Read Requests Research Articles

“Must Be Clean, Safe and Discreet”

Abstract On digital hook-up apps for same-sex attracted men, it is common to read requests for “discretion” from “discreet” men expecting others be the same. Such discretionary language is not new but has evolved and shifted as it became coded into the affordances of hook-up apps. We argue to be discreet is not necessarily to be “closeted” or to be a “MSM” (man who has sex with men). Drawing on our research of men who engage with online same-sex hook-ups, we consider the context of discretionary language used. We discuss how this illustrates the paradox of discretionary language, where requests for discretion typically imply the requester is seeking to act indiscreetly in some fashion.

Hybrid fault tolerance in distributed in-memory storage systems

An in-memory storage system provides submillisecond latency and improves the concurrency of user applications by caching data into memory from external storage. Fault tolerance of in-memory storage systems is essential, as the loss of cached data requires access to data from external storage, which evidently increases the response latency. Typically, replication and erasure code (EC) are two fault-tolerant schemes that pose different trade-offs between access performance and storage usage. To help make the best performance and space trade-off, we design ElasticMem, a hybrid fault-tolerant distributed in-memory storage system that supports elastic redundancy transition to dynamically change the fault-tolerant scheme. ElasticMem exploits a novel EC-oriented replication (EOR) that carefully designs the data placement of replication according to the future data layout of EC to enhance the I/O efficiency of redundancy transition. ElasticMem solves the consistency problem caused by concurrent data accesses via a lightweight table-based scheme combined with data bypassing. It detects corelated read and write requests and serves subsequent read requests with local data. We implement a prototype that realizes ElasticMem based on Memcached. Experiments show that ElasticMem remarkably reduces the time of redundancy transition, the overall latency of corelated concurrent data accesses, and the latency of single data access among them.

ЧИТАЦЬКІ ІНТЕРЕСИ І ЇХ ВПЛИВ НА ФОРМУВАННЯ ЧИТАЦЬКОЇ САМОСТІЙНОСТІ В КОНТЕКСТІ ІДЕЙ ІВАНА ОГІЄНКА

The article considers the problem of the infl uence of reading interests of primary school pupils on the formation of reading autonomy. The psychological and pedagogi-cal literature was analysed from the point of view of methods of forming interest in scientifi c and informative literature. The role of cognitive interest in the formation of reading autonomy is clarifi ed: the nature, indicators, and conditions of the formation of interest in books in the context of Ivan Ohiienko’s views are found out.The data of the conducted research are presented, which demonstrated that read-ing is far from the fi rst place among children of primary school age. Among the pri-orities are computer games, watching television programs, walks and games in the fresh air with friends, and only then ‒ reading books. From the 1st to the 4th grade, the interest in reading among primary school pupils is gradually lost. The circle of readers who are motivated to read specifi c literature and who has a lack of elementary bibliographic literacy is defi ned.The results of the analysis of reading forms and requests of primary school pupils regarding topics and authors are presented; priorities in the literature are defi ned.The results of a formative experiment are adduced, during which there was used literature, grouping and arranging it according to thematic direction and in accordance with the identifi cation of reading interests of primary school pupils. The advantages of the science and art book as a means of learning the laws of nature are determined. Emphasis is placed on the need for primary school pupils to read works from diff er-ent sections of informative literature, since popular science and science fi ction works complement each other: science fi ction causes cognitive interest, which can be more satisfi ed by reading non-fi ction books, while the ability to use a non-fi ction book depends on the level of understanding of science fi ction. The literary works of these subsections meet the various requests of pupil readers at diff erent levels of their gen-eral education, depending on their age, internal state of mind and reading tastes. Not everyone understands the diff erence between non-fi ction and fi ction, and the choice of eff ective methods of working with the literary work depends on this.The role of the family in the formation of spiritual values in the context of I. Ohiienko’s views and reading interests and reading autonomy of primary school pupils is clarifi ed

TIME OPTIMIZATION OF PROCESS OF DATA CONSISTENCY IN NOSQL

It is emphasized that the performance of a distributed information system depends on many factors, including the size and structure of the database, the hardware used, the number of replicas and their geographical location. A conclusion was made about the perspective of the concept of non-relational NoSQL databases and it was concluded that it was proposed for efficient storage and provision of quick access to large volumes of information, the so-called Big Data, which cannot be achieved using traditional relational database management systems. The essence of the concept of “NoSQL database” is revealed and the currently existing difficulties in using large systems are named. In NoSQL databases, multiple replication (copying) of a record is used to ensure high fault tolerance. But there is a significant drawback for them, because these systems do not support the mode of conducting transactions and blocking, so there is a problem of data reconciliation. It is emphasized that NoSQL databases mainly use two methods of placing and updating the time of the data consistency process in NoSQL: according to the principle of “master-slave” and “ring”. A model of strong data reconciliation in NoSQL is described and an example of time optimization for the healthcare system is considered. It has been established that even with large values of the intensity of receiving requests for reading λ, the waiting time does not exceed 3 ms. However, when performing analytical queries, this time can increase, so with large N and high intensity of incoming read requests, this time can reach 7 ms.

SPANoF: A Scalable and Performant Architecture for NVMeoF-Based Storage Disaggregation with Limited Network Resources

NVMe-over-Fabrics (NVMeoF) is expected to have high-performance and be highly scalable for disaggregating NVMe SSDs to High-Speed Network (HSN)-attached storage servers, thus the aggregated NVMe SSDs in storage servers can be elastically allocated to remote host servers for better utilization. However, due to the well-known connection scalability issue of RDMA NICs (RNICs), RDMA-enabled HSN can only provide a limited scale of performant Queue Pairs (QPs) for NVMeoF I/O queues to transfer capsule and data between the storage server and remote host servers. However, in current NVMeoF implementations, multiplexing multiple NVMeoF I/O queues onto a single RNIC QP is not supported yet. In this paper, we investigate how NVMeoF capsule and data transfers are performed efficiently over HSN with a limited number of RNIC QPs, and propose SPANoF, a Scalable and Performant Architecture for NVMe-over-Fabrics. SPANoF dissolves the intrinsic one-to-one mapping relationship between NVMeoF I/O queues and RNIC QPs, allocates a dedicated send-list for each NVMeoF I/O queue rather than for each RNIC QP, transfers NVMeoF capsules and data in send-lists with a QP-centric manner to remove lock-contention overhead, and polls for transfer completion notifications to remove interrupt-caused context switch overhead. We implemented SPANoF in the Linux kernel and evaluated it by the FIO benchmarks. Our experimental results demonstrate that SPANoF can avoid the performance collapses for commercial RNICs with a limited number of performant QPs and avoid the system crash for domain-specific RNICs with only limited-scale available QPs. Compared with the native NVMeoF implementation in Linux kernel, SPANoF can saturate an RNIC of the storage server with only three RNIC QPs of the remote host server. Compared with lock-based QP-sharing mechanisms, SPANoF improves bandwidth by up to 1.55× under 64 KB sequential write requests, improves throughput by up to 4.18× and reduces the average latency by 28.31% under 4 KB random read requests.

Hospital-wide survey of clinical experience with artificial intelligence applied to daily chest radiographs.

To assess experience with and perceptions of clinical application of artificial intelligence (AI) to chest radiographs among doctors in a single hospital. A hospital-wide online survey of the use of commercially available AI-based lesion detection software for chest radiographs was conducted with all clinicians and radiologists at our hospital in this prospective study. In our hospital, version 2 of the abovementioned software was utilized from March 2020 to February 2021 and could detect three types of lesions. Version 3 was utilized for chest radiographs by detecting nine types of lesions from March 2021. The participants of this survey answered questions on their own experience using AI-based software in daily practice. The questionnaires were composed of single choice, multiple choices, and scale bar questions. Answers were analyzed according to the clinicians and radiologists using paired t-test and the Wilcoxon rank-sum test. One hundred twenty-three doctors answered the survey, and 74% completed all questions. The proportion of individuals who utilized AI was higher among radiologists than clinicians (82.5% vs. 45.9%, p = 0.008). AI was perceived as being the most useful in the emergency room, and pneumothorax was considered the most valuable finding. Approximately 21% of clinicians and 16% of radiologists changed their own reading results after referring to AI, and trust levels for AI were 64.9% and 66.5%, respectively. Participants thought AI helped reduce reading times and reading requests. They answered that AI helped increase diagnostic accuracy and were more positive about AI after actual usage. Actual adaptation of AI for daily chest radiographs received overall positive feedback from clinicians and radiologists in this hospital-wide survey. Participating doctors preferred to use AI and regarded it more favorably after actual working with the AI-based software in daily clinical practice.

Design of Resilient Supervisory Control for Autonomous Connected Vehicles Approaching Unsignalized Intersection in presence of Cyber-Attacks

The aim of this paper is to ensure safety in a distributed dynamical system, modeled as a Discrete Events Systems (DES), whose feedback control is compromised by a malicious attacker hijacking the system communication channel, being able to insert or remove sensor reading and/or actuation requests. Our focus is autonomous connected vehicle applications and the synthesis of a supervisor that is robust against a large class attacks. Specifically, we model DES supervisors for managing the interactions among self-driving cars when negotiating access to a traffic junction in the presence of an attacker who can manipulate the outputs from the sensors of the system before they can reach the supervisory controller itself. We propose different supervisor solutions to assess the resilience of the intersection crossing and we disclose the best suitable one for the appraised automotive application, as well as its effectiveness.

Degraded Mode-benefited I/O Scheduling to Ensure I/O Responsiveness in RAID-enabled SSDs

RAID-enabled SSDs commonly have unbalanced I/O workloads on their components (e.g., SSD channels), as the data/parity chunks in the same stripe may have varied access frequency, which greatly impacts I/O responsiveness. This article proposes a I/O scheduling scheme by resorting to the degraded read mode and the read-modify-write mode to reduce the long-tail latency of I/O requests in RAID-enabled SSDs. The basic idea is to avoid scheduling read or update requests to the heavily congested but targeted RAID components. Such requests are satisfied by accessing other relevant RAID components by certain XOR computations (we call the degraded modes ). Specially, we build a queuing overhead assessment model on the top of factors of data redundancy and the current blocked I/O traffics on SSD channels to precisely dispatch incoming I/O requests to be fulfilled with the degraded mode or not. The trace-driven experiments illustrate that the proposed scheme can reduce the long-tail latency of read requests by 23.1% on average at the 99.99th percentile, in contrast to state-of-the-art scheduling methods.

EDC: An Elastic Data Cache to Optimizing the I/O Performance in Deduplicated SSDs

Data deduplication is widely deployed in solid-state drives (SSDs) to improve the storage space utilization and alleviate the endurance issue. However, deduplication increases the degree of fragmentation and the access contention, significantly hurting the system performance. First, the fragmentation at the storage medium level in SSD is closely related to the internal parallelism, and the degree of fragmentation increases as the degree of the parallelism decreases. Deduplication removes the duplicate parts of the write sequences, decreasing the read parallelism. Thus, the degree of fragmentation is increased, eventually degrading the read performance. Second, the uneven distribution of the highly referenced data increases the access contention. This increased access contention prolongs the queueing time, further degrading the system performance. Motivated by our observations, we propose an elastic data cache (EDC) to improve the I/O performance in the deduplicated SSD. EDC redesigns the built-in DRAM-based data cache, tracks the popular and highly-referenced data, and maintains them in the cache. To fulfill the novel data cache, EDC changes the request process. The read requests that access the fragments in the flash memory are mostly performed in the fast-speed data cache, alleviating the negative impact of fragmentation on the read performance. The reduced read accesses to the flash memory also ease the access contention, which improves the system performance significantly. Extensive experimental results validate the efficiency of EDC, showing that it effectively improves the read performance and the write performance by up to 79% and 85% on average, respectively, in the deduplicated SSD.

An Exact Algorithm for the Linear Tape Scheduling Problem

Magnetic tapes are often considered as an outdated storage technology, yet they are still used to store huge amounts of data. Their main interests are a large capacity and a low price per gigabyte, which come at the cost of a much larger file access time than on disks. With tapes, finding the right ordering of multiple file accesses is thus key to performance. Moving the reading head back and forth along a kilometer long tape has a non-negligible cost and unnecessary movements thus have to be avoided. However, the optimization of tape request ordering has rarely been studied in the scheduling literature, much less than I/O scheduling on disks. For instance, minimizing the average service time for several read requests on a linear tape remains an open question. Therefore, in this paper, we aim at improving the quality of service experienced by users of tape storage systems, and not only the peak performance of such systems. To this end, we propose a reasonable polynomial-time exact algorithm while this problem and simpler variants have been conjectured NP-hard. We also refine the proposed model by considering U-turn penalty costs accounting for inherent mechanical accelerations. Then, we propose a low-cost variant of our optimal algorithm by restricting the solution space, yet still yielding an accurate suboptimal solution. Finally, we compare our algorithms to existing solutions from the literature on logs of the mass storage management system of a major datacenter. This allows us to assess the quality of previous solutions and the improvement achieved by our low-cost algorithm. Aiming for reproducibility, we make available the complete implementation of the algorithms used in our evaluation, alongside the dataset of tape requests that is, to the best of our knowledge, the first of its kind to be publicly released.

Accelerating Reads With In-Network Consistency-Aware Load Balancing

We present FLAIR, a novel approach for accelerating read operations in leader-based consensus protocols. FLAIR leverages the capabilities of the new generation of programmable switches to serve reads from follower replicas without compromising consistency. The core of the new approach is a packet-processing pipeline that can track client requests and system replies, identify consistent replicas, and at line speed, forward read requests to replicas that can serve the read without sacrificing linearizability. An additional benefit of FLAIR is that it facilitates devising novel consistency-aware load balancing techniques. Following the new approach, we designed FlairKV, a key-value store atop Raft. FlairKV implements the processing pipeline using the P4 programming language. We evaluate the benefits of the proposed approach and compare it to previous approaches using a cluster with a Barefoot Tofino switch. Our evaluation indicates that, compared to state-of-the-art alternatives, the proposed approach can bring significant performance gains: up to 42% higher throughput and 35–97% lower latency for most workloads. Furthermore, our evaluation shows that our novel load balancing techniques can cope with heterogeneous load and hardware to achieve higher performance, and that FLAIR can scale to support large data sets and clusters.

Multidirectional Replication for Supporting Strong Consistency, Low Latency, and High Throughput

Many replication protocols, which can be used in various distributed applications such as distributed databases, collaborative applications, and distributed agenda, sacrifice strong consistency to achieve lower latency and higher throughput. This paper describes the design, specification, implementation, and evaluation of Unidirectional and Multidirectional Replication, which challenge this inflexible tradeoff. By propagating the resulting states parallelly, as in Primary-Backup Replication, but with fewer messages, while having a head that processes write requests and a tail that processes read requests, as in Chain Replication, Unidirectional Replication improves the latency and throughput of the two protocols without compromising strong consistency. To improve the utilization of computing and communication resources of Unidirectional Replication, Multidirectional Replication divides objects into several logical shards and runs an instance of Unidirectional Replication on each logical shard. We have accomplished the proposed protocols in three steps: (1) merging Primary-Backup Replication and Chain Replication into Unidirectional Replication; (2) merging Unidirectional Replication and logical sharding into Multidirectional Replication; and (3) implementation and evaluation. Empirical results show that, compared to Primary-Backup Replication, when handling read requests with write-read conflicts, Unidirectional Replication shows an improvement of roughly 66% in latency; compared to Chain Replication, when handling write requests with basic settings, Unidirectional Replication shows an improvement of roughly 59% in throughput; and compared to Unidirectional Replication, Multidirectional Replication shows an improvement of 150% in the number of clients that it can handle.

HUBUNGAN MINTA BACA DENGAN KEMAMPUAN MENGIDENTIFIKASI UNSUR-UNSUR PEMBANGUN TEKS PUISI KELAS VII SMP NEGERI 40 PADANG

This study aims to describe students' interest in reading, describe the ability to identify the building blocks of students' poetry texts, and to describe the relationship between reading requests and the ability to identify elements of poetry texts for class VII SMP Negeri 40 Padang. In this study, there were 2 classes as the research sample for class VII.1 as many as 29 students and another class as a test class for class VII.2 questionnaires with 27 students. The sampling technique was carried out using the purposive sampling technique. The instruments used in this research are questionnaires and objective tests. The results of this study are three things. First, the reading interest of class VII students of SMP Negeri 40 Padang obtained anaverage score of 74.24 in the range of 66-75% on a scale of 10, with more than adequate qualifications (LdC). Second, the ability to identify the elements of poetry building for seventh grade students of SMP Negeri 40 Padang obtained an average score of 82,34 in the range of values of 75-85% on a scale of 10, with good qualifications (B). Third, there is a significant relationship between reading interest and the ability to identify elements of poetry building for students of VII SMP Negeri 40 Padang. This shows that reading interest affects students in identifying the building blocks of poetry. This can be seen from the test results which prove that tcount > from ttable, namely 5.40 > 1.70.

Read Refresh Scheduling and Data Reallocation against Read Disturb in SSDs

Read disturb is a circuit-level noise in flash-based Solid-State Drives (SSDs), induced by intensive read requests, which may result in unexpected read errors. The approach of read refresh (RR) is commonly adopted to mitigate its negative effects by unconditionally migrating all valid data pages in the RR block to another new block. However, routine RR operations greatly impact the I/O responsiveness of SSDs, because the processing on normal I/O requests must be blocked at the same time. To further reduce the negative effects of read refresh, this article proposes a read refresh scheduling and data reallocation method to deal with two primary issues with respect to an RR operation, including where to place data pages and when to trigger page migrations. Specifically, we first construct a data reallocation model to match the data pages in the RR block and the destination blocks for addressing the issue of where to place the data. The model considers not only the read hotness of pages in the RR block, but also the accumulated read counts of the destination blocks. Moreover, for addressing the issue of when to trigger data migrations, we build a timing decision model to determine the time points for completing page migrations by considering the factors of the intensity of I/Os and the disturb situation on the RR block. Through a series of simulation experiments based on several realistic disk traces, we illustrate that the proposed RR scheduling and data reallocation mechanism can noticeably reduce the read errors by more than 10.3% , on average, and the long-tail latency by between 43.9% and 64.0% at the 99.99th percentile, in contrast to state-of-the-art methods.

An Efficient Ensemble Architecture for Privacy and Security of Electronic Medical Records

Electronic medical records, one of the sensitive data, are stored in public or private cloud service providers. Cloud systems provide security with firewall and intrusion detection systems, and these systems ensure privacy with access control and end-to-end encryption. However, while sending data to the cloud system, attackers can capture the data with the help of Man in the Middle attacks and vulnerabilities of the storage systems. In the middleware architecture proposed in this study, access control protocol, key distributor and end-to-end hybrid encryption which are based on user roles were innovatively used to overcome security issues in data transmission. In this system, writing and updating requests are encrypted asymmetrically, and reading requests were encrypted symmetrically. This solution distinguishes the proposed method from previous studies. According to this solution the operating performance of the system is increased. In addition, the attacker cannot see the actual data in a cyber-attacks because the sensitive data is distributed to the users with their private keys. This result shows that the access, write and update of electronic medical records are performed with the principles of security and privacy.

Analysis and Mitigation of Patterned Read Collisions in Flash SSDs

A modern flash solid-state drive (SSD) achieves superb throughput by accessing its flash memory dies in parallel. To obtain parallelism in processing writes, the flash translation layer (FTL) of an SSD is allowed to allocate physical pages from idle dies or dies with low loads. However, since the die that holds the page to be read is determined in advance, when multiple read requests head for one die, read collisions occur, and the read operations involved in the collisions must be serialized. These read collisions lead to a significant prolongation of read latency and, thus the degradation of throughput. As the density of flash dies increases, more pages are stored on a die, which is expected to result in more frequent read collisions. Unlike the write collisions that the DRAM buffer can absorb, read collisions directly affect user-experienced latency. Therefore, the severity of the problem is further increased. In this paper, we identify the impact of read collisions on performance with real-world traces. We also propose an approach that distinguishes patterned read collisions from accidental ones and mitigates the performance impact of patterned read collisions. By replicating frequently occurring pages involved in patterned read collisions, the proposed approach improves the average and tail read latency of an SSD. The evaluation through simulation with the 34 MSR Cambridge traces showed that 12 traces out of 34 earned read performance improvement larger than 10% and up to 37%. In addition, the tail read latency of 15 traces was reduced by at least 20% and by up to 53%. Only two traces showed negligible degradation in average and tail read latency by around 1%.

Building a Document-Oriented Warehouse Using NoSQL

The traditional data warehousing approaches should adapt to take into consideration novel needs and data structures. In this context, NoSQL technology is progressively gaining a place in the research and industry domains. This paper proposes an approach for building a NoSQL document-oriented warehouse (DocW). This approach has two methods, namely 1) document warehouse builder and 2) NoSQL-Converter. The first method generates the DocW schema as a galaxy model whereas the second one translates the generated galaxy into a document-oriented NoSQL model. This relies on two types of rules: structure and hierarchical rules. Furthermore, in order to help understanding the textual results of analytical queries on the NoSQL-DocW, the authors define two semantic operators S-Drill-Up and S-Drill-Down to aggregate/expand the terms of query. The implementation of our proposals uses MangoDB and Talend. The experiment uses the medical collection Clef-2007 and two metrics called write request latency and read request latency to evaluate respectively the loading time and the response time to queries.

Accurate and efficient follower log repair for Raft-replicated database systems

State machine replication has been widely used in modern cluster-based database systems. Most commonly deployed configurations adopt the Raft-like consensus protocol, which has a single strong leader which replicates the log to other followers. Since the followers can handle read requests and many real workloads are usually read-intensive, the recovery speed of a crashed follower may significantly impact on the throughput. Different from traditional database recovery, the recovering follower needs to repair its local log first. Original Raft protocol takes many network round trips to do log comparison between leader and the crashed follower. To reduce network round trips, an optimization method is to truncate the follower’s uncertain log entries behind the latest local commit point, and then to directly fetch all committed log entries from the leader in one round trip. However, if the commit point is not persisted, the recovering follower has to get the whole log from the leader. In this paper, we propose an accurate and efficient log repair (AELR) algorithm for follower recovery. AELR is more robust and resilient to follower failure, and it only needs one network round trip to fetch the least number of log entries for follower recovery. This approach is implemented in the open source database system OceanBase. We experimentally show that the system adopting AELR has a good performance in terms of recovery time.

Internal Task-Aware Command Scheduling to Improve Read Performance of Embedded Flash Storage Systems

Many NAND flash storage systems access flash memories by generating flash commands to process input/output (I/O) requests from a host system. Because the order in which flash commands are processed affects the I/O performance, command scheduling has been performed in previous studies to prioritize flash read commands for improving the read performance. However, in addition to the flash commands for accessing user data requested by the host, flash commands for internal tasks that improve the I/O performance and operation efficiency of the flash storage are issued. Particularly in embedded flash storage, the flash commands by the map cache management have a significant influence on the latency of I/O requests. The processing time of the I/O request depends on the execution time of the flash commands for mapping information and the flash commands for user data. In this paper, we propose command scheduling to improve read performance to address the occurrence of map flash commands. Priority is given to the flash read and program command from the read request, and among these commands, the flash command originating from the read request, which has a shorter processing time, is executed first. Consequently, the waiting time of the flash command is reduced, thereby improving the read latency. Experiments conducted with real workloads show that the proposed scheduling scheme reduces the average read latency by up to 51% compared with the existing scheduling scheme and demonstrates an effective performance improvement in a small map cache.

DedupHR: Exploiting Content Locality to Alleviate Read/Write Interference in Deduplication-based Flash Storage

The read/write interference problem of flash storage, where on-going write requests prevent read requests from accessing available data and significantly increase read latency, remains a critical concern with the rapid evolutions of flash chips from SLC through MLC to TLC and on to QLC, with PLC on the horizon, especially under workloads with a mixture of read and write requests. To significantly improve the read performance in face of read/write interference, which is often more critical than the write performance, we propose an enhanced Hot Read Data Replication scheme for deduplication-based flash storage, called DedupHR, to alleviate the read/write interference problem. DedupHR exploits the content locality in the deduplication-based flash storage and outsources the data blocks with high reference count to a surrogate space such as a dedicated spare flash chip or an over-provisioned space in an SSD. By servicing some conflicted read requests on the surrogate flash space, DedupHR can significantly alleviate, if not entirely eliminate, the contention between the read requests and the on-going write requests. The evaluation results show that DedupHR significantly improves the state-of-the-art schemes in terms of the system performance and cost efficiency. Consequently, the tail-latency of the deduplication-based flash storage is also reduced.