UNIX Time-Sharing System: The MERT Operating System

Dr Paulino Ruiz-de-Clavijo from Universidad de Sevilla in Spain talks about the research behind his Letter ‘NanoFS: hardware-oriented file system’ on page 1216. Dr Paulino Ruiz-de-Clavijo During my higher education as a computer engineer I have always been interested in low-level programming and digital electronic circuits. In 1999 I started my PhD research at the University of Seville and the National Microelectronics Centre - CSIC, which I completed at the ID2 research group of the University of Seville. That period allowed me to start working with reprogrammable devices; FPGAs in particular. This technology fascinated me because it opened up the possibility to reuse my knowledge and experience in software programming to develop hardware using hardware description languages (HDLs), and I found the hardware-software codesign a great field to explore. The research in our group involves the wide field of hardware-software codesign and reconfigurable hardware. Our work is mainly focused on the design of digital embedded systems and SoC (system on chip) on FPGAs and the design of application-specific peripherals for SoC. Relating to SoCs, we have worked with open platforms like the LEON and OpenRISC soft-core microprocessors. In our group we have also developed hardware for industrial projects like a SNTP synchronisation platform based on FPGA and a frequency synchroniser for OFDM systems. We have developed a new file system called ‘nano file system’ (NanoFS) which is specially tailored to be implemented in hardware. It has been designed from scratch keeping in mind the hardware implementation limitations. The main objective is to be able to do file system operations just with digital circuits while keeping a minimum hardware footprint. The approach keeps the high level file system features and it can be used in both low level embedded systems and high-level operating systems. An all-hardware file system reader core is presented in our Letter which has been successfully implemented and tested in a low-range FPGA device. It can be included in custom designs to read data from files stored in external storage media. Most file systems are designed with two overall objectives: to be optimal for the storage medium and/or to be optimal when implemented in software. Our proposal is a hardware-friendly file system suitable for embedded systems. The file system can be used without an operating system or before the operating system is booted. File systems like FAT or EXT2 are widely used in electronic devices and SoC. The layouts of these traditional file systems are intended to be managed with software algorithms. When these algorithms are translated to HDL, a large amount of resources are necessary. There have been a few initiatives to develop file systems for embedded systems to solve these problems that simplifies data structures and improves some software routines. These file systems are written in C and supply an API for some microcontrolers but are not designed to achieve a hardware implementation. Some custom designs in hardware require dynamic configuration, such as the network configuration, calibration parameters, etc. In previous work we developed a SNTP synchronisation server designed as a full hardware solution to improve the precision. To try different configurations of these servers, we had to reprogram the FPGA device. We thought that a data file in a file system that could be accessed directly from the device hardware would be a faster and more flexible method to achieve that. We created NanoFS to solve the problems we found when we tried to access other file systems from hardware. Currently, from a software perspective, a dedicated file manager application is used to access the file system. We are working to improve a Linux native driver for NanoFS so we can access the files right from the operating system. At this moment the driver works in read-only mode. We are also migrating the file manager to the MS Windows platform. From the hardware perspective, we are developing some new hardware cores with write support. We plan to test the write support module with current solid state disks to measure the performance. Further applications we have planned to use the new file system are: data acquisition systems; boot loaders for embedded systems; and FPGA dynamic reconfiguration.

The z/OS operating system offers a strong and well- organized dataset management System that enables the efficient storage, retrieval, and processing of data through high-volume andmission - critical workloads by large corporations. This paper delves into the intricacy of the z/OS operating system's file management, moreso its unique but most sophisticated dataset structures and UNIX System Services (USS) file system. This paper explores various dataset organizations, record structures, and accessmethods native to z/OS. This paper also talks abouthowthetraditional z/OS datasetsintegrate with the hierarchical file system of USS,with a focus oncoexistence and interoperation between the two environments. This paper aims to comprehensively understand the z/OS file systems and datasets by comparing similar technologies outside of zOS and using coding examples.

The file system is one of the most critical components of the operating system. Almost all applications running in the operating system require file systems to be available for their proper operation. Though file-system availability is critical in many cases, very little work has been done on tolerating file system crashes. In this paper, we propose Membrane, a set of changes to the operating system to support restartable file systems. Membrane allows an operating system to tolerate a broad class of file system failures and does so while remaining transparent to running applications; upon failure, the file system restarts, its state is restored, and pending application requests are serviced as if no failure had occurred. Our initial evaluation ofMembrane with ext2 shows thatMembrane induces little performance overhead and can tolerate a wide range of file system crashes. More critically, Membrane does so with few changes to ext2, thus improving robustness to crashes without mandating intrusive changes to existing filesystem code.

With the coming of the Internet of things(IoT) era and the development of semiconductor equipment, multicore processors have begun to be widely used in IoT devices to meet their requirements for powerful processing capabilities. Unlike desktop or server operating systems such as Linux, current embedded operating systems often do not support multi-core processors well. Tasks on different cores often require information exchange, known as inter-core communication, which significantly impacts the processing performance of multi-core operation systems. In this paper, we proposed an inter-core communication method based on signal transmission and shared memory, which is flexible and various types of data can be transferred efficiently. We have implemented and experimented with it on our own microkernel operating system named Mginkgo. The experimental results show that the average time to trigger an inter-core interrupt is about 0.093 microseconds. The average inter-core interrupt processing time is about 3.986 microseconds. And the communication time of the system for multi-core Inter-Process Communication(IPC) is about 18us, which is the same as that of single-core IPC. The inter-core communication method proposed in this paper achieves very low latency with almost no performance consumption and maintains the high performance of the whole system.

Byte addressable non-volatile (NV) memory, such as STT-RAM, MRAM, and PCM, is the next generation memory that can be used as both main memory and secondary storage. While it can persistently store data without power supply, its access speed is comparable to DRAM. While there have been the active researches on its use for either main memory or secondary storage, these researches were conducted independently. This paper presents the integration methods of the main memory and file system management for NV memory, so that it can be used as both main memory and storage. The presented methods use a file system as their basis for the NV memory management; thus, the internal data structures of a file system can have impacts upon the performance of the integration methods. We implemented the proposed methods in the Linux kernel, and performed the evaluation on a system emulator. The evaluation results show that 1) the proposed methods can perform comparably to the existing DRAM memory allocator and significantly better than the page swapping, 2) their performance is affected by the internal data structures of a file system, and 3) the data structures appropriate for traditional hard disk drives do not always work effectively for byte addressable NV memory.

The File Allocation Table (FAT) file system is widely used file system in tablet personal computers, mobile phones, digital cameras and other embedded devices for data storage and multi-media applications such as video imaging, audio/video playback and recording. The FAT file system is not power fail-safe. This means that, the uncontrolled power loss or abrupt removal of storage device from computer/embedded system causes the file system corruption. The TFAT (Transaction safe FAT) file system is an extension of FAT file system to provide power fail-safe feature to the FAT file system. This paper explores the design methodologies of cluster allocation algorithms of TFAT file system by conducting various combinations of file system operations in Windows CE (Compact Embedded) 6.0 Operating System (OS). This paper also records the performance bench-marking of TFAT file system in comparison with FAT File system.

Advances in network and processor technology have greatly changed the communication and computational power of local-area workstation clusters. However, operating systems still treat workstation clusters as a collection of loosely-connected processors, where each workstation acts as an autonomous and independent agent. This operating system structure makes it difficult to exploit the characteristics of current clusters, such as low-latency communication, huge primary memories, and high-speed processors, in order to improve the performance of cluster applications. This paper describes the design and implementation of global memory management in a workstation cluster. Our objective is to use a single, unified, but distributed memory management algorithm at the lowest level of the operating system. By managing memory globally at this level, all system- and higher-level software, including VM, file systems, transaction systems, and user applications, can benefit from available cluster memory. We have implemented our algorithm in the OSF/1 operating system running on an ATM-connected cluster of DEC Alpha workstations. Our measurements show that on a suite of memory-intensive programs, our system improves performance by a factor of 1.5 to 3.5. We also show that our algorithm has a performance advantage over others that have been proposed in the past.

This paper describes a simple distributed mechanism for caching files among a networked collection of workstations. We have implemented it as part of Sprite, a new operating system being implemented at the University of California at Berkeley. A preliminary version of Sprite is currently running on Sun-2 and Sun-3 workstations, which have about 1-2 MIPS processing power and 4-16 Mbytes of main memory. The system is targeted for workstations like these and newer models likely to become available in the near future; we expect the future machines to have at least five to ten times the processing power and main memory of our current machines, as well as small degrees of multiprocessing. We hope that Sprite will be suitable for networks of up to a few hundred of these workstations. Because of economic and environmental factors, most workstations will not have local disks; instead, large fast disks will be concentrated on a few server machines.

The world keeps contributing to the increase in data everyday drastically. Scientific applications, weather forecasting, researches, hospitals, military services are few such major contributors. As the amount of data increases, the need to provide efficient, easy to use solutions has become one of the main issues for these type of computations. The best solution to this issue is the use of Distributed File Systems(DFS). Some existing Distributed File Systems are too complex to deploy and maintain, although they are extremely scalable and cheap since they can be entirely built out of commodity Operating System(OS) and hardware. GlusterFS solves this problem. Gluster File System(GFS) is open source and is capable of scaling to several petabytes(upto 72 brontobytes) and handling thousands of clients. It is based on a stackable user space design and can deliver exceptional performance for diverse workloads. GlusterFS is an easy to use clustered file system that meets enterprise-level requirements. It is written in user space which uses FUSE(Filesystem in user space) to hook itself with the VFS layer. It takes a layered approach to the file system, where features are added/removed as per the requirement. Enforcer is a major component in Gluster which finds its extensive use in production. Enforcer is concerned more about limits. It helps to restrict the usage(both in terms of size and count) at directory or volume level in the file system. In this paper, we discuss the internal working of the translators and key architectural components of GlusterFS. Along with that, one can gain a deep insight about the enforcement techniques, few challenges, undergoing researches and projects of GlusterFS

Consistent improvements in processor and memory technology have led to disks having greater processing power and cache memory in a compact size. This increased processing power and memory allows disks to execute more than just the basic disk operations, sometimes, even run user defined codes. Offloading part of the application processing to the disks can help reducing the latency of data manipulation as well as the amount of data transferred across the network. Such disks are called active disks. In this paper, a file system for the active-disk-based data server (ADFS) is proposed. All data files stored on active disks are provided with operations, forming objects. For some applications such as database, application-specific operations can be run by disk processors so that only the results are returned to clients, rather than whole data file is read by the clients. Therefore, ADFS is able to reduce the application-processing overhead of the system. In ADFS, part of file system functionality of the file manager can be delegated to active disks. Our implementation is based on CORBA specification. A set of file system interfaces is implemented for each module of each file system component. Part of the file system functionality, such as lookup, is embedded in the modules for active disks. We tested the performance of ADFS with 64 files in three-layer directory system. The performance results are obtained in a limited manner and presented in this paper. Our ADFS is basically stateful, but the delegation of file system functionality to disks allows our file system to be more scalable and helps to overcome some of the limitations of current prevailing file systems, like NFS, by greatly reducing the work of the central file manager. In addition, it is conceivable that the central file manager could be eliminated altogether.

Organizing documents in the file system is one of the most tedious and thorny tasks for most computer users. Taxonomies based on hand made directory hierarchies still remain the only possible alternative for most small and medium enterprises, public administrations and individual users. However, both the limitations of the hierarchical organization of file systems and the difficulty of maintaining the coherence within the taxonomy have raised the need for more scalable and effective approaches.Desktop searching applications provide proprietary interfaces that enable content-based searching at the cost of having no control on the indexing and ranking of results. Semantic file systems, instead, leave users the freedom to manage the taxonomy according to their specific needs, but lose the standard file system features.In this paper we describe GFS (graph-based file system) a new hybrid file system that extends the standard hierarchical organization of files with semantic features. GFS allows the user to nest semantic spaces inside the directory hierarchy leaving unaltered system folders. Semantic spaces allow customized file tagging and leverage on browsing to guide file searching.Since GFS does not change the low-level interface to interact with file systems, users can continue to use their favorite file managers to interact with it. Moreover, no changes are required to integrate the semantic features in proprietary software.

As one of most outstanding embedded real-time systems, QNX operating system is widely used on many key areas. Increasingly mature virtual machine technique is brought into QNX graphical interface program development to establish a "Host machine-Target machine" mode. On one computer, the developing platform for QNX graphical interface program is set up. Test results indicate that the developing platform obviously increases the efficiency of QNX interface program development and is suggested to other system programs development.

Vendors cannot provide all the operating-system services that users demand. So, there has been a persistent desire to make operating systems more flexible and customizable. Naturally, object-oriented technology has come to bear on this area. However the ease of use of many such solutions has been disappointing. Ease of use is a key feature of Frigate, an object-oriented file system. It differs from most file system designs in that it's for ordinary users, not sophisticated operating system gurus. Frigate's modular, extensible framework allows new extensions to be "plugged in" on the fly. It is fully implemented and supports a set of example file system extensions.

Microsoft’s file system, NTFS, is the most utilised file system by Windows OS versions XP, Vista, 7, and 10. These systems have a little-known file attribute feature known as alternate data streams (ADS) which allows each file in the NTFS file system to have multiple data streams. ADS cannot be removed from the NTFS operating systems. However, the presence of ADS is not inevitably an issue in the OS or file system. Valid instances can be found on systems if scanned and might be valid. Windows OS does not have any in-built tools or applications to determine and remove the presence of existing ADS. This research presents ADSA or alternate data stream attack framework to exploit the alternate data streams and perform cyberattacks on Microsoft operating systems. This research discusses the process of creating and searching alternate data streams with a standard file and an executable binary. The authors executed ADS-hidden executable binary in the ADS. The authors present methods to detect and perform a clean-up by deleting the alternate data stream.

Installation and Configuration of Tru64 UNIX