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Should you stick with hard disk drives (HDDs) or move towards solid state drives (SSDs)?
Many are pondering that question. For some, the answer might be all flash; for others it could be to remain on disk. But for most, these days the solution probably lies somewhere in between, on a platform that known as hybrid storage that offers some disk and some flash.
Here are some pointers to help you decide.
1. Check Out Real Cost per GB
Key features to look at include real cost per GB. Reason? Some flash array vendors, for example, quote a price per GB based on a hypothetical deduplication or compression ratio. Users, therefore, need to make sure they are comparing apples and apples when reviewing costs.
“To do so, ask their vendors to provide three prices,” said Thomas Isakovich, CEO and founder, Nimbus Data. “Raw cost per GB, usable cost per GB (accounting for data protection, flash management, redundancy, etc.) and potential cost per GB, calculating potential cost/space savings achieved through deduplication and other schemes.”
2. Consider Scalability
Most flash arrays are limited to less than 15 TB of usable flash (before dedupe) per array. Many users, however, require more than this. It’s a case of comparing hybrids to all-flash arrays. Those needing capacity as well as performance could find hybrid arrays to be an attractive proposition.
“Ask how all-flash systems scale capacity non-disruptively and what the limits are,” said Isakovich. “Determine whether the architecture scales capacity with bandwidth and cache in concert to ensure performance is improved at scale.”
3. Fit the Array to the Application
Vendors generally argue that their arrays are better than those of the competition in every possible way. But this is too narrow a view. What is a more realistic position is that some hybrid arrays are better suited to certain use cases.
“Look for an array that matches your needs, because many of them are tuned to a specific application: Databases, virtualization, OLTP, etc.,” said Jim Handy, an SSD analyst at Objective-Analysis.
4. Match the Array to the Topology
Handy offers another piece of good advice—to match the array to your data center's topology, since some are designed to be attached as DAS while others operate as SANs.
“Also, some are High Availability (HA) with no single point of failure (SPoF) but others aren't,” he said. “You pay a premium for these extra features.”
5. It’s Not Just About Performance
Most of the time, the discussion about flash storage has been dominated by performance. Vendors are trying to reach stratospheric levels of performance, while ignoring the other dimensions of storage that matter: cost, resiliency, ease-of-management, and features.
“Users should focus on software features and affordability,” said Matt Kixmoeller, vice president of products at Pure Storage. “Does the array include HA, scalability, deduplication, compression, snapshots, replication and multi-protocol support?”
6. Don’t Overdo Flash
Because SSD is popular, many users are keen to deploy it. However, in some cases, they may be choosing far more flash than they need.
“In general, most mixed workloads require less that 5 percent of the capacity of the system to be SSD for read cache,” said Lee Johns, vice president of marketing and product management, Starboard Storage Systems. “Many can benefit significantly from as little as 1 percent of the capacity being SSD. The size of the write cache required depends on the write profile of your applications.”