A New Foundation For Storage

For the last several decades the underlying elements of data storage-disk drives, drive enclosures, and controllers-have remained more or less the same, and have been unable to keep pace with dramatically changing business requirements. Xiotech offers a fresh approach with its Intelligent Storage Element: A storage foundation that sets new standards for reliability, performance, and scalability.

Happy Anniversary!

This year the channel-attached disk drive turns 54 years old (IBM RAMAC in 1954), and the internalbus- attached disk drive turns 35 years old (Winchester 30/30 in 1973). RAID had its beginnings 30 years ago (Norman Ken Ouchi of IBM was awarded a patent for what would later be termed RAID 5 by Patterson, Gibson, and Katz in 1988), and the SCSI interface celebrates its 22nd year (published as an industry standard by ANSI in 1986). This turns out to be a very long run for what are still the fundamental foundations of today's storage systems.

Since the advent of the Small Computer System Interface (SCSI) and the realization of a Redundant Array of Inexpensive Disks (RAID), data center disk storage has matured to its present form that we know as modular or monolithic disk arrays. These arrays are available with various interconnect protocols and in various capacity points and performance levels. However, the essential elements of data center storage (disk drives, drive enclosures, and controllers) have changed little over the years. In relation to this foundation, neither IT operations nor fundamental element characteristics have changed significantly.

We still perform SCSI I/O to a set of disks fastened in an unintelligent enclosure. We still rebuild disks when they are flagged as failed. We perform RAID as a one-dimensional stripe of data over a given set of disks.

In addition, the fields of architecture and statics teach us that a structure is only as strong as its foundation. This principle, when applied to modern disk arrays, means that we cannot progress much further (outside of capacity increases) unless we completely redesign the foundation to become much faster, more reliable, and more intelligent than it is today. Only in this manner can we progress beyond the decades-old disk storage paradigms in place.

ISE: A New Foundation

To overcome these issues, in 2007, Xiotech acquired the Advanced Storage Architecture (ASA) group from Seagate Technology. This group of talented engineers and designers was informally known as the "Skunk Works" in respect to the legendary design group at Lockheed Martin. Like the original Skunk Works, the ASA group designed and built a revolutionary machine-the Intelligent Storage Element (ISE).

The design of the ISE incorporates innovative and disruptive thinking around the foundation of storage-the disk drive and its enclosure. With its game-changing design, the ISE delivers reliability, performance, and scalability that no other storage system today can match.

Unprecedented Reliability

The ISE reaches reliability levels impossible for standard drives and enclosures, providing more than 100 times the reliability of a regular disk drive enclosed in a typical storage system drive bay. This is a stunning figure-it means that an ISE, on average, will incur zero service events in five years of operation.

Because of this extreme reliability, Xiotech offers a revolutionary 5-year warranty for its ISE hardware.

• Significantly improved environmentals.
  The ISE is designed to dramatically reduce heat and vibration-the two greatest causes of drive failure.



• ANSI T10-DIF.
  The ISE is one of the first storage systems to incorporate ANSI T10-DIF for end-to-end error correction and detection and the prevention of silent data errors.


ANSI T10-DIF provides three types of data protection:
• Logical block guard for comparing the actual data written to disk.
• Logical block application tag to ensure writing to the correct logical unit (virtual LUN).
• Logical block reference tag to ensure writing to the correct virtual block.


• Self-healing technology.
  The ISE automatically performs preventive and remedial repair of components within its sealed DataPac (capacity module)-requiring no intervention to pull failed drives. The ISE migrates data as needed, performs power-cycling and factory remanufacturing, recalibrates compo nents, and more. The result is the equivalent of a fresh, factory-remanufactured drive. Only the components that are irreparable are taken out of service. All others are restored to full activity.



• Granular recovery.
  The ISE can recover data down to a level of granularity impossible with traditional RAID controllers that can only "see" an entire drive.



• Self-Sparing.
  Each sealed array includes spare capacity, which overcomes the need for service if there is a failure within the DataPac.

Industry-Leading Performance

As systems grow, the compatibility burden and centralized management limit overall system performance and reduce the intelligence available for higher-level storage functionality. The ISE overcomes these issues by tightly integrating the drive, enclosure, and controller software and firmware, and by distributing much of the processing and cache into the enclosure.

RAGS Is the Key
The software portion of the ISE is built on a new Redundancy Allocation Grid System (RAGS), designed to reduce processing complexity and provide more robust functionality with no loss in software reliability.

The RAGS software architecture uniquely provides:

• Improved data organization for high-speed rebuilds, maintenance operations, and replication (45 percent faster rebuilds than any known array).
• Optimal actuator profiles for each DataPac within the ISE.
• More efficient striping.
• Less qualifying to achieve bug-free interaction between controllers and groups of disks.

Adding processing and cache with each ISE and the new RAGS capability result in previously unattainable levels of performance.

ISE performance was recently validated by the Storage Performance Council (SPC).

• Lowest cost per SPC-1 IOPS for disk-based systems
• Excellent cost per SPC-2 MBps

Maximum Scalability

In the architecture of storage systems, the key to achieving scalability is to reduce complexity and linearly scale such things as processing and cache to avoid large system bottlenecks. The ISE achieves this simplified scalability by pooling storage to create a singular storage element that is 20 to 40 times the capacity of a typical disk drive, with the internal processing power and cache it needs to handle all drive management functions.

Storage solutions can be created using the ISE in a building block fashion, starting as small as a single terabyte and growing, as needed, up to a petabyte within a single system.

The ISE can be part of a direct- or switch- attached System (e.g., EmpriseT 5000 from Xiotech). Single or multiple ISEs also can be utilized in a controller-based storage area network system (e.g., Emprise 7000). The environment can even evolve, using an Emprise 5000 system, for example, as the foundation of an Emprise 7000 solution.

Finally, the ISE foundation enables tremendous performance scalability. Because the ISE includes cache and processing power, each time capacity is added, performance grows-in a linear fashion for Emprise 5000 systems. This scalability and incremental growth enable organizations to buy only the storage required, manage very large capacities from fewer systems, and grow from very small to very large without forklift upgrades and model family changes.

Conclusion: A Platform for the Future

Computing has changed significantly in the last twenty to thirty years. Adherence to Moore's Law has led to exponential growth in processing power, network throughput, and storage densities. Business practices have driven an ever-increasing demand for storage in terms of capacity, availability, and protection. At the core of it all are the decades-old disk drive, RAID, and SCSI technologies, all wrapped in an accumulated protective layer of complex and expensive fixes to make up for their shortcomings.

The ISE is a fresh new approach to the fundamental aspects of storage, setting new standards for reliability, performance, and scalability. Rather than shoring up the foundation that has been with us for decades, the ISE is a new storage foundation that promises to fulfill storage needs well into the future.

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