Technical Perspective

Byte-addressable persistent memory was considered in the data management community as long ago as 1986. Thatte saw the advantages for programmability in unifying the abstractions of byte-addressable RAM with persistence [2]. Thatte's context was object-oriented databases containing a variety data structures that would be awkward to transform into the block-oriented abstractions provided by typical secondary storage. Thatte's proposed physical instantiation of persistent memory was a disk-backed device, although it is unclear whether such a device was ever built. Thatte recognized the importance of recovery to the overall scheme.

A Comparative Analysis of Disk Scheduling Algorithms

In an operating system, disk scheduling is the process of managing the I/O request to the secondary storage devices such as hard disk. The speed of the processor and primary memory has increased in a rapid way than the secondary storage. Seek time is the important factor in an operating system to get the best access time. For the better performance, speedy servicing of I/O request for secondary memory is very important. The goal of the disk-scheduling algorithm is to minimize the response time and maximize throughput of the system. This work analyzed and compared various basic disk scheduling techniques like First Come First Serve (FCFS), Shortest Seek Time First (SSTF), SCAN, LOOK, Circular SCAN (C-SCAN) and Circular LOOK (C-LOOK) along with the corresponding seek time. From the comparative analysis, the result show that C-LOOK algorithm give the least head movement and seek time in different cases as compared to other algorithm. Therefore, it maximizes the throughput for the storage devices.

Perangkat keras komputer

Perangkat keras komputer adalah semua bagian fisik komputer, dan dibedakan dengan data yang berada di dalamnya atau yang beroperasi di dalamnya, dan dibedakan dengan perangkat lunak (software) yang menyediakan instruksi untuk perangkat keras dalam menyelesaikan tugasnya. Hardware dalam bahasa Indonesia disebut juga dengan nama perangkat keras yaitu salah satu komponen dari sebuah komputer yang sifat alatnya bisa dilihat dan diraba secara langsung atau yang berbentuk nyata, yang berfungsi untuk mendukung proses komputerisasi. Hardware dapat bekerja berdasarkan perintah yang telah ditentukan atau disebut juga dengan istilah instruction set. Berdasarkan fungsinya, perangkat keras komputer dibagi menjadi : Sistem Perangkat Keras Masukan (Input Device System), Sistem pemrosesan (Central processing system/ Central processing unit (CPU), Sistem perangkat keras keluaran (Output Device System), Sistem perangkat keras tambahan (Peripheral/Accessories Device System), Sistem perangkat keras cadangan (secondary storage/backing storage/external memory).

Hybrid Page Replacement Algorithm in real time Operating System

Programming codes are of variable length. When the size of codes becomes greater than that of primary memory, the concept of virtual memory comes into play. As the name suggests, virtual memory allows to outstretch the use of primary memory by using storage devices such as disks. The implementation of virtual memory can be done by using the paging approach. Allocation of memory frames to each and every program is done by the operating system while loading them into the memory. Each program is segregated into pages as per the size of frames. Equal size of pages and frames enhance the usability of memory. As, the process or program which is being executed is provided with a certain amount of memory frames; therefore, swap out technique is necessary for the execution of each and every page. This swap out technique is termed as Page Replacement. There are many algorithms proposed to decide which page needs to be replaced from the frames when new pages come. In this paper, we have proposed a new page replacement technique. This new technique is based on the approach of reading and counting of the pages from secondary storage. Whenever the page fault is detected, the needed page is fetched from the secondary storage. This process of accessing the disc is slow as compared to the process in which the required page is retrieved from the primary storage. In the proposed technique, the pages having least occurrence will be replaced by the new page and the pages having same count will be replaced on the basis of LRU page replacement algorithm. In this method, the paged are retrieved from the secondary storage hence, possibility of page hit will be increased and as a result, the execution time of the processes will be decreased as the possibility of page miss will be decreased.

Determining the Scope of Recovery from Physically Damaged Micro SD Card

Today’s use of secondary devices like cloud storage, Hard Disk, Pen Drive, SD, CDs, DVDs is constantly growing. Data might be deleted , loss or device is formatted accidentally or intentionally by various means. It’s a myth that “once secondary storage devices are damaged then there is no access to data too”. This article gives the detail investigation that from damaged devices too data can be recovered.

An Improved Page Replacement Algorithm Using Block Retrieval of Pages

The computer programmer write programming codes of any length without keeping in mind the available primary memory. This is possible if we use the concept of virtual memory. As the name suggests, virtual memory is a concept of executing a programming code of any size even having a primary memory of smaller size than the size of program to be executed. The virtual memory can be implemented using the concept of paging. The operating system allocates a number of memory frames to each program while loading into the memory. The programming code is equally divided into pages of same size as frame size. The size of pages and memory frames are retained equal for the better utilization of the memory. During the execution of program, every process is allocated limited number of memory frames; hence there is a need of page replacements. To overcome this limitation, a number of page replacement techniques had suggested by the researchers. In this paper, we have proposed an modified page replacement technique, which is based on the concept of block reading of pages from the secondary storage. The disc access is very slow as compared to the access from primary memory. Whenever there is a page fault, the required page is retrived from the secondary storage. The numerous page faults increase the execution time of process. In the proposed methodology, a number of pages, which is equal to the allotted memory frames, are read every time when there is a page fault instead of reading a single page at a time. If a block of pages has fetched from secondary storage, it will definitely increases the possibilities of page hit and as a result, it will improve the hit ratio for the processes.