RAID-PIR

Private Information Retrieval (PIR) protocols, which allow the client to obtain data from servers without revealing its request, have many applications such as anonymous communication, media streaming, blockchain security, advertisement, etc. Multi-server PIR protocols, where the database is replicated among the non-colluding servers, provide high efficiency in the information-theoretic setting. Beimel et al. in CCC 12’ (further referred to as BIKO) put forward a paradigm for constructing multi-server PIR, capturing several previous constructions for servers, as well as improving the best-known share complexity for 3-server PIR. A key component there is a share conversion scheme from corresponding linear three-party secret sharing schemes with respect to a certain type of “modified universal” relation. In a useful particular instantiation of the paradigm, they used a share conversion from -CNF over to three-additive sharing over for primes where and , and the relation is modified universal relation . They reduced the question of the existence of the share conversion for a triple to the (in)solvability of a certain linear system over , and provided an efficient (in ) construction of such a sharing scheme. Unfortunately, the size of the system is which entails the infeasibility of a direct solution for big m’s in practice. Paskin-Cherniavsky and Schmerler in 2019 proved the existence of the conversion for the case of odd , when , obtaining in this way infinitely many parameters for which the conversion exists, but also for infinitely many of them it remained open. In this work, using some algebraic techniques from the work of Paskin-Cherniavsky and Schmerler, we prove the existence of the conversion for even m’s in case (we computed in this case) and the absence of the conversion for even m’s in case . This does not improve the concrete efficiency of 3-server PIR; however, our result is promising in a broader context of constructing PIR through composition techniques with servers, using the relation where m has more than two prime divisors. Another our suggestion about 3-server PIR is that it’s possible to achieve a shorter server’s response using the relation for extended . By computer search, in BIKO framework we found several such sets for small m’s which result in share conversion from -CNF over to 3-additive secret sharing over , where is several times less than , which implies several times shorter server’s response. We also suggest that such extended sets can result in better PIR due to the potential existence of matching vector families with the higher Vapnik-Chervonenkis dimension.

Private information retrieval (PIR) protocols allow a user to retrieve a data item from a database without revealing any information about the identity of the item being retrieved. Specifically, in information-theoretic k-server PIR, the database is replicated among k non-communicating servers, and each server learns nothing about the item retrieved by the user. The cost of PIR protocols is usually measured in terms of their communication complexity, which is the total number of bits exchanged between the user and the servers. However, another important cost parameter is the storage overhead, which is the ratio between the total number of bits stored on all the servers and the number of bits in the database. Since single-server information-theoretic PIR is impossible, the storage overhead of all existing PIR protocols is at least 2 (or k, in the case of k-server PIR). In this work, we show that information-theoretic PIR can be achieved with storage overhead arbitrarily close to the optimal value of 1, without sacrificing the communication complexity. Specifically, we prove that all known k-server PIR protocols can be efficiently emulated, while preserving both privacy and communication complexity but significantly reducing the storage overhead. To this end, we distribute the n bits of the database among s + r servers, each storing n/s coded bits (rather than replicas). Notably, our coding scheme remains the same, regardless of the specific k-server PIR protocol being emulated. For every fixed k, the resulting storage overhead (s +r)/s approaches 1 as s grows; explicitly we have equation. Moreover, in the special case k = 2, the storage overhead is only 1 + 1/s. In order to achieve these results, we introduce and study a new kind of binary linear codes, called here k-server PIR codes. Finally, we show how such codes can be constructed from multidimensional cubic, from Steiner systems, and from one-step majority-logic decodable codes.

Private information retrieval (PIR) protocols allow a user to retrieve a data item from a database while hiding the identity of the item being retrieved. Specifically, in information-theoretic, k-server PIR protocols the database is replicated among k servers, and each server learns nothing about the item the user retrieves. The cost of such protocols is measured by the communication complexity of retrieving one out of n bits of data. For any fixed k, the complexity of the best protocols prior to our work was O(n/sup 1/2k-1/). Since then several methods were developed in an attempt to beat this bound, but all these methods yielded the same asymptotic bound. In this paper, this barrier is finally broken and the complexity of information-theoretic k-server PIR is improved to n/sup O(log log k/k log k)/. The new PIR protocols can also be used to construct k-query binary locally decodable codes of length exp(n/sup O(log log k/k log k)/), compared to exp(n/sup 1/k-1/) in previous constructions. The improvements presented in this paper apply even for small values of k: the PIR protocols are more efficient than previous ones for every k/spl ges/3, and the locally decodable codes are shorter for every k/spl ges/4.

Customer requirements have guided the evolution and implementation of software and hardware computer data storage technologies. The concept of RAID originated with a group of researchers at the University of California at Berkeley (UCB). They were investigating the use of an array of small capacity, inexpensive personal computer direct access storage devices (DASD) managed by a special type of a controller, as an alternative to the single large expensive disk (SLED) subsystems more common on mainframe computers. The disk arrays can be configured differently to provide different levels of operational capabilities, each providing special advantages in reliability and data availability, speed and economy. Different configurations are referred to as different levels of RAID. Berkeley originally defined a basic set of RAID levels ranging from RAID, level 0 (RAID 0) through RAID, level 5 (RAID 5). The RAID technology vendors have since extended the RAID level domain by defining RAID 6 and beyond to accommodate additional functionality. Each RAID type has shown itself to be suitable for certain applications. The projected reduction in storage costs and facilities, $/GB and ft2/GB respectively, using the present RAID technology and its projected evolution are phenomenal.

Distributed i>redundant array of inexpensive disks (RAID) is often embedded in a cluster architecture. In a centralized RAID subsystem, the false sharing problem does not exist, because the disk array allows only mutually exclusive access by one user at a time. However, the problem does exist in a distributed RAID architecture, because multiple accesses may occur simultaneously in a distributed environment. This problem will seriously limit the effectiveness of collective I/O operations in network-based, cluster computing. Traditional accesses to disks in a RAID are done at block level. The block granularity is large, say 32 KB, often resulting in false sharing among fragments in the block. The false sharing problem becomes worse when the block size or the stripe unit becomes too large. To solve this problem, we propose an adaptive sector grouping approach to accessing a distributed RAID. Each sector has a fine grain of 512 B. Multiple sectors are grouped together to match with the data block size. The grouped sector has a variable size that can be adaptively adjusted by software. Benchmark experiments reveal the positive effects of this adaptive access scheme on the performance of a RAID. Our scheme can reduce the collective I/O access time without increasing the buffer size. Both theoretical analysis and experimental results demonstrate the performance gain in using grouped sectors for fast access of distributed RAID.

Outsourcing database as service instead of using in-house database management is a new trend emerging in a computing industry; there has been growing interest in outsourcing database services in both the commercial world and the research community. In this paper, we present analysis of non-concurrent model of fast single-database Private Information Retrieval (PIR) scheme for maintaining data privacy with data confidentiality using encryption algorithm like AES for Outsourced Database Service (ODBS) Model. In this model encryption method maintains data confidentiality and a utility that help to create PIR reply which maintains data privacy. In PIR Scheme data privacy is achieved by adding noise data into the result of a typical query which is called as PIR reply. Single-database PIR schemes are generally not practical because of its expensiveness from computational point of view. Here we propose a model that suggests the use of General-Purpose computation using Graphic Processing Units (GPGPU) commodity to process such type of computationally intensive operations. This model will help to achieve practical implementation of single-database PIR scheme which uses encryption algorithm to maintain data confidentiality as secondary goal and it serves to create database reply to maintain data privacy as primary goal. This paper shows some real time results that proves need of concurrency in PIR algorithms. It also describes the use of lattice based single-database PIR protocol with GPGPU as a processing unit to achieve high speed-up and hence, the performance of the system.

There has been much recent interest in private information retrieval (PIR) in models where a database is stored across several servers using coding techniques from distributed storage, rather than being a simply replicated. In particular, a recent breakthrough result of Fazelli, Vardy, and Yaakobi introduces the notion of a PIR code and a PIR array code, and uses this notion to produce efficient PIR protocols. In this paper, we are interested in designing PIR array codes. We consider the case when we have m servers, with each server storing a fraction (1/s) of the bits of the database; here s is a fixed rational number with s > 1. A PIR array code with the k-FIR property enables a k-server PIR protocol (with k ≤ m) to be emulated on m servers, with the overall storage requirements of the protocol being reduced. The communication complexity of a PIR protocol reduces as k grows, so the virtual server rate, defined to be k/m, is an important parameter. We study the maximum virtual server rate of a PIR array code with the k-PIR property. We present upper bounds on the achievable virtual server rate, some constructions, and ideas how to obtain the PIR array codes with the highest possible virtual server rate. In particular, we present constructions that asymptotically meet our upper bounds and the exact largest virtual server rate is obtained when 1 <; s ≤ 2. A k-PIR code (and similarly a k-PIR array code) is also a locally repairable code with symbol availability k-1. Such a code ensures k parallel reads for each information symbol. So the virtual server rate is very closely related to the symbol availability of the code when used as a locally repairable code. The results of this paper are discussed also in this context where subspace codes also have an important role.

The storage and bandwidth requirements of digital video and audio exceed those that can be supported by conventional file servers. Despite the emergence of new compression algorithms capable of providing extremely high compression ratios, there is still a challenge to provide optimised storage services capable of storing 1000s of hours of multimedia data and providing simultaneous access to hundreds and potentially thousands of clients. A number of prototype multimedia storage devices have been designed and built to address the real-time demands of digital video and audio1,9. These systems use RAID (Redundant Arrays of Inexpensive Disks) technology to increase the bandwidth and storage capacities of single disks. Unfortunately, RAID is non-scalable10 (i.e. disks cannot be incrementally added to provide higher bandwidth and storage facilities) and can prove to be a bottleneck in the system. This server bottleneck only becomes significant when the aggregate disk bandwidth of RAID increases beyond either the network interface or the server CPU / bus speed. Once this occurs the available storage and bandwidth can only be increased by introducing more RAID servers and introducing a load balancing policy where client requests can be shared across multiple server instances. This paper describes a Scalable Multimedia Storage Architecture (SMSA) that supports wide area storage, storage server scalability allowing the addition of extra storage nodes, and maximised available data streams through the use of the load balancing techniques of network striping / file replication. It also allows for the storage of multi-resolution data produced by scalable compression techniques to match the Quality of Service requirements of heterogeneous clients.

We present SlicedPIR, a distributed Private Information Retrieval (PIR) protocol. SlicedPIR efficiently alleviates the server's compute bottleneck by offloading its load across multiple untrusted client machines. In contrast to prior work, SlicedPIR induces only a modest network overhead when the server offloads its work. It achieves those communication savings by exploiting the polynomial encoding of homomorphic encryption schemes typically used in PIR protocols. This encoding lets the server make novel use of the Number Theoretic Transform (NTT) to distribute points on the polynomials as ''slices'' of its data rather than the polynomials themselves. Using NTT allows the clients to process recursive PIR queries on their slices and return a succinct result to the server. The server efficiently verifies the clients' results by leveraging the Schwartz-Zippel lemma, which we adapt to the PIR use case. We show how to integrate SlicedPIR into a private messaging system, where clients write messages to the server's database and then use PIR to secretly query for messages from their friends. We implement a prototype of SlicedPIR and run experiments to show that it scales well with the number of clients and database size. Concretely, SlicedPIR achieves better performance and cuts network usage by over 95% compared to the state-of-the-art.

RAID (Redundant Array of Inexpensive Disks) are widely used in storage servers. Level-5 RAID is one of the most popular RAID architectures. Numerical analysis of exact Markovian dependability models of level-5 RAID architectures with orthogonal organization is unfeasible for many realistic model parameters due to the size of the resulting state space. In this paper we develop approximate dependability models for a level-5 RAID architecture with orthogonal organization which have small state spaces. We consider two measures: the steady-state unavailability and the unreliability. The models encompass disk hot spares and imperfect disk reconstruction. Using bounding techniques we analyze the accuracy of the models and show that the models are extremely accurate.

Database outsourcing as a service is a new trend emerging in the computing industry instead of managing database in-house. This introduces several security issues related to database. One of the important security requirements is privacy. A Private Information Retrieval protocol (PIR) allows user to retrieve an element from the database in such way that identity of that element is not get revealed by database server. In this project work, we present the optimized lattice based PIR schema. This proposed schema is based on use of different techniques like General Purpose Graphics Processing Unit (GPGPU) and cache like technology to reduce accessibility. The latest proposed PIR scheme deal with user privacy, use of GPGPU but left to focus on data privacy, data confidentiality and accessibility cost. In our approach our system focusing on issues like user privacy, data confidentiality and accessibility cost by using cache and computational overhead by using GPGPU. Thus searching time of proposed PIR protocol is minimized to number of records in the cache. Thus our proposed design improves the overall performance of PIR protocol.

This paper is a summary and evaluation of redundant array of independent disks (also called redundant array of inexpensive disks before) that was proposed years ago. Recently more information is produced every year, and the demand of data storage is increasing exponentially due to Moore's Law. So, it's much more common to group a dozen of hard disk drives together, to achieve better performance or to achieve better data safety. Firstly, the redundant array of independent disks aims to solve the data safety/data in-out performance problems, and multiple ways are proposed including Level 0 to solve the performance problem sacrificing system stability and data safety and Level 1 aims to achieve better stability but using only 50% (or less) of the data capacity. The development of redundant array of independent disks tends to be merged and have more functions in one single system of redundant array of inexpensive disks.

Redundant Arrays of Inexpensive Disks (RAID) is a popular technique used to improve the reliability and performance of secondary storage. Of various levels of RAID discussed, RAID1 and RAID5 have become more popular. Mirroring or RAID1 maintains multiple copies of the data, generally provides best performance and is easier to configure. Rotating parity scheme or RAID5 is the least expensive RAID scheme with good large update performance. It suffers from poor small update performance and performance drops sharply when a diskfails and the array enters degraded mode. Configuring RAID5 is more involved. This paper presents the design and implementation of a host-based driver for a multi-tier RAID storage system, currently with 2 tiers: a small RAID1 tier and a larger RAID5 tier. Based on access patterns, the driver automatically migrates frequently accessed data to RAID1 while demoting not so frequently accessed data to RAID5. The prototype provides reliable persistence semantics for data migration between the tiers using ordered updates. Mechanisms are separated from policies through an API so that any desired policy can be implemented in trusted user processes. Finally, we present comparison of the performance of our system with comparable systems using striping and RAID5.

HDDs are like the bread in a peanut butter and jelly sandwich—sort of an unexciting piece of hardware necessary to hold the “software.” They are simply a means to an end. HDD reliability, however, has always been a significant weak link, perhaps the weak link, in data storage. In the late 1980s people recognized that HDD reliability was inadequate for large data storage systems so redundancy was added at the system level with some brilliant software algorithms, and RAID (redundant array of inexpensive disks) became a reality. RAID moved the reliability requirements from the HDD itself to the system of data disks. Commercial implementations of RAID range from n+1 configurations (mirroring) to the more common RAID-4 and RAID-5, and recently to RAID-6, the n+2 configuration that increases storage system reliability using two redundant disks (dual parity). Additionally, reliability at the RAID group level has been favorably enhanced because HDD reliability has been improving as well.

The authors discuss various types of RAIDs (redundant arrays of inexpensive disks), a cost-effective option to meet the challenge of exponential growth in the processor and memory speeds. They argue that the size reduction of personal-computer (PC) disks is the key to the success of disk arrays. While large arrays of mainframe processors are possible, it is certainly easier to construct an array from the same number of microprocessors (or PC drives). With advantages in cost-performance, reliability, power consumption, and floor space, the authors expect RAIDs to replace large drives in future I/O systems. >