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Three Tips on Choosing Between All-flash and Hybrid Storage Arrays

Two of the hottest technologies in data storage today are all-flash and hybrid storage arrays as both systems can deliver performance in the tens if not hundreds of thousands of IOPS with some capable of achieving over a million IOPS. The challenge that now confronts organizations is selecting the right solution for their environment from this ever-growing, ever-changing list of storage systems. While no one right universal answer exists, here are three (3) tips that DCIG has gleaned from its conversations with end-users, vendors and resellers of these products that can help organizations make the best possible choice between these two technologies for their environment.

1. If only limited amounts of capacity are needed, choose an all-flash array.
 This piece of advice was shared with me just yesterday by an IT architect who spent nearly 18 months evaluating the various flash and hybrid solutions on the market. In the end what drove him to select an all-flash array over a hybrid array was that he knew his applications were not going to need a lot of capacity (less than 10 TBs overall.)
A hybrid storage array probably would have met the performance needs of his application but for the amount of capacity needed in his environment, he found the price differential between an all-flash and a hybrid storage array nominal (the all-flash array was just slightly more.) Since performance (or lack thereof) was a huge issue in his environment, he opted for the all-flash array. Using an all-flash array he would never have to worry about caching and tiering algorithms (such as are used in hybrid arrays) potentially negatively impacting application performance in his environment.
2. In converged infrastructures hybrid storage arrays are almost always a better choice. Most organizations find that only a relatively small percentage (as low as 2-5 percent) of their application data is sufficiently active to take full advantage of the performance that either all-flash or hybrid storage arrays offer. This particularly applies in converged infrastructures where organizations may host multiple applications on a single storage system.
In these situations, the capacity needs of the applications probably outstrip their performance requirements as the environments. As such, organizations should choose hybrid storage arrays as they can more cost-effectively scale the storage capacity of these arrays by adding more SATA and/or SAS HDDs without sacrificing application performance.
3. Regardless of the array type, choose one that offers application integration if such integration is available. Hybrid and all-flash arrays have become so fast that they are rarely a performance bottleneck. Storage administrators now tell me that queue depths (pending I/Os) on their servers have gone to near-zero if not zero. This situation has resulted in storage arrays waiting on applications to send them more I/O.
Already there is evidence that some application vendors are recognizing this as an opportunity to accelerate application performance by integrating their application with the underlying storage array. VMware is making this functionality available on these storage arrays to some degree with its VMware APIs for Array Integration (VAAI) and VMware APIs for Storage Awareness (VASA). All-flash and hybrid storage arrays that support these APIs should accelerate virtual machine (VM) performance hosted on these arrays.
As such, if looking at one of these arrays in the context of using it to host either VMware vSphere or View, verify the array supports these APIs.  If one array does support these APIs and another one does not, give the array (whether it is all-flash or hybrid) that does support these APIs preference as it will more likely outperform the other one.
A better example is the integration that Oracle has put in place between its Oracle Database 12 and its Oracle ZFS Storage ZS3 storage systems. Through its integration with Oracle Database 12 the ZS3 arrays recognize the Oracle Database Hybrid Columnar Compression (HCC) feature. Further, it capitalizes on the flexibility that Oracle Database 12 offers to optimize storage network traffic by sending packets in sizes that are optimized for improved performance.
While integration between applications and storage array is still in its infancy, expect more applications and operating systems to offer higher levels of integration with storage arrays in the months and years to come to both capitalize on their available performance as well as differentiate themselves in a crowded array marketplace.
It is worth noting that application integration is not necessarily specific to all-flash or hybrid arrays. If an array offers integration for an application that is in use in your environment, that array whether it be all-flash or hybrid should be given preference as it will likely outperform by a substantial margin other arrays that do not offer this integration.


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