very satisfied on all three platforms and pride ourselves in being platform agnostic.

Even though the costs are surprisingly similar, there are special considerations, pros and cons to navigate for each platform. At the end of the day, the most important aspect of any SAP deployment is not the platform, but how the solution is architected, how the solution is monitored, and how the solution is cared for.

It starts with architecting for the underlying platform. In Public Cloud, this translates to architecting over multiple Availability Zones and Auto Scale groups. Keep in mind that resiliency and availability in Public Cloud is engineered into the architecture. As a result, the lower SLA’s in Public Cloud do not accurately represent the uptime you should expect.

The reality is that Hypervisors need to be patched and maintained, and VM’s are bounced around based on resource constraints. This makes the very nature of Public Cloud more fluid than Private Cloud or VPC, but nothing to fear.

In contrast, in Private Cloud and VPC, best practices generally call for architecting in clusters and distributing and load balancing workloads. As a result, Private Cloud and VPC are extremely stable and resilient. For some, this makes for an easy transition from self-hosted and on-premises solutions.

Monitoring is central in every SAP deployment, regardless of the platform. The objective is to keep SAP running, allowing time-sensitive processes to complete. In Public Cloud, monitoring traditionally triggers automation. This is effective when routing around bottlenecks and spinning up new services as necessary.

While this automation is extremely powerful, SAP can be needy and does not always respond well to being bounced between hosts or even between guests. For that reason, we also leverage monitoring to identify bottlenecks before potential issues become service impacting. For anyone that has ever experienced a hung month end process that risked closing out in time, it is clear that this proactive approach is as important in Public Cloud as it is in Private Cloud or VPC.

Final Thoughts on Virtual Private Cloud

Finally, SAP takes significant care and feeding. Regardless of the platform, maintaining SAP is a bit of an art form. This can be a constant balancing act that requires a well-maintained platform, a hardened OS, a tuned database, and a properly configured application. When SAP is properly maintained and continuously tuned, it tends to run smoother and with less interruptions.

In the next installment, we will discuss the importance of developing a Cloud strategy as we start to examine the moving parts that will likely influence your business case for a migration to the Cloud. Talk to us to learn more on Public, Private, and Virtual Private Cloud platforms today.