Based on a review of all-solid state storage systems, it may be time for IT professionals to re-think their strategy regarding the lifespan of storage systems.
The storage system lifespan is a critical part of a storage strategy for scheduling replacements, planning acquisition costs, and in calculating Total Cost of Ownership (TCO). The lifespan is used in the amortization schedule or depreciation for the purchased asset.
Two major technology factors are important to consider when changing the strategy for a storage system lifespan. The first is the use of scale-out storage systems and the ability to replace individual nodes transparently for a technology upgrade. I will deal with this case in a future article. The second factor for consideration is the use of solid state storage.
The lifespan of storage systems does not mean when the system is no longer usable or will have its “use by date” come to an end. It is really about planned replacement with several elements playing into the replacement motivation:
- Wear out. The system may have characteristics such as mechanical wear that causes the failure rate to increase, which leads to more costly service and potential impacts.
- Maintenance costs. There is a warranty period for storage systems and the maintenance costs begin to increase after that period. The costs become more prohibitive due to the increase likelihood of service required.
- Migration of data. Many storage systems do not have transparent or seamless migration of data to a new system. Scheduled replacement does not alleviate the problem but does make it a planned activity.
Solid state storage in the form of NAND flash today has different wear out mechanisms than spinning disks. Most storage vendors have been making tremendous strides in the improvement of managing the wear out issues in NAND flash. They have accomplished this by changing the methods in the way page erase is done and using shadow RAM to minimize the number of erases. These improvements have continued to increase the lifespan for those vendors that have made the technology investment.
Vendors of solid state systems are now quoting longer lifespans for their systems. There are two notable examples:
Pure Storage has changed its upgrade and maintenance model with an approach called Pure Storage Forever Flash. The approach includes a five-year maintenance plan with a free controller upgrade every three years when renewing the maintenance. With every upgrade, the maintenance terms for the storage system can be reset to the current pricing, which is expected to be lower.
Nimbus Data offers up to a 10-year end-to-end warranty for its system.
The warranty period and the upgrade plans will be competitive issues with vendors. Customers will see the economic benefit from the better offerings in TCO calculations and other vendors will have to react. The change can lead to longer term economics for customers with use of solid state storage systems. The change is also an indicator of the evolving technology with solid state NAND Flash. Flash is getting less expensive and use of data reduction is adding to the cost reduction. It is also a reflection of the current methods of purchasing solid state, which is generally for a specific purpose or application workload usage today which leads to a sizing to match those needs. As price changes and application capacity needs increase, another system is purchased, increasing the amount of solid state storage.
For vendors, the longer warranties can be costly if the systems do not live up to the vendor promises. Service Cost Estimates for storage systems are calculated on intrinsic failure rates or demonstrated failure rates where there is field data. The warranty period requires a financial reserve from the price of sales to cover the costs. The decision to extend the warranty is not made lightly by vendors but competitive pressures do factor into the decision.
It should be expected that more all solid state storage system vendors will extend the warranty for the system in some manner. The bigger issue for the customer is the change in the strategy for acquiring storage — and planning for replacement.
(Randy Kerns is Senior Strategist at Evaluator Group, an IT analyst firm).