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One of the key decision points for the IT professional is justifying the cost of a flash investment. Fortunately, thanks to the decreasing cost of raw flash memory, and the addition of various data-efficiency technologies, making the return on investment case is becoming far easier. The effective cost per GB of a flash product is low enough now that most data centers should consider it first -- rather than adding additional hard drives to an existing RAID group.
The benefits of flash and the payback on investment comes in two essential areas. First, it reduces the number of hard drives required to meet a performance demand. The second benefit is the increased number of virtual machines available per host, which limits the number of hosts you would need to buy.
Prior to the availability of flash, the primary method for meeting a storage performance demand was to add additional hard drives to the storage system.
Flash can eliminate this type of expansion. A small 1U flash array can take the place of an entire hard drive array. This forms the basis for a ROI case, since you aren't acquiring additional drives you would have needed without flash. Plus, those drives you didn't purchase won't need to be powered and cooled.
One of the other benefits of flash is the increase in virtual machine density. The physical server that is designed to host VMs is not like a typical server. It often has more CPUs, more memory and better networking. But since it's more costly, you don't want to buy more than you need. Most host server CPUs, in reality, are severely underutilized, often because of the storage I/O they can sustain. With flash memory, a data center is able to achieve greater VM density. This means fewer hosts and lower costs.
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