From day one, it was Nimbus’ vision to build a 100% solid state storage system with the software and networking capabilities of high-end 15K rpm disk arrays at a comparable acquisition cost per gigabyte. With the S-Class, Nimbus has accomplished this ambitious goal. The table below breaks down the acquisition cost per usable gigabyte of Nimbus S-Class flash memory systems compared to an enterprise-grade 15K rpm disk array with comparable software capability. For a complete analysis, see the full report below.

  15K rpm Array Cost / GB Nimbus Flash Cost / GB
Hardware $6.00 $10.00
Capacity Overhead


Software Licenses


1st Year Support $2.00 $1.00
Total Usable Cost / GB $14.00 $13.00

Software is one of the highest contributors to enterprise storage system cost. In fact, software licensing is the profit engine of the large incumbent storage vendors, often charging fees for enabling features, or even double-charging end-users for features on systems with dual controllers. Nimbus, on the other hand, does not charge by the feature. Nimbus' HALO Storage Operating System provides one of the most comprehensive software stacks for enterprise storage available, including features like multi-protocol iSCSI, Fibre Channel, Infiniband, NFS, and CIFS support, snapshots, replication, deduplication, and thin provisioning, all managed through one intuitive interface (both web and command line). Taking the software cost out of the equation eliminates a large contributor to cost per usable GB, lowering total acquisition cost.

No moving parts means the risk of mechanical failure, the top cause of hard drive failures, is eliminated. Furthermore, since flash is resistant to vibration, cascading failures are worries of the past. Flash also generates less heat since it draws much less power. Excessive heat is a contributor to premature hardware aging, and the lower operating temperature of Nimbus S-Class systems translates into a more hardware-friendly environment. Finally, in the event that a flash module fails, it is likely that Nimbus’ automatic recovery will rebuild to a spare flash module before anyone was aware of the issue, reducing rebuild time from hours to minutes. All these reliability enhancements mean that Nimbus assumes less cost in supporting customers, and in turn can pass these savings on to end-users in the form of lower maintenance costs.

You may have faced the following scenario before. Your brand new 10 TB disk array is installed in the rack, and you are ready to provision it. By the time all that setup is done, your 10 TB array suddenly has just 6 TB of capacity to share. Where did those 4 TB go? You may be surprised how inefficient file systems can be. For example, some solutions preallocate 30% of the storage for future snapshots upfront. Some systems store logging information on the very storage you just bought, rather than storing on dedicated media. RAID overhead can present another 20% tax depending on aggregate limitations and other configuration restrictions. With Nimbus, however, capacity overhead is about 50% less. Our RAID algorithm can pool an entire system into a single RAID group, minimzing parity and hot-spare overhead. Because our file system is fully thin-provisioned, we do not preallocate any capacity for future snapshots. Finally, Nimbus system software runs off a dededicated embedded flash disk-on-module, not the actual storage you purchased. All of these factors add up to give Nimbus the best physical-to-usable ratio of any enterprise storage system.

As shown above, when you consider the fully-loaded cost of hardware, software, capacity overhead, and the initial year of maintenance, Nimbus S-Class flash systems can compete with the acquisition cost of conventional 15K rpm arrays. Now let's look at the total cost of ownership of 10 TB of usable capacity. Impressively, this is where flash-based infrastructure truly shines by reducing maintenance cost and cutting variable expenses, like power and cooling costs, by 80% or more.

  15K rpm Array Fixed Cost Nimbus Flash Fixed Cost
Acquisition Cost $143,360 $133,120
Years 2 -5 Support Cost


5 Year Fixed Cost $225,280 $174,080

  15K rpm Array OpEx Nimbus Flash OpEx
Power Usage (kWh) 13,140 2,190
Cooling Needs (BTU)


5 Year OpEx Very High 80% lower

Finally, in conclusion, let's quantify the value of solid state's outstanding performance. Afterall, this will be a key motivating factor to adopt flash memory storage instead of spinning disk. In the table below, we take the fixed 5 year cost above for 15K disk and Nimbus Flash, and calculate the cost per IOps and cost per MBps, making assumptions for performance of the two offerings.

  15K rpm Array Nimbus Flash
Cost per IOps $11.26
@ 20K IOps
@ 800K IOps
Cost per MBps

@ 500 MBps

@ 8,000 MBps


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