SAPonPower

An ongoing discussion about SAP infrastructure

Is your company ready to put S/4HANA into the cloud? – Part 2

And now, the details and rationale behind the questions posed in Part 1.

  • What is the expected memory size for the HANA DB? Your HANA instances may fit comfortably within the provider’s offerings, or may force a bare-metal option, or may not be offered at all.  Equally important is expected growth as you may start within one tier and end in another or may be unable to fit in a provider’s cloud environment.
  • What are your performance objectives and how will they be measured/enforced? This may not be that important for some non-production environments, but production is used to run part, or all, of a company.  The last thing you want is to find out that transaction performance is not measured or for which no enforcement for missing an objective exists.  Even worse, what happens if these are measured, but only up to the edge of the provider’s cloud, not inclusive of WAN latency?  Sub-second response time is usually required, but if the WAN adds .5 seconds, your end users may not find this acceptable.  How about if the WAN latency varies?  The only thing worse than poor performance is unpredictable performance.
    • Who is responsible for addressing any performance issues? No one wants finger pointing so is the cloud provider willing to be responsible for end-user performance including WAN latency and at what cost?
    • Is bare-metal required or if shared, how much overhead, how much over-commitment? One of the ways that some cloud providers offer a competitive price is using shared infrastructure, virtualized with VMware or PowerVM for example.  Each of these have different limits and overhead with VMware noted by SAP as having a minimum of 12% overhead and PowerVM with 0% as the benchmarks were run under PowerVM to start with.  Likewise, VMware environments are limited to 4TB per instance and often multiple different instances may not run on shared infrastructure based on a very difficult to understand set of rules from SAP.  PowerVM has no such limits or rules and allows up to 8 concurrent production instances, each up to 16TB for S/4 or SoH up to the physical limits of the system.  If the cloud provider is offering a shared environment, are they running under SAP’s definition of “supported” or are they taking the chance and running “unsupported”?  Lastly, if it is a shared environment, is it possible that your performance or security may suffer because of another client’s use of that shared infrastructure?
  • What availability is required? 99.8%? 9%?  99.95%? 4 nines or higher?  Not all cloud providers can address the higher limits, so you should be clear about what your business requires.
  • Is HA mandatory? HA is usually an option, at a higher price.  The type of HA you desire may, or may not, be offered by each cloud provider.  Testing of that HA solution periodically may, or may not be offered so if you need or expect this, make sure you ask about it.
    • For HA, what are the RPO, RTO and RTP time limits? Not all HA solutions are created equal.  How much data loss is acceptable to your business and how quickly must you be able to get back up and running after a failure?  RTP is a term that you may not have heard to often and refers to “Return to Processing”, i.e. it is not enough to get the system back to a point of full data integrity and ready to work, but the system must be at a point that the business expects with a clear understanding of what transactions have or have not been committed.  Imagine a situation where a customer places an order or paid a bill, but it gets lost or where you paid a supplier and mistakenly pay them a second time.
  • Is DR mandatory and what are the RTP, RTO and RTP time limits? Same rationale for these questions as for HA, once again DR, when available, always offered at an additional charge and highly dependent on the type of replication used, with disk based replication usually less expensive than HANA System Replication but with a longer RTO/RTP.
    • Incremental costs for DR replication bandwidth? Often overlooked is the network costs for replicating data from the primary site to the DR site, but clearly a line item that should not be overlooked.  Some customers may decide to use two different cloud providers for primary and DR in which case not only may pricing for each be different but WAN capacity may be even more critical and pricey.
    • Disaster readiness assessment, mock drills or full, periodic data center flips? Having a DR site available is wonderful provided when you actually need it, everything works correctly.  As this is an entire discussion unto itself, let it be said that every business recovery expert will tell you to plan and test thoroughly.  Make sure you discuss this with a potential cloud provider and have the price to support whatever you require included in their bid.

 

I said this would be a two part post, but there is simply too much to include in only 2 parts, so the parts will go on until I address all of the questions and issues.

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May 4, 2017 Posted by | Uncategorized | , , , , , , , | Leave a comment