All Flash or Hybrid - Business Case First Technology Choice Second

An increasing number of storage solution providers are offering all-flash arrays (AFAs) because of the growing demand and at the same time, the decreasing price of this technology. This growing trend in the market landscape is making IT companies question whether they should go with the trend and make the switch.

When deciding on a storage solution, most IT managers will choose between hybrid and all-flash storage. A hybrid consists of SSDs and HDDs while an all-flash system uses only SSDs. In a hybrid unit, the HDDs host cold data while the SSDs are used for hosting hot data. In an all-flash array, the SSDs host both hot and cold data. When comparing hybrid and all flash units, a big part of the focus will be placed on latency. Hybrid arrays are going to have latency that is higher than an all-flash array.

Data centre workload is typically the first thing to look at when deciding if an all-flash or hybrid solution is best suited for the company requirements. For example, a database and OLTP systems that require low latency and high IOPS will be better suited in an all-flash array, while workloads that transfer data in a more direct fashion can be served by a hybrid solution. Application needs and requirements are ultimately the deciding factors when choosing between AFAs and hybrid storage.

AFAs are useful when the entire working set is hot or all data is used all the time so everything needs to be very fast. AFAs make sense for environments that need performance all the time like extreme OLTP environments. Another thing is when there is a requirement for consistently guaranteed low latency regardless of access.  Companies also tend to go for AFAs when performance requirements are more important than budget. Hybrid arrays are useful for typical access patterns in the environment. Hybrid arrays are good for anything that needs some high performance but not everything high performance. Companies don’t need everything to be on all-flash or environments that can work well when only a part of it is on all flash.

The bottom line is that whether to go with a hybrid or an all-flash storage solution depends entirely on the company’s infrastructure needs, and there are a number of factors that affect this decision. AFA storage seems to be a trend that will inevitably take over. But a hybrid storage solution can still be a very cost-effective option for workloads that don’t require the highest levels of latency and IOPS. There are benefits to both arrays, and it is essential to know everything about the environment and infrastructure before deciding on what storage solution to use. Capacity utilisation, IOPS usage, reads and writes, network bandwidth performance, server statistics, hot data versus cold data and application performance all play into which type of storage solution an IT company should choose.

It may sound strange, but ultimately the decision is not a technical one. It is true that technicians that understand enterprise storage can support the decision by providing intelligence around price and performance. However, the over-riding decision should be made around what does the business need. Business questions such as how is customer perception affected by the performance of our applications? Is our workforce productivity impacted due to the transaction time of our databases? Do the business benefits we derive from implementing a certain class of storage outweigh the fully loaded cost of running that storage? These are the questions that the business needs to ask, the answers combined with knowledge of the performance of a given type of storage will ultimately guide decisions around technology choice.

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