itx with RAID-RT Robust Raid Technology Whitepaper

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Collin Lee
6 years ago
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1 itx with RAID-RT Robust Raid Technology Whitepaper WHITEPAPER

2 Introduction RAID (Redundant Array of Independent Disks) technology constitutes the very foundation of network storage servers today, and its ubiquity and importance cannot be questioned. Conceptually, RAID is very simple. At its most basic, extra hard disks are added to a storage array to store additional information about the data residing there. If a disk failure or error occurs, the data stored on the array can easily be recovered from the redundant information stored in the system. Depending on the value of the data being stored, several different RAID levels are available to balance different levels of cost, performance and reliability needs. In spite of its ubiquity, to a certain extent RAID still remains one of the lesser understood areas of data storage technology. Broadly speaking, RAID can be implemented either as Hardware RAID or Software RAID. Hardware RAID uses one or more RAID Host Bus Adapters (HBA) to handle RAID functions, whereas for Software RAID, the RAID logic is performed by the host CPU. Almost every Operating System on the market today comes bundled with some form of Software RAID functionality. However, these freebies typically suffer from limitations and inadequacy and are often looked down upon as budget RAID. Naturally, the design and implementation of any Software RAID package contributes greatly to its ability to distinguish itself from a somewhat mediocre crowd. RAID-RT, the Software RAID module featured in StorTrends itx Network Storage Software from American Megatrends (AMI), is designed and implemented with class-leading, robust technology that gives it preeminence in the widely-varied RAID landscape. WHITEPAPER 2 Proponents of Hardware RAID typically tout its superiority over Software RAID, and until the advent of RAID-RT, these claims have been easy to justify. This whitepaper will take a closer look at what RAID-RT has to offer, to show that things have indeed changed and Software RAID is no longer relegated to the rear of the pack. Before addressing some of the myths surrounding the supremacy of Hardware RAID, consider just a few of the more obvious disadvantages of Hardware RAID controllers:

3 The dollar cost of the storage server increases when a Hardware RAID HBA is selected An additional PCI slot in the storage server is required for the HBA Power consumption increases due to the additional processing power needed Addition of hardware components to the storage server expose the array to potential increased component failures, which could affect its availability This whitepaper will also focus on areas where RAID-RT not only bridges that performance gap between Software RAID and Hardware RAID but in fact moves to the forefront, such as: Off-loading of processing tasks Hardware RAID accelerator engines Robustness in fault handling RAID manageability Superior I/O cache Enterprise-class clustered RAID for High Availability Effective CPU Utilization Supporters of Hardware RAID often claim that because RAID HBAs use their own CPUs, Hardware RAID reduces the computing burden on the storage server CPU, in direct contrast to Software RAID. In truth, however, with the introduction of more powerful CPUs in storage servers many of them available with multiple cores - this notion is no longer accurate. The host CPUs typically used in today s storage servers, such as multi-core Intel Xeon processors, have grown exponentially in performance and features compared WHITEPAPER 3

4 to the I/O processors employed in Hardware RAID and offer more than enough processing power to offset and additional burden that Software RAID may present. Typical storage server CPUs run at three to four times the clock speed of average Hardware RAID I/O processors. Moreover, nearly all storage server CPUs now use multi-core 64-bit architecture, in direct contrast to the singlecore 32-bit architecture of typical Hardware RAID HBA CPUs. Present-day storage server CPUs also have larger L1 and L2 caches in comparison the CPU cache sizes in RAID I/O processors - a factor that is of the utmost importance in delivering extreme high performance computing. Figure 1: Optimal CPU Utilization RAID-RT takes full advantage of the technological advancements in the latest storage server CPUs to deliver a leading-edge software RAID solution. Hardware Accelerators WHITEPAPER 4

5 Proponents of Hardware RAID point out that it utilizes hardware assists (sometimes referred to as accelerators ) to implement some of the more compute-intensive RAID functions. This is most often utilized at the more advanced RAID levels, typically RAID 5 and RAID 6. RAID employs special parity calculation logic for RAID 5 and Q-syndrome calculations for RAID 6. The computations involved in RAID logic are termed as Single Instruction - Multiple Data, or SIMD. Here, a single instruction, such as Parity XOR, is applied to multiple data streams from disparate physical disks in the array, as shown in the illustration below. Figure 2: Single-Instruction-Multiple-Data (SIMD) Operation Typically, Hardware RAID employs parity calculation engines or hardware assists to off-load these tasks from the CPU. Most high-end storage server CPUs today feature a special Multimedia Extension (MMX) logic, included mainly for the purpose of acting as accelerators for SIMD calculations used in RAID logic. RAID-RT takes full advantage of the MMX extensions present in today s powerful CPUs to make easy work of accelerated RAID computations. WHITEPAPER 5

6 Figure 3: Intel CPU with Multimedia Extension (MMX) The advantage of using MMX becomes evident particularly with storage servers featuring multi-core CPUs, which can leverage the power of multiple MMX computation elements, in contrast to the single hardware accelerator available in a Hardware RAID HBA. Besides the numerical advantage, these MMX engines run at considerably higher clock speeds than Hardware RAID accelerators, and thus offer higher RAID computation throughput. Robustness Another point to address is the notion that Hardware RAID offers a more robust solution for error handling. While this is generally true in comparison to conventional Software RAID, RAID-RT - with its stellar Robustness Technology - takes Software RAID to new heights of performance and reliability. It incorporates a sophisticated fault-handling module on top of the classic RAID logic to impart ruggedness and powerful error recovery at a level never seen before with Software RAID. WHITEPAPER 6

7 Manageability Traditional Software RAID implementations typically employ what could be described as a lackluster approach to manageability compared to enterprise-class Hardware RAID. One of the key areas where Software RAID was left lacking was in its support for vital RAID status LEDs and enclosure management indicators. These are, of course, excellent visual tools for the IT Administrator to quickly understand the status and performance of a storage server and manage it accordingly. Figure 4: RAID Enclosure Management LEDs In contrast to older, less sophisticated Software RAID, RAID-RT from AMI cuts no corners, offering full RAID status LED functionality and complete enclosure management. Because RAID-RT is a component of StorTrends itx, it is completely integrated with the ManageTrends web-based GUI, which features an intuitive interface and configuration wizards to help manage RAID arrays, along with an event notification feature that sets it miles apart from the competition. WHITEPAPER 7 I/O Cache

8 Hardware RAID controllers feature an I/O read / write cache which is critical to delivering high I/O performance in a busy system. Traditional Software RAID lacks this feature and as a result suffers in certain areas related to I/O performance. To address this shortcoming, RAID-RT comes integrated with ACM - a state-of-the-art Advanced Caching Module. ACM maintains block-level usage information for user data, something that is typically not present even in enterprise-class Hardware RAID solutions. For example, ACM maintains and tracks specific block-level metadata information to enables StorTrends itx to provide boot acceleration and lightning-fast snapshot I/O performance. ACM also enables StorTrends itx and its RAID-RT Software RAID module to deliver extreme I/O performance far exceeding the abilities of Hardware RAID cache logic. RAID Clustering RAID Clustering is of great importance for enabling highly available, dualredundant storage servers. It is typically considered to be a high-end feature that is only supported by a select few enterprise-class Hardware RAID solutions. Until now, legacy Software RAID modules have not implemented RAID clustering, but RAID-RT has taken RAID clustering to new heights by implementing a complete Active/Active clustered RAID logic for shared disks. Figure 6: Clustered RAID on Shared Storage WHITEPAPER 8

9 Comparison Chart Table 1: Comparison of RAID-RT, Generic Hardware and Software RAID Capabilities Conclusion RAID-RT from American Megatrends builds a robust layered architecture around a high performance RAID core, with its innovative implementation and optimal utilization of the high-end features of present day Xeon processors. In doing so, RAID-RT far outweighs Hardware RAID controllers in a multitude of areas such as hardware acceleration, robustness, I/O cache handling, and RAID clustering support. Why StorTrends? Consider StorTrends for your RAID solution because StorTrends from American Megatrends, Inc. is Performance Storage with Proven Value. StorTrends SAN and NAS storage appliances are installed worldwide and trusted by companies and institutions in a wide range of industries including education, energy, finance, state & local government, healthcare, manufacturing, marketing, retail, R&D and many more. StorTrends enables users with the features and tools necessary to meet the challenges and demands of today s business environments by offering key network storage functionality such as unified storage, simplified management, business continuity, disaster recovery, high efficiency and virtualization support. Since 2001, StorTrends has built a community of over 1,000 satisfied customers thanks to award-winning products, integrated data protection and world-class support, while continuing to enhance its products with patented enterpriseclass features. For more information on StorTrends solutions from AMI, visit to sales@ami.com, or call U-BUY-AMI. WHITEPAPER 9

Tech Sheet Benefits of Dual Redundant Active/Active Storage Architecture

Tech Sheet Benefits of Dual Redundant Active/Active Storage Architecture Tech Sheet Introduction Storage servers constitute the very foundation of any data center and their features, performance and scalability