An all-flash array is supposed to be the pinnacle of storage performance but these systems have a secret; they are leaking performance. Proof of this is simple, take the raw IOPS of the drives inside the typical all-flash array and multiply it by the number of drives, then compare that to the rated performance of the system. In almost every case, there will be a massive difference between the two, with the storage system coming up on the short side of the equation.
Why All-Flash Arrays Leak Performance
The performance leak is not a result of the networking or media that storage systems use even though these are the components that most IT architects attack when looking to improve performance. The problem is the CPU and the software that drives the system.
In truth the storage CPU isn’t really the problem, it’s just that Intel changed the rules and storage software developers didn’t keep up. For years Intel increased performance by adding additional processing power to the main CPU, now however Intel increases performance mostly by adding cores. Intel claims it is continuing to improve performance when for the most part the performance gain is the aggregate of multiple cores.
There is nothing wrong with gaining performance via multiple cores but software has to become more multi-core aware and be able to better parallelize itself across those cores. Most storage software solutions claim multi-core capabilities but their utilization of multiple cores is relatively rudimentary.
The Storage Software Leak
The performance leak is more than just software not being multi-threaded. All-Flash arrays are also leaking storage because they are using old algorithms and code. Many all-flash vendors borrow code from either open-source or old projects to deliver various features like media failure protection (RAID), volume management or snapshots. The problem is that the technology has changed both in terms of the media type (memory), the CPUs (multi-cores again) and the development tools that are used to create the software in the first place.
The Impact of the Performance Leak
A large swimming pool with a small leak in it can still do the job; provide a refreshing way to cool off in the summer. But, the pool will require more water than it should to do its job. A leaky all-flash array has the same problem. Although the vendor may be able to put enough CPU and drives in the system to deliver the performance the data center needs, it is forcing the organization to buy much more storage system then they should actually have to. The effect is that all-flash arrays cost more than they should and don’t perform as well as they should which means less data is on flash and applications don’t respond as fast as they could.
There are two key storage trends facing the enterprise. First, the storage system is becoming more software defined and second, hardware is no longer the primary performance bottleneck. Now software matters but most SDS solutions count on legacy and/or publicly available code resources.
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