HCI

Hyperconvergence in campus IT-Why taking a software approach is best


Perhaps the most important lesson to come from analyzing data center HCI refreshes and upgrades is that not all HCI solutions are created equal.

Success through Flexibility

One lesson learned is that HCI solutions can be quite inflexible.  Offerings from multiple vendors–including industry-leading nameplate vendors–have proven to be uncomfortably restrictive. The dominant example of this is restrictions on the use of dissimilar nodes within a cluster; the balance between storage capacity, storage performance, CPU capabilities and amount of RAM isn’t allowed to vary overmuch.

These restrictions have made themselves known in multiple ways. In practice, the lack of node diversity has led to stranded resources. The most common complaint among HCI customers is that they have found themselves adding more nodes to a cluster than their performance requirements would otherwise call for just to get additional storage capacity.

Some customers find themselves with the opposite problem: they find themselves without the ability to add compute-intensive nodes offering adequately powerful CPUs or enough RAM without also committing to adding more storage to a cluster capacity than they actually need. In short, one of the most common criticisms of HCI is that the limited variation in appliances offered by vendors doesn’t satisfy the diversity of demand in the real world.

This lack of flexibility among major HCI vendors has some real world consequences for those seeking to refresh existing HCI solutions. One of the major promises of HCI was an end to forklift upgrades. All upgrades would be non-disruptive! Workloads wouldn’t have to come down during refreshes! Truly, a new age had dawned on the data center.

This non-disruptive upgrade only works if the HCI solutions in question are flexible enough to cope with clusters that have dissimilar nodes. Non-disruptive upgrades require adding new nodes to an existing cluster, live-migrating workloads over and then failing out the older nodes until they’re all gone. Perhaps the older nodes get reused for less critical workloads, or given over to test and dev, but the critical workloads need to move from the old to the new without fuss or headache.

Fortunately, not all HCI was created equal!

Refreshing the refresh cycle

Before HCI storage refreshes were horrible. Despite this, there was often still economic incentive to do them “early”, rather than in sync with compute. Especially during those lazy years when Intel had no real competition and this refresh cycle’s CPUs didn’t offer much over the last.

HCI changed this by allowing for rolling upgrades. A flexible HCI vendor provides organizations the ability to grow clusters as they need and to organize phased refreshes. Flexible HCI vendors offer not only pre-canned appliances, they work with channel partners to offer reference-architecture-based solutions with quite a bit of variability allowed per node.

The highest level of flexibility among HCI vendors comes from those willing to offer their solution as software-only, giving customers choice and allowing them to define their own needs. Software-only HCI solutions will run on any x86 server, whether brand-name or white box.  They will run on any server model from aged systems to the latest and greatest. They can work with any storage media and, in some cases, multiple hypervisors.

This is a dramatic change from how storage was done before HCI. There weren’t a lot of whitebox storage array offerings, nor was there much in terms of channel-driven reference architectures. Organizations could pick from among the pre-defined offerings and just sort of had to pray that when the next refresh came the vendor they had selected had some idea how to migrate from one array to the next.

An entire industry sprang up around data migration. Fortunes were made by those offering the ability to take data from one vendor’s storage solution and move it to another. Growing only as needed and smoothly migrating from one generation to the next were pipe dreams.

Against this backdrop, it’s little wonder that even inflexible HCI vendors able to deliver only limited customer choice were still able to achieve success.  Now, it’s time for organizations to demand more.

(Next page: The promise of HCI; software delivers)

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