The Growing Benefits of Flash Storage
When flash storage was introduced a few years ago, it broke new ground. It was ten to 20 times faster than a typical spinning disk. Sadly, it was so expensive that IT leaders could only justify using it for high-priority workloads. An online retailer, for example, might be able to justify using it for their website because it would provide the best experience to customers who expect instant gratification.
Then, a couple of years ago, vendors began incorporating advanced compression technology into their storage platforms. Users can now compress their data into half the amount of space, effectively slashing 50 percent off the cost of flash storage. On top of that, last year de-duplication made its debut. By eliminating redundant data, it can reduce the amount of data you need to store by five to ten times. Finally, thin provisioning, which slices up storage among users as needed, has also increased storage efficiencies.
With these new storage technologies taking hold and the price of flash storage declining, the cost-benefit equation has changed. When layered on top of compression and de-duplication, flash technology is within 20 percent of the price of traditional spinning disks.
Because of the new economics, more and more companies are installing flash storage. After all, it can reduce the five milliseconds read time of a traditional spinning disk to 0.5 milliseconds or lower. Theoretically, this speeds up IOPs by ten times. Of course, business leaders appreciate that there’s a big difference to a user between clicking on their screen and waiting ten seconds versus one second.
Leveling the Latency Spikes
Here’s a real-life example of the benefits of flash. A large government agency operates in the virtual desktop environment with hundreds, perhaps thousands, of users tapping into capacity from their data center. Every day, employees come in at 8 a.m., and they all power up their computers at almost the same time, creating a “boot storm.” Another peak in usage follows lunch.
During each of these periods, there used to be a substantial spike in latency, slowing down operations. The IT department associates could clearly see these peaks in the dashboard of Galileo, their IT infrastructure performance management solution. They were also able to determine that these spikes were the result of a read-intensive workload with high IOPs. Such workloads are most likely to benefit from flash storage. When they tested flash, they looked at the dashboard to see its effects and saw that it immediately flattened out the latency spikes.
Why Sometimes Flash Fails to Deliver Results
Even though flash may be doing its job, companies using it are sometimes disappointed. That’s because other technologies can impede its success as shown in the following two examples:
Weak Links in the Application Delivery Chain
If an application is CPU intensive rather than I/O intensive, it may not reap flash’s benefits. To learn what affects an application’s performance, you need to monitor all technologies in the application delivery chain and understand your performance metrics before installing flash. If your CPU and network are running at ten percent, you’re unlikely to experience a problem. However, if either one is at 90 percent, you probably will not realize the full benefit from flash unless you fix the problem. That’s because when flash increases the speed of IOPs, your network or CPU may become saturated. This creates a bottleneck that prevents the application from realizing flash’s benefits.
Make sure you look at performance metrics before and after you install flash storage, so you have a full understanding of what’s driving the speed of applications.
Fallout from Compression Technology
Another issue you might run into is that compression and flash are not perfect for everything. Some workloads, such as a transfer size larger than 64K with a sequential workload, are not compression friendly. In such circumstances, compression overhead interferes with the ability to experience the full benefit of flash’s low latency.
Because applications run on servers, you need an IT infrastructure performance management tool that looks at storage and servers to measure the benefits of flash storage and how other technologies affect it. Monitor performance before you try flash storage. From the data, make your best judgments as to whether flash is a good candidate for speeding up your application. If so, ask your vendor for a trial unit. Once you’ve installed it, continue to monitor performance to see if any other problems crop up in your IT infrastructure, such as CPU being maxed out, and address them. Most companies can benefit from flash storage if they do a thoughtful, data-driven analysis of performance before and after installing it and address any issues that emerge.