Originating Author: David Vellante
EMC’s January 14th, 2008, announcement further brings into focus the different philosophies of the major high end players. For EMC, the approach is to jam substantial functionality inside the DMX as the company continues to increase the granularity of its in-box tiered storage offerings. By adding an ultra-high performance tier 0 with the inclusion of NAND-based flash drives, EMC is targeting the 4%-5% of data that can exploit such functionality. Conceptually the company’s DMX device portfolio can be drawn like an HSM pyramid, originally conceived more than 20 years ago, now with 1TB SATA drives consuming the bottom layer of the pyramid.
For existing DMX customers, this is good news, although its attractiveness threatens to further deepen the reliance on EMC. Loyal EMC customers should continue to investigate virtualization engines such as EMC’s Invista, Hitachi’s USPVM and IBM’s SVC as a means of rationalizing applications that don’t need to reside on the highest end systems. Building this type of flexibility into the storage portfolio will reduce software and maintenance costs, keep service levels aligned with requirements and simplify migration in some cases. Indeed, while EMC’s Virtual Provisioning will dramatically accelerate storage allocation, many of the migration and data movement complexities remain and this type of strategy can help considerably.
One added concern of users for flash-based tier 0 devices is the durability of the drives and specifically the writes per cell the device can handle. One potential issue is if drives are wearing they may need to be serviced more frequently than conventional disk drives. However while native NAND flash technology has been rated for at least 100,000 writes per cell, EMC, and STEC, the OEM supplier of the devices to EMC, have worked around this problem and extended the longevity of the device by performing ‘wear leveling’ across extra capacity (~2X) built into the device manufactured for EMC. It is not unreasonable to expect these devices to outlive the useful life of an array.
On balance, many in the Wikibon community believe these devices have been specified conservatively by STEC and EMC. A vendor with EMC’s track record leads us to believe this is the case, however no one really knows for sure. The devices have only been in the market for a year, and these estimates are based on accelerated life tests by the vendors.
Action Item:Users should be encouraged by EMC’s latest announcement as it gives them clear reasons to keep investing in the platform. As expected, many of the functions announced are also available to DMX-3 customers, as EMC has done its typically good job of protecting previous investments while holding a carrot out for customers to move to the DMX-4 (flash and 1TB SATA devices). Customers should understand how EMC and STEC have increased the reliability of NAND-based flash devices, identify candidate applications and begin testing the function in high performance applications.