Out with the old, in with the new
These technology advancements are driving a sea change in storage tiering philosophy. The old days of a fixed menu of four or five tiers of performance and protection bundles are giving way to an à la carte menu or buffet of available services. Performance characteristics and protection can now be each uniquely selected, then bundled into a consumable service. Performance no longer needs to be concerned about RAID configurations or even disk technologies if autotiering is implemented. An application no longer has to be allocated to a specific tier of storage based on its recovery requirements.
Recovery requirements can instead be policy-based, and that policy can be executed on any of the storage frames on which the application or its components reside. With distanced and local replication commonly table stakes in many data centers, applications can now map their tables, logging files and images on the appropriate storage array without concern for dependencies triggered by a sequenced disaster recovery. This is very much unlike the old days when only tier 1 was replicated and when ensuring all applications in that tier were on the same storage device was critical.
Today, storage tiering philosophy is driven by three mission-critical criteria:
- First, there is the need to understand scalability of the applications being serviced. How many ports will they consume? What is the current rate of port consumption? Can the planned target array handle that growth? What is the next step in scaling connectivity for that storage frame?
- The second is performance. While most consumers still cannot empirically define their requirements in terms of IOPS, latency, or bandwidth, these metrics are key components of the new storage tier, if it is to be accepted by the consumer community. Where autotiering within the frame has been configured, publication of a blended performance rate and a lowest and highest threshold should suffice. The scalability and performance attributes are the tier cost and service differentiators.
- The third criteria, data protection, is now a service selection option rather than a tier selection option. Policy-driven protection for operational and disaster recovery can be configured (and often is today) at the application level rather than the storage frame. This means a rigorous project introduction process, as well as change and release management processes, but nonetheless, different protection levels of RPO/RTO combinations can be applied to most arrays across the various tiers of scalability/performance using today's technology. Like protection, other characteristics such as encryption and immutability can be addressed in a similar manner.
Here comes the cloud
It's important to understand yet another trend, as cloud services become more prevalent. The cloud's chief characteristics are the ability of the service consumer to self-configure elastic storage, with the provider automating the provisioning process and, most important, generating a bill. Without billing, the internal cloud is like a three-legged stool with one leg missing. All the motivators for cost-efficiency and service improvement disappear without a financial incentive.
The final challenge in today's tiering philosophy is to develop and deploy a demonstrably accurate, fair, and transparent cost model and supportive billing process for chargeback or showback. This can be a challenge where multiple disks provide a single service tier under autotiering and technology has yet to provide orchestration and statistics at a level to make actual use billing feasible.
Blended costs are often the most appropriate answer today. Protection costs become relatively easy to calculate using a multiplier based on the additional storage that will be consumed during the protection retention cycle, perhaps loaded by some form or port or bandwidth cost. Encryption and immutability requirements provide their own unique but not unresolvable costing challenges, too. At the end of the day, in 2013, it's critical for IT to know the unit cost of deployed resources and to whom those resources have been deployed.
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