NAS closes in on DAS

By Bob Zimmerman

Direct attached storage has been the technology of choice especially since fiber channel (FC) connection has become the de facto standard for external disk arrays based on performance and cost. Networked storage is the coming dominant technology, with the focus on storage area networks (SANs) in most enterprises; network-attached storage (NAS) may have installed more boxes but tends to be smaller, application specific or delivering departmental capacity. NAS has been restricted by the following:

• File-level processing, great for stream I/O or backups, but not ideally suited for database applications
  
  

3Ware and Lefthand Networks, among others, have tackled the block I/O vs. file-level processing challenge. Once a pure NAS block-level I/O solution is pervasive, expect all of the database vendors to formally support NAS. Today, only Oracle actively certifies NAS database solutions; IBM and Microsoft database products work fine, but don’t certify.

Network Storage Systems announced recently that it has developed a NAS engine based on of-the-shelf components that runs four times faster than its predecessor. This technology evolution has proven that NAS does not depend on breakthrough storage engineering and is destined to become commodity storage. In the same vein, there is a glut of industry standard DRAM and processor chips. More and more of the NAS vendors are choosing either Windows or Linux for a base operating environment built on these electronic components. Over time, a standard base will allow these vendors to deliver custom storage solutions, rather than simple capacity, by integrating applications into their NAS products.

The appearance of multi-Gigabit Ethernet (GbE) has removed a performance bottleneck, and Blue Arc is first in taking full advantage of it, albeit with proprietary network interfaces. Blue Arc may be the vendor that proves the rule, however, as it continues to rock the industry with amazing performance. Its Si7500 set new benchmarks for NAS of 1,782 megabits per second (Mbps) throughput in Iometer tests and 1,315Mbps at an average response time of 0.71 ms in NetBench tests. (Iometer is an Intel stress load test and NetBench is a Ziff Davis server/network I/O measurement utility; for details see www.etestinglabs.com/main/reports/bluearc.asp.)

Over time, expect Blue Arc to license its technology to create a broader market and market acceptance while attempting to derail competitive technologies. The important of the millisecond response cannot be overstated, true database applications and online transaction processing (OLTP) depend on disk responsiveness. Factor in this very responsive NAS on standard components with built-in storage applications, and the distinction between SAN and NAS becomes even more blurred, with convergence questions centered on security, not openness. Once the IP-based storage model solves the security issue, NAS and iSCSI based SANs will dissolve an artificial technology boundary.