Logging Scheme Research Articles

A New Method for Measuring Water Holdup of Oil-Water Two-Phase Flow in Horizontal Wells

The production profile logging technology of Oil-water two-phase flow is an important support technology for efficient development of horizontal oil wells. Moreover, the water holdup of Oil-water two-phase flow is one of the important dynamic measurement parameters for production profile logging technology. Flow patterns in horizontal oil wells are more complex than those in vertical oil wells, making water holdup measurements more difficult. In China, horizontal oil wells are characterized by low liquid production, high water cut and layered development; hence, the concentrating flow logging scheme is adopted to reduce the effects of flow patterns on measurement. In this paper, we proposed a new method of measuring water holdup of Oil-water two-phase flow for the production profile logging in horizontal oil wells. Firstly, the structure of water holdup sensors and the measuring principle of water holdup were introduced. Secondly, the dynamic test research was carried out on the horizontal well simulation facility by using the test prototype of the water holdup measurement method of Oil-water two-phase flow. Additionally, the response characteristics of water holdup sensors at five inclined angles were emphatically discussed. Finally, the measurement error of water holdup was calculated and evaluated in detail. Experimental results show that the absolute values of measurement error of water holdup are less than 5% while the total flow rate ranged from 10 m3/d to 200 m3/d, and the water cut ranged from 30% to 90%, respectively.

Building Reliable Massive Capacity SSDs through a Flash Aware RAID-Like Protection

The demand for mass storage devices has become an inevitable consequence of the explosive increase in data volume. The three-dimensional (3D) vertical NAND (V-NAND) and quad-level cell (QLC) technologies rapidly accelerate the capacity increase of flash memory based storage system, such as SSDs (Solid State Drives). Massive capacity SSDs adopt dozens or hundreds of flash memory chips in order to implement large capacity storage. However, employing such a large number of flash chips increases the error rate in SSDs. A RAID-like technique inside an SSD has been used in a variety of commercial products, along with various studies, in order to protect user data. With the advent of new types of massive storage devices, studies on the design of RAID-like protection techniques for such huge capacity SSDs are important and essential. In this paper, we propose a massive SSD-Aware Parity Logging (mSAPL) scheme that protects against n-failures at the same time in a stripe, where n is protection strength that is specified by the user. The proposed technique allows for us to choose the strength of protection for user data. We implemented mSAPL on a trace-based simulator and evaluated it with real-world I/O workload traces. In addition, we quantitatively analyze the error rates of a flash based SSD for different RAID-like configurations with analytic models. We show that mSAPL outperforms the state-of-the-art RAID-like technique in the performance and reliability.

Taurus

Existing single-stream logging schemes are unsuitable for in-memory database management systems (DBMSs) as the single log is often a performance bottleneck. To overcome this problem, we present Taurus, an efficient parallel logging scheme that uses multiple log streams, and is compatible with both data and command logging. Taurus tracks and encodes transaction dependencies using a vector of log sequence numbers (LSNs). These vectors ensure that the dependencies are fully captured in logging and correctly enforced in recovery. Our experimental evaluation with an in-memory DBMS shows that Taurus's parallel logging achieves up to 9.9X and 2.9X speedups over single-streamed data logging and command logging, respectively. It also enables the DBMS to recover up to 22.9X and 75.6X faster than these baselines for data and command logging, respectively. We also compare Taurus with two state-of-the-art parallel logging schemes and show that the DBMS achieves up to 2.8X better performance on NVMe drives and 9.2X on HDDs.

Incremental Checkpointing for Fault-Tolerant Stream Processing Systems: A Data Structure Approach

As the demand of high-speed stream processing grows, in-memory databases are widely used to analyze streaming data. It is challenging for in-memory systems to meet the requirements of high throughput and data persistence at the same time since data are not stored in disks. ARIES logging and command logging are two popular logging methods. In current applications, both ARIES logging and command logging are necessary. However, no checkpointing mechanism includes both the functions of ARIES logging method and command logging method. Besides, adopting ARIES logging method in an in-memory database creates high overhead. Command logging records redundant commands and has high storage cost. To address the above issues, we utilize order-irrelevant characteristics of data structure and incremental checkpointing concepts to devise a data structure based incremental checkpointing (DSIC) mechanism. DSIC mechanism is a very low overhead checkpointing approach while retaining the features of ARIES logging and command logging. DSIC mechanism reduces more than 70 percent logging time of the existing logging scheme and saves 40 percent storage costs of the existing logging scheme.

DistLog: A distributed logging scheme for IoT forensics

Digital forensics are vital in the Internet of Things (IoT) domain. This is due to the enormous growth of cyber attacks and their widespread use against IoT devices. While IoT forensics do not prevent IoT attacks, they help in reducing their occurrence by tracing their source, tracking their root causes and designing the corresponding countermeasures. However, modern IoT attacks use anti-forensics techniques to destroy or modify any important digital evidence including log files. Anti-forensics techniques complicate the task for forensic investigators in tracking the attack source. Thus, countermeasures are required to defend against anti-forensics techniques. In this paper, we aim at securing the IoT log files to prevent anti-forensics techniques that target the logs’ availability and integrity such as wiping and injecting attacks. In the proposed solution, and at regular intervals of time, the logs generated by IoT devices are aggregated, compressed and encrypted. Afterwards, the encrypted logs are fragmented, authenticated and distributed over n storage nodes, based on the proposed Modified Information Dispersal Algorithm (MIDA) that can ensure log files availability with a degree of (n−t). For data dispersal, two cases are considered: the case where the fog nodes are interconnected and the case where they are not. For the former case, the n obtained fragments are transmitted to n neighboring IoT devices (aggregation nodes). However, for the latter one, the output is transmitted to the corresponding fog and then, dispersed over the n neighboring fog nodes. A set of security and performance tests were performed showing the effectiveness and robustness of the proposed solution in thwarting well-known security attacks.

Минимизация транспортной на¬грузки на трелевочные волоки при выборе схемы освоения лесосеки

Минимизация транспортной на¬грузки на трелевочные волоки при выборе схемы освоения лесосеки

ECLASS: Edge-Cloud-Log Assuring-Secrecy Scheme for Digital Forensics

User activity logs are important pieces of evidence in digital forensic investigations. In cloud forensics, it is difficult to collect user activity logs due to the fact of virtualization technologies and the multitenancy environment, which can infringe upon user privacy when collecting logs. Furthermore, the computing paradigm is shifting from conventional cloud computing toward edge computing, employing the advances of 5G network technology. This change in the computing paradigm has also brought about new challenges for digital forensics. Edge nodes that are close to users are exposed to security threats, and the collection of logs with limited computing resources is difficult. Therefore, this study proposes a logging scheme that considers log segmentation and distributed storage to collect logs from distributed edge nodes and to protect log confidentiality by taking into account edge-cloud characteristics. This scheme protects the integrity of log data collected by a multi-index chain network. To demonstrate the performance of the proposed scheme, edge nodes with three different capacity types were used, and the proposed log-segmentation method performed 29.4% to 64.2% faster than the Cloud-Log Assuring-Secrecy Scheme (CLASS) using 2048 bit Rivest-Shamir-Adleman (RSA) in three types of edge nodes for log-confidentiality protection. The log segmentation of edge CLASS (eCLASS) reduced the log size to approximately 58% less than CLASS log encryption, and edge-node CPU usage was also reduced from 14% to 28%.

Secure logging scheme for forensic analysis in cloud

SummaryCloud computing has emerged as a prominent technology that provides reliable on‐demand cloud services to users. Among the various kind of attacks, Distributed Denial of Service (DDoS) attack is one of the major application layer attacks that target the resources and services running in the cloud. Due to the distributed nature of attacks or crimes in the cloud, the evidence are collected from various components such as the router, switches, hard disk, log traces, and virtual machines. An attacker may collude with the cloud provider or investigators to tamper the log files or by inserting false information or by deleting the malicious activity logs altogether by leaving no trace. Hence, security is the major concern in cloud wherein investigation of crimes and attacks are very difficult. Collecting logs from the cloud providers is very hard since many users share the same network resources and the investigators rely on the providers to access the information. Therefore, in order to preserve the confidentiality, integrity, and authentication of logs, secure logging scheme is proposed to preserve the logs for forensic investigation. This paper highlights the secure logging scheme by extracting the features from logs of all virtual machine instances by double encryption scheme and also deals the integrity of the logs using hashing and verifies the signatures using Bloom filter–based R tree (BR tree). Furthermore, the verification is performed using Shamir Secret Sharing (SSS) scheme, and it is responsible for sharing the secret (private) keys to all the three parties, ie, user, investigator, and cloud providers. It is inferred from the experimental results that the proposed scheme requires minimal log processing time, minimal verification time for inserting logs, stores logs in time, and space efficient manner and scalable than existing methods.

A Logging Scheme for Reducing Update Workloads in Flash Storage

By caching dirty pages in memory space of a buffering pool, a database system can reduce expensive physical I/O’s required in page updates. If any data page cached has constant updates on itself, it seems to stay long in the buffering pool without flushing-out. Although the existence of such aged dirty pages can reduce the amount of physical updates in storage, it is apt to prolong time taken for recovery procedure after system failure. To prevent such a delayed recovery time, database systems usually take an approach of flushing aged dirty pages in a background mode. Even though the approach may be beneficial in the case of HDD storage, this may not be the case for flash storage because of its high update costs. To solve this problem, we proposed a new logging scheme and a recovery algorithm running with it. Since aged dirty pages in our method are written into a dedicated log file, rather than into data area in storage, we can evade frequent updating of them. To reduce the amount of log data written for that purpose, our logging scheme uses a small size of snapshot log. Since the write of a snapshot log record can put the redo start point forwards, we can guarantee the fast recovery procedure, while reducing the number of page updates. Due to reduced update workloads, our method can improve the overall throughput of flash storage.

Efficient distributed memory management with RDMA and caching

Recent advancements in high-performance networking interconnect significantly narrow the performance gap between intra-node and inter-node communications, and open up opportunities for distributed memory platforms to enforce cache coherency among distributed nodes. To this end, we propose GAM, an efficient distributed in-memory platform that provides a directory-based cache coherence protocol over remote direct memory access (RDMA). GAM manages the free memory distributed among multiple nodes to provide a unified memory model, and supports a set of user-friendly APIs for memory operations. To remove writes from critical execution paths, GAM allows a write to be reordered with the following reads and writes, and hence enforces partial store order (PSO) memory consistency. A light-weight logging scheme is designed to provide fault tolerance in GAM. We further build a transaction engine and a distributed hash table (DHT) atop GAM to show the ease-of-use and applicability of the provided APIs. Finally, we conduct an extensive micro benchmark to evaluate the read/write/lock performance of GAM under various workloads, and a macro benchmark against the transaction engine and DHT. The results show the superior performance of GAM over existing distributed memory platforms.

SQL statement logging for making SQLite truly lite

The lightweight codebase of SQLite was helpful in making it become the de-facto standard database in most mobile devices, but, at the same time, forced it to take less-complicated transactional schemes, such as physical page logging, journaling, and force commit, which in turn cause excessive write amplification. Thus, the write IO cost in SQLite is not lightweight at all. In this paper, to make SQLite truly lite in terms of IO efficiency for the transactional support, we propose SQLite/SSL , a per-transaction SQL statement logging scheme: when a transaction commits, SQLite/SSL ensures its durability by storing only SQL statements of small size, thus writing less and performing faster at no compromise of transactional solidity. Our main contribution is to show that, based on the observation that mobile transactions tend to be short and exhibit strong update locality , logical logging can, though long discarded, become an elegant and perfect fit for SQLite-based mobile applications. Further, we leverage the WAL journal mode in vanilla SQLite as a transaction-consistent checkpoint mechanism which is indispensable in any logical logging scheme. In addition, we show for the first time that byte-addressable NVM (non-volatile memory) in host-side can realize the full potential of logical logging because it allows to store fine-grained logs quickly. We have prototyped SQLite/SSL by augmenting vanilla SQLite with a transaction-consistent checkpoint mechanism and a redo-only recovery logic, and have evaluated its performance using a set of synthetic and real workloads. When a real NVM board is used as its log device, SQLite/SSL can outperform vanilla SQLite's WAL mode by up to 300x and also outperform the state-of-the-arts SQLite/PPL scheme by several folds in terms of IO time.

Failure-Atomic Slotted Paging for Persistent Memory

The slotted-page structure is a database page format commonly used for managing variable-length records. In this work, we develop a novel "failure-atomic slotted page structure" for persistent memory that leverages byte addressability and durability of persistent memory to minimize redundant write operations used to maintain consistency in traditional database systems. Failure-atomic slotted paging consists of two key elements: (i) in-place commit per page using hardware transactional memory and (ii) slot header logging that logs the commit mark of each page. The proposed scheme is implemented in SQLite and compared against NVWAL, the current state-of-the-art scheme. Our performance study shows that our failure-atomic slotted paging shows optimal performance for database transactions that insert a single record. For transactions that touch more than one database page, our proposed slot-header logging scheme minimizes the logging overhead by avoiding duplicating pages and logging only the metadata of the dirty pages. Overall, we find that our failure-atomic slotted-page management scheme reduces database logging overhead to 1/6 and improves query response time by up to 33% compared to NVWAL.

Failure-Atomic Slotted Paging for Persistent Memory

The slotted-page structure is a database page format commonly used for managing variable-length records. In this work, we develop a novel "failure-atomic slotted page structure" for persistent memory that leverages byte addressability and durability of persistent memory to minimize redundant write operations used to maintain consistency in traditional database systems. Failure-atomic slotted paging consists of two key elements: (i) in-place commit per page using hardware transactional memory and (ii) slot header logging that logs the commit mark of each page. The proposed scheme is implemented in SQLite and compared against NVWAL, the current state-of-the-art scheme. Our performance study shows that our failure-atomic slotted paging shows optimal performance for database transactions that insert a single record. For transactions that touch more than one database page, our proposed slot-header logging scheme minimizes the logging overhead by avoiding duplicating pages and logging only the metadata of the dirty pages. Overall, we find that our failure-atomic slotted-page management scheme reduces database logging overhead to 1/6 and improves query response time by up to 33% compared to NVWAL.

Design and formal verification of a cloud compliant secure logging mechanism

Security concerns are still retarding cloud adoption. While the research community work on clearing these concerns, an optimistic fair cloud compliant logging scheme may ease the cloud to spread. This study proposes a secure logging mechanism. The mechanism employs an online bulletin board as a public write-only storage for the log records. The bulletin board also acts as a trusted third party during conflict resolution. The secure logging protocol describes how the log records are distributed to the stakeholders. The protocol's security is verified with model checking tools and no security threats could be found.

Responses of regeneration and species coexistence to single-tree selective logging for a temperate mixed forest in eastern Eurasia

The altered proportion of Korean pine to broadleaved tree species following selective logging strongly affected post-harvest regeneration and species coexistence pattern in a temperate mixed broadleaved/Korean pine forest in eastern Eurasian. Species interaction should be considered when implementing selective logging schemes. It has been documented widely that selective logging can exert varied influences on post-harvested forest structure and dynamics via different logging intensity and rotation. However, few studies have been extended to evaluate the effects of the tree species selected for removal, which is also a critical component in prescribing a selective harvest plan. To clarify the effects and underlying mechanisms of logged tree species selection on species coexistence and regeneration pattern in post-harvested mixed broadleaved/Korean pine (Pinus koraiensis Siebold & Zucc.) forest in Changbai Mountains, China. Four types of plots were established based on different selection of logged tree species. Stand structure, spatial distribution pattern and spatial association of major tree species were analyzed using spatial point pattern (SPP) analysis. The effect of soil nitrogen concentration on forest regeneration was also examined through a Pearson correlation analysis. Sapling density of both Korean pine and commercially valuable broadleaved tree species was significantly greater on plots where Korean pines were logged than on plots where only commercial broadleaved trees were removed. Soil N and density of saplings were not correlated. SPP analysis showed strong negative spatial association between mature Korean pine and saplings of most tree species in most sampling plots. The proportion of Korean pine to broadleaved tree species selected for removal can lead to different stand structure and spatial distribution patterns of tree locations. Due to species–specific competition effects, such variations in spatial association of tree locations can exert varied effects on regeneration in this pine-dominated Eurasian temperate forest. To promote post-harvest tree regeneration and species coexistence, forest managers in this region should consider controlling the density of competition-superior trees such as large-size Korean pines when implementing a selective logging scheme.

THE REORGANIZATION OF TIMBER INDUSTY OF THE SOVIET KARELIA AFTER THE WINTER WAR

The paper focuses on the changes in timber industry management in the Soviet Karelia in 1940-1941. In the 1930’s the government of the republic lost control over logging. However, after the Winter War the former Finnish territories the Karelian Isthmus and the Northern Ladoga region with several large pulp and paper mills and woodworking enterprises were annexed to the newly formed Karelo-Finnish Union Republic. It resulted in the changes of the logging scheme and flows of raw wood. The governing body of the Karelo-Finnish SSR prevented the formation of a departmental “enclave” with union People’s Commissars for timber and paper industries entirely controlling logging and wood processing on the new territories. The leaders of the Karelo-Finnish SSR managed to persuade the central authorities in their ability to supply raw wood for the new factories and regained control over logging on the whole territory of the republic.

An Auxiliary Log Area for In-Page Logging Scheme

An Auxiliary Log Area for In-Page Logging Scheme

스토리지 클래스 메모리를 위한 롤백-복구 방식의 데이터 일관성 유지 기법

Storage Class Memory(SCM) has been considered as a next-generation storage device because it has positive advantages to be used both as a memory and storage. However, there are significant problems of data consistency in recently proposed file systems for SCM such as insufficient data consistency or excessive data consistency-control overhead. This paper proposes a novel data consistency-control scheme, which changes the write mode for log data depending on the modified data ratio in a block, using a rollback-recovery scheme instead of the Write Ahead Logging (WAL) scheme. The proposed scheme reduces the log data size and the synchronization cost for data consistency. In order to evaluate the proposed scheme, we implemented our scheme on a Linux 3.10.2-based system and measured its performance. The experimental results show that our scheme enhances the write throughput by 9 times on average when compared to the legacy data consistency control scheme.

Towards Securing Databases on Mobile Devices: A Log-based Approach

Mobile devices like smart phones empower their users to download, install, and execute a spectrum of attractive applications from both service providers and third parties. Consequently, users are increasingly relying on such devices not only for storing personal data but also for enabling purchases, managing finances, tracking diets, transacting business, and supporting social interactions. But the software systems on these devices are less robust than their laptop and desktop counterparts. These two factors can only entice attackers to manipulate the users’ personal data via malicious code or malware that exploits the weaknesses of these mobile systems. Furthermore, mobile devices are often stolen or misplaced and the stored data, which users value more than the hardware, compromised. Since an application typically uses its own database on the mobile device to store pertinent user data, our aim is to enhance the security of those databases. We propose a consolidated logging scheme that reflects all transactions performed on all those databases. Only a part of this log needs to be stored on the mobile device, thus addressing the conflict between space limitation in these devices and the space requirement of logging. Our scheme is tamper-resistant; by modeling adversaries with various degrees of strength, we formally test our claim of tamper resistance against them. We explain how our scheme addresses the problems created by malware and theft and helps restore lost data.

스마트기기 사용 증거 확보를 위한 로깅 연구

일반적으로 로깅은 안전한 컴퓨터 시스템을 위한 중요한 요소인데, 이러한 로그를 분석함으로써 컴퓨터 내부에서 발생하는 다양한 문제를 식별하거나 침입을 발견할 수 있다. 따라서, 로그 내의 정보를 잘 활용한다면, 각종 사이버 침해에 대한 스마트 기기의 증거자료를 확보는 물론 사이버 수사에서 포렌식 관점의 효력을 가지도록 할 수도 있다. 본 논문은 스마트기기를 위한 새로운 로깅 방안을 제안한다. 제안 방안은 스마트기기용 로깅의 요구사항을 모두 만족하므로, 스마트기기의 디지털 증거를 수집하기 위한 안전한 로깅 방안을 개발하는데 도움이 될 것이다. Logging is an important part of any secure computer system. By analyzing logs in computer systems, you can identify early various problems and detect intrusions by attackers. Also logs can use to collect digital evidences in smart devices and to be forensics value for cybercrime investigations. In this paper, we propose a new logging scheme for smart devices and improve it to apply various environments. The proposed scheme satisfies the requirements of logging for smart devices. Thus it will help to develop a better logging in smart devices for digital evidences.