What is Tiering?
Tiering is the most efficient approach to IT disaster recovery. It refers to a staged system recovery based on a pre-determined sequence of steps, or tiers. Each tier represents a different level of prioritization for the most important functions of your business, as well as the most important IT functions. The highest tiers represent those business functions with the most complete recovery point objective (RPO), and the fastest recovery time objectives (RTO).
For example, you might determine that recovering Blackberry service, email, corporate intranet and phone/voice mail has a two-hour RTO, making it the first tier of recovery, while document recovery and payroll has a 24-hour RTO, making it Tier 2.
How Does A Business Determine Which Functions Belong To Which Tiers?
IT DR tiers are formed by a combination of two things: your priorities according to business requirements, and the technical dependencies relating to the IT sequencing of your systems. It is always a compromise between the two. You take your business priorities, and then adjust them based on the technical realities of your recovery process.
Complexities inevitably arise due to the technical inter-relationship between your systems and applications. For example, it’s not unusual to have a customer service system that is highly integrated with an inventory system, or an invoicing system highly integrated with a finance system.
When you tier, you sometimes have to sequence recovery so that certain applications come up together, which may mean that a high priority application gets grouped together with a lower priority application in the top Tier, because both were integrated on the same platform (e.g. shared processing or storage systems).
Can You Automate the Tiering Process?
Determining the makeup of your tiers is a manual, decision-oriented process, involving discovering and uncovering the elements of your systems, as well as deciding on the priorities of your business functions. And then the whole thing has to be vetted by the IT people who design the sequencing of the tiers.
This is all a hands-on process, and sometimes a very time-consuming one at that. However, once the decisions have all been made and vetted, then the DR process can indeed be automated within your plan and rolled out on a logical basis.
Are There Any External Factors Involved?
Key stakeholders in management need to get together and provide input as to the makeup of the tiers. But they quite likely need to take into account the needs and the views of customers, business partners or regulators in order to help them verify their decisions.
What Is Tiered Storage?
Tiered storage is an independent concept from tiered IT systems or applications. However, it can be used to prioritize accessibility and portability of backup and recovery data in order to address RTO or RPO requirements. Tiered storage is seen more as a data management issue tied to the optimization of cost versus performance (speed of access).
