RAID System Research Articles

Performance Analysis of Row-Diagonal Parity (RDP) Algorithm in RAID 6 and Its Application in Cloud Computing

With the explosive growth of information, there is an increasing demand for storage technology, and cloud computing has become a major trend with the continuous development of new technologies. Therefore, this paper aims to find superior fault-tolerant coding schemes and explore their potential applications in the field of cloud computing. This paper provides a brief introduction to the background of RAID systems and fault-tolerant coding; elaborates on the principles and encoding process of the RDP algorithm in detail; deeply analyzes the application and performance of the RDP algorithm in RAID-6, and a comparison was made with RDP coding in cloud storage; and analyzes the development potential and specific application scenarios of the RDP algorithm in the field of cloud computing. Based on the above analysis and research, this paper affirms the development potential of the RDP algorithm in cloud storage based on cloud computing. It also proposes the research direction of the RDP algorithm in the field of cloud computing.

RAID: Regression Analysis–Based Inductive DNA Microarray for Precise Read-Across

Chemical structure-based read-across represents a promising method for chemical toxicity evaluation without the need for animal testing; however, a chemical structure is not necessarily related to toxicity. Therefore, in vitro studies were often used for read-across reliability refinement; however, their external validity has been hindered by the gap between in vitro and in vivo conditions. Thus, we developed a virtual DNA microarray, regression analysis–based inductive DNA microarray (RAID), which quantitatively predicts in vivo gene expression profiles based on the chemical structure and/or in vitro transcriptome data. For each gene, elastic-net models were constructed using chemical descriptors and in vitro transcriptome data to predict in vivo data from in vitro data (in vitro to in vivo extrapolation; IVIVE). In feature selection, useful genes for assessing the quantitative structure–activity relationship (QSAR) and IVIVE were identified. Predicted transcriptome data derived from the RAID system reflected the in vivo gene expression profiles of characteristic hepatotoxic substances. Moreover, gene ontology and pathway analysis indicated that nuclear receptor-mediated xenobiotic response and metabolic activation are related to these gene expressions. The identified IVIVE-related genes were associated with fatty acid, xenobiotic, and drug metabolisms, indicating that in vitro studies were effective in evaluating these key events. Furthermore, validation studies revealed that chemical substances associated with these key events could be detected as hepatotoxic biosimilar substances. These results indicated that the RAID system could represent an alternative screening test for a repeated-dose toxicity test and toxicogenomics analyses. Our technology provides a critical solution for IVIVE-based read-across by considering the mode of action and chemical structures.

Digital forensic investigation methodology for Storage Space: Based on the NIST digital forensic process.

For forensic examiners, investigating the RAID systems of servers has been challenging, as the examiners must reconstruct multiple high-capacity disks to identify digital evidence. Software-based RAID systems' use has been released for personal use, so examiners should consider RAID systems even when they investigate personal computers. Although there is a high probability that the software-based RAID will become a target of crime, there has been little research into digital forensic methodology for software-based RAID, as exemplified by Storage Space. In this paper, we introduce details about the structure of Storage Space found through reverse engineering. Storage Space was analyzed by applying the digital forensic process of NIST. We explain how to reconstruct a virtual disk configured using Storage Space and develop an automated tool to do so. To evaluate our study and the tool developed, we created an experimental scenario and describe in detail the forensic procedure and technical methods for the analysis of Storage Space. Our research can be used as the basis of forensic investigations for Storage Space.

Reliability of SSDs in Enterprise Storage Systems

This article presents the first large-scale field study of NAND-based SSDs in enterprise storage systems (in contrast to drives in distributed data center storage systems). The study is based on a very comprehensive set of field data, covering 1.6 million SSDs of a major storage vendor (NetApp). The drives comprise three different manufacturers, 18 different models, 12 different capacities, and all major flash technologies (SLC, cMLC, eMLC, 3D-TLC). The data allows us to study a large number of factors that were not studied in prior works, including the effect of firmware versions, the reliability of TLC NAND, and the correlations between drives within a RAID system. This article presents our analysis, along with a number of practical implications derived from it.

A stable storage in MANET: Replication or distributed storage

The notion of stable storage is very important in the area of fault tolerance. We are interested in the implementation of the concept of stable storage in mobile ad hoc environment. In this paper, we present the design and comparison of two solutions for implementing stable storage in mobile ad hoc networks (MANET) environment. One is based on the principle of data replication and the other on the distribution of the stable storage of a node on several nodes by inspiring of the technique of RAID systems used in hard disks. We exploit the creation of a structure in the form of a virtual tree in both contributions. A comparative study was performed between the two solutions through simulations in NS environment.

AIR: an approximate intelligent redistribution approach to accelerate RAID scaling

Nowadays, videos and images are becoming the predominant format of data storage, which take up more space than conventional plain texts. This rapid increment brings a high requirement on scalability in large data centers, where disk arrays (also referred to as “RAID”) are the main devices to store the numerous data. To improve the scalability of RAID systems, several scaling approaches are proposed to guarantee a uniform data distribution, such as decreasing migration I/Os and speeding up the scaling process. However, typical approaches are offline and ignore the impacts of concurrent application I/Os, which plays an important role on RAID scaling (i.e., data migration, data distribution, etc.). For example, an exact uniform data distribution among disks doesn’t mean an even I/O accesses to these disks. To address this problem, in this paper, we propose an approximate intelligent redistribution (AIR) approach to accelerate RAID scaling. The main idea of AIR is utilizing the dynamic data access patterns from concurrent application workloads, and providing an approximate data distribution to guarantee a uniform I/O accesses to various data disks. To achieve this goal, AIR utilizes the prevailing machine learning algorithms to identify hot data from application workloads, and gives an intelligent migration approach to minimize the data movements. By this way, AIR can sharply cut down the migration I/Os. To demonstrate the effectiveness of AIR approach, we conduct several simulations via Disksim. The results show that, compared to traditional RAID scaling approaches such as FastScale and GSR, AIR saves up to 99.3% I/O cost and reduces the data migration ratio by up to 95.8%, which speeds up the scaling process by a factor of up to 30.3X.

РОЗПОДІЛЕНЕ ЗБЕРЕЖЕННЯ ДАНИХ З ВИКОРИСТАННЯМ ЗАВАДОСТІЙКОГО КОДУВАННЯ

Проведено огляд теоретичних відомостей з теорії інформації та кодування, аналіз сучасних завадостійких кодів на предмет їх застосовності для збереження даних. Проаналізовано доцільність створення розподіленого сховища даних, основним механізмом збереження інформації якого є завадостійке кодування Ріда-Соломона.

A high-performance and endurable SSD cache for parity-based RAID

Solid-state drives (SSDs) have been widely used as caching tier for disk-based RAID systems to speed up data-intensive applications. However, traditional cache schemes fail to effectively boost the parity-based RAID storage systems (e.g., RAID-5/6), which have poor random write performance due to the small-write problem. What’s worse, intensive cache writes can wear out the SSD quickly, which causes performance degradation and cost increment. In this article, we present the design and implementation of KDD, an efficient SSD-based caching system which Keeps Data and Deltas in SSD. When write requests hit in the cache, KDD dispatches the data to the RAID storage without updating the parity blocks to mitigate the small write penalty, and compactly stores the compressed deltas in SSD to reduce the cache write traffic while guaranteeing reliability in case of disk failures. In addition, KDD organizes the metadata partition on SSD as a circular log to make the cache persistent with low overhead. We evaluate the performance of KDD via both simulations and prototype implementations. Experimental results show that KDD effectively reduces the small write penalty while extending the lifetime of the SSD-based cache by up to 6.85 times.

WB-RAIS: White-Box Redundant Array of Independent SSDs

Solid-state drives (SSDs) have been widely deployed in many platforms including consumer electronics, desktops and enterprise data centers due to their high performance and low power consumption. However, SSDs suffer from bit errors, and the bit error rate is time dependent since it increases as an SSD wears down. Traditional storage systems mainly use parity-based RAID to provide reliability guarantees by striping redundancy across multiple devices, but the effectiveness of traditional RAID schemes in SSDs remains debatable. Existing solutions are based on the block device SSDs, which used as faster HDD. But the characteristics of NAND flash memory and HDD are very different, Non-write-in place and background Garbage-collection have a negative impact on the real-time performance and reliability of the system. And almost all of the existing solutions are built on Black-Box SSD, which we cannot know the internal detail and data layout. As a result, they cannot take full advantage of flash memory features, reduce the parity updates costs and improve the system reliability. In this work, we proposed a new RAID system built on White-Box SSD, we call it WB-RAIS. For White-Box SSD, the FTL implement on the host side and it could be co-designed with the RAID controller. We exploit the characteristics of flash memory and build the strip mapping based on the physical block address. We also proposed a partial strip mechanism and smooth equipment replacement method. Experimental results show that WB-RAIS improves the write performance by an average of 20% and reduces the flash erase count 17–52% compared to Black-Box SSD RAID, and enhances the system reliability significantly.

Evaluation of ZFS as an efficient WLCG storage backend

A ZFS based software raid system was tested for performance against a hardware raid system providing storage based on the traditional Linux file systems XFS and EXT4. These tests were done for a healthy raid array as well as for a degraded raid array and during the rebuild of a raid array. It was found that ZFS performs better in almost all test scenarios. In addition, distinct features of ZFS were tested for WLCG data storage use, like compression and higher raid levels with triple redundancy information. The long term reliability was observed after converting all production storage servers at the Edinburgh WLCG Tier-2 site to ZFS, resulting in about 1.2PB of ZFS based storage at this site.

Performance Analysis of NFS Protocol Usage on VMware ESXi Datastore

Hypervisor virtualization that uses bare metal architecture allows to allocate and provide resources for each created virtual machines. Resources such as: CPU and memory, can be added or upgraded anytime to the host hardware (virtualization server) to be able to create more virtual machines. However, upgrading the hard drive size cannot be done anytime if there are already have data or virtual machine that has fully operated on the host hardware, related to the raid system and the establishment of hard drive partition. Upgrading hard drive size on virtualization server can be done by using NFS protocol on NAS server. VSphere ESXi able to use NFS protocol and store the virtual disk that is used by virtual machine as guest operating system on network storage besides using local hard drive (host hardware hard drive). When the virtual machine want to run the guest operating system, it will request to write/read virtual disk there is stored on NAS by using NFS protocol through the network. In this research, measurements has been taken on data communication performance due the usage of NFS as virtual machine’s datastore in addition to local hard drive usage on server’s device. Measurements were performed by sending various data size from client to server (virtual machine) and measure write/read speed on server’s cache memory and hard drive, and measure RTT (Round-trip Time) delay between client-server. The testing has been conducted on virtual machines that use local drive and NFS as virtual disk datastore.

PP: Popularity-based Proactive Data Recovery for HDFS RAID systems

Clustered storage systems as HDFS have become a popular platform for handling Big Data, susceptible to failures and data recovery whenever a failure is detected. However, existing recovery schemes in HDFS are passive, which affects the processing efficiency of MapReduce jobs and degrades the performance of Hadoop storage systems. In order to address this problem, this paper proposes a novel scheme called PP (Popularity-based Proactive Data Recovery), that significantly boost the recovery efficiency of HDFS RAID systems. PP tracks the popular data and immediately recovers the missing popular data when a node fails in Hadoop system, which effect and variation on the performance of MapReduce jobs is minimal. The lightweight prototype implementation of PP and extensive experiments demonstrate that, compared with Hadoop’s default locally-first scheduling and the degraded-first scheduling, PP significantly reduces the recovery time as well the execution time of MapReduce jobs concurrently.

On the Communication Cost of MDS Erasure Codes in Distributed Storage Systems

Distributed storage systems store some redundant data to keep the degree of availability of the stored data constant and also to increase the system's resistance against failures. This type of systems usually use pure replication or methods based on RAID systems as redundancy schemes. In this paper, we study the communication cost of a distributed data storage system using Maximum Distance Separable (MDS) erasure codes. Our focus is reduction of the cost of one-to-many communication used in data reconstruction/repair initialization and update operations. We propose the use of two different communication approaches on the area of distributed storage systems for the above operations; Steiner tree approach and multi-shortest path approach. We also analyse these two communication approaches empirically and theoretically. Our theoretical results indicate that Steiner tree approach has lower message usage, whereas, multi-shortest path approach has lower time usage for data reconstruction/repair initialization operations. On the other hand, Steiner tree approach has better message and time metrics for the data update process. Furthermore, our experimental results support these theoretical results. Thus, users can choose between the two approaches depending on their needs and priorities.

Does RAID Improve Lifetime of SSD Arrays?

Parity protection at the system level is typically employed to compose reliable storage systems. However, careful consideration is required when SSD-based systems employ parity protection. First, additional writes are required for parity updates. Second, parity consumes space on the device, which results in write amplification from less efficient garbage collection at higher space utilization. This article analyzes the effectiveness of SSD-based RAID and discusses the potential benefits and drawbacks in terms of reliability. A Markov model is presented to estimate the lifetime of SSD-based RAID systems in different environments. In a small array, our results show that parity protection provides benefit only with considerably low space utilizations and low data access rates. However, in a large system, RAID improves data lifetime even when we take write amplification into account.

Elastic-RAID: A New Architecture for Improved Availability of Parity-Based RAIDs by Elastic Mirroring

In this paper, we propose Elastic-RAID, a new RAID architecture to achieve high performance and high reliability for large-scale distributed and parallel storage systems. The key idea behind Elastic-RAID is to smartly utilize the free space existing in parity-based disk arrays to store additional mirroring data. This additional mirroring data redundancy, when strategically and judiciously activated and exploited in a RAID system, enables improved system I/O performance, fault tolerance and recovery. Depending on the amount of free space available and whether the emphasis is on performance or reliability, the elasticity in Elastic-RAID is manifested in how each design objective is achieved. For the performance objective, Elastic-RAID improves small-write performance by writing original and mirroring data synchronously and leaving the costly parity update in the background at a later idle/lightly-loaded time. For the reliability objective, at least two concurrent disk failures can be tolerated when Elastic-RAID is employed in a RAID5 system that has 50 percent or more free space. Higher reliability is provided for important data when free space is less than 50 percent. To achieve the design goal of elasticity, we introduce a novel data layout and addressing scheme. Our extensive trace-driven evaluations on an Elastic-RAID prototype in the typical configurations of RAID5 show that Elastic-RAID boosts the small-write performance in the normal operational state by at least 40 percent, improves the user I/O performance in the reconstruction state by at least 30 percent and shortens the recovery time by at least 40 percent.

Harnessing RAID mechanism for enhancement of data storage and security on cloud

As one of the most sought-after technologies in the world today, cloud computing finds a prominent place among researchers, service providers, hardware and software engineers, and consumers alike. Among the key services provided by cloud computing, the most widely used is storage on the cloud. To ensure a high degree of reliability and an almost constant state of availability, cloud storage systems rely on replication of data. Replicating data is not without its costs. In an attempt to mitigate costs of storage, designers have banked on erasure coding practices in lieu of data replication. This has resulted in development of Cloud RAID systems. An ideal Cloud RAID system strikes an optimum balance between performance, storage, and reliability. In addition to this, data security is of paramount interest. In this paper, we introduce an entirely new technique of storing data in cloud networks by file type classification. Combining RAID types with this, our paper proposes a model that is robust and can withstand instances of hard disk failures. Further, we discuss a methodology that is embedded in our proposed framework that supports user authentication for data storage and retrieval. Our Secure User Authenticated Cloud RAID model shields user data from prying eyes and even from unauthorized attempts by the cloud service provider our Secure User Authenticated Cloud RAID architecture.

A solid state drive architecture with memory card modules

Solid State Drive (SSD) for the consumer market may not require extreme high performance, but it does want high density at a low cost. Redundant Array of Inexpensive (or Independent) Disks (RAID) are built up by a group of independent disk drives, not inside a disk drive. This makes a RAID system not as inexpensive as expected in the beginning and in the end the system often becomes expensive, large in size and complexity. It is not well suited for consumer applications. This paper proposes a new structure, to build up a high density SSD in a RAID system by using SD or MMC/ eMMC modules instead of independent drives. A SSD controller chip with embedded RAID (eRAID) multiple level functions was designed and applied to verify this proposal. By using this controller and eMMC modules, a redundant array of independent modules (RAIM) is built up as an inexpensive single drive and proven to work. The result revealed that a RAIM can be a single SSD drive as well as a micro-RAID system. By utilizing RAIM SSD units a more sophisticated RAID system can be constructed at lower costs and greater performance in a much smaller configuration, which is more suitable as home cloud storage, etc.

Energy-aware and intelligent storage features for multimedia devices in smart classroom

With the recent big-data processing in multimedia devices becoming a popular application, a fast and energy efficient storage area network system for smart classroom is required. Traditional storage management system for smart classroom show low performance when small read and write operations are executed. This paper proposes a smart classroom storage management system (SCSMS) which consists of new adaptive chunking and XOR reference matrix based erasure coding techniques for multimedia devices with higher input/output performance and low energy consumption. The SCSI initiator is installed in multimedia devices such as smart TVs, smart phones and personal computers. The proposed adaptive chunking and exclusive-or (XOR) reference matrix-redundant array of inexpensive disks (XRM-RAID)are provided at a target server based on flash array storage, respectively. Adaptive chunking differs from traditional chunking in that it reduces the number of read and write operations by merging small files into a united chunk. XRM-RAID differs from existing RAID in that it reduces the number of XOR operations to generate parity data in the RAID system. This paper provides web based monitoring application of the proposed SCSMS. Experimental results show that the energy consumption of the proposed SCSMS is improved by 32 %, 42 % and 58 % compared to Huang et al., Kim et al. and Scott et al. with respect to file size and buffer size. In terms of the average write throughput, the proposed SCSMS has higher performance by 22 %, 32 % and 56 % compared to Huang et al., Kim et al. and Scott et al. with respect to file size and buffer size.

Performance Analysis of RAID in Different Workload

A performance evaluation model is built for the RAID system with queuing network. With MVA method we develop, validate and apply an analytic performance model for disks arrays configured as a RAID 5. The results show that the model can basically express the trend of the performance with different load.

<formula formulatype="inline"><tex Notation="TeX">${\rm S}^{2}$</tex></formula>-RAID: Parallel RAID Architecture for Fast Data Recovery

As disk volume grows rapidly with terabyte disk becoming a norm, RAID reconstruction process in case of a failure takes prohibitively long time. This paper presents a new RAID architecture, S <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -RAID, allowing the disk array to reconstruct very quickly in case of a disk failure. The idea is to form skewed sub-arrays in the RAID structure so that reconstruction can be done in parallel dramatically speeding up data reconstruction process and hence minimizing the chance of data loss. We analyse the data recovery ability of this architecture and show its good scalability. A prototype S <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -RAID system has been built and implemented in the Linux operating system for the purpose of evaluating its performance potential. Real world I/O traces including SPC, Microsoft, and a collection of a production environment have been used to measure the performance of S <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -RAID as compared to existing baseline software RAID5, Parity Declustering, and RAID50. Experimental results show that our new S <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -RAID speeds up data reconstruction time by a factor 2 to 4 compared to the traditional RAID. Meanwhile, S <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -RAID keeps comparable production performance to that of the baseline RAID layouts while online RAID reconstruction is in progress.