How to look beyond price when considering flash storage

If you want to add flash storage, says one longtime stakeholder, it's important to consider, among other things, the cost per IOPS and gigabyte compared to HDD volumes.

Jeff Rowe | Dec 04, 2017 12:00 am

As with any significant IT infrastructure purchase, when it comes to flash storage, price isn’t everything.

Pointing to just one example of the need to look at the big picture, longtime hospital CIO Brian Posey recently used the example of the cost of IOPS. “It's possible to achieve high numbers of IOPS by striping together hard disk drives, but it could take an excessive number of HDDs to reach the desired level of performance,” he suggests. “Flash drives deliver a much higher number of IOPS than HDDs, so it is possible that using flash storage may reduce overall costs, even if the cost of flash drives is higher than HDDs.”

As he sees the storage landscape, one reason flash storage has a reputation for being expensive is that flash drives have relatively low capacity, so the cost per gigabyte is high. “But using HDDs for high-performance workloads can actually cost more because you need more of them and could end up with wasted capacity . . . If you only look at the cost per raw gigabyte of storage, then high-performance, high-capacity HDD volumes have a low cost per gigabyte. But if you look at the cost per gigabyte of the storage that your workload will actually use, the cost per gigabyte is much higher. The latter comparison makes HDD and flash storage analogous, especially for high-performance workloads.”

Another concern Posey mentions for IT managers determining the cost of flash storage is the hardware refresh cycle. “Most organizations replace their storage arrays every five to seven years. But the drives within those arrays may need to be replaced more frequently depending upon how often users access the data stored on them.”

Not so long ago, he notes, flash storage had a reputation for having a short lifespan because the NAND chips wore out quickly, but that has changed as manufacturers have significantly improved flash storage durability. “Not only have the NAND chips themselves improved, but technologies such as wear leveling help to extend the life of the drives by distributing write operations evenly across the available cells.”

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