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Filesystem
In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one large body of data with no way to tell where one piece of data stopped and the next began, or where any piece of data was located when it was time to retrieve it. By separating the data into pieces and giving each piece a name, the data are easily isolated and identified. Taking its name from the way a paper-based data management system is named, each group of data is called a " file". The structure and logic rules used to manage the groups of data and their names is called a "file system." There are many kinds of file systems, each with unique structure and logic, properties of speed, flexibility, security, size and more. Some file systems have been designed to be used for specific applications. For example, the ISO 9660 file system is desig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Procfs
The proc filesystem (procfs) is a special filesystem in Unix-like operating systems that presents information about processes and other system information in a hierarchical file-like structure, providing a more convenient and standardized method for dynamically accessing process data held in the kernel than traditional tracing methods or direct access to kernel memory. Typically, it is mapped to a mount point named ''/proc'' at boot time. The proc file system acts as an interface to internal data structures about running processes in the kernel. In Linux, it can also be used to obtain information about the kernel and to change certain kernel parameters at runtime ( sysctl). Many Unix-like operating systems support the proc filesystem, including Solaris, IRIX, Tru64 UNIX, BSD, Linux, IBM AIX, QNX, and Plan 9 from Bell Labs. OpenBSD dropped support in version 5.7, released in May 2015. It is absent from HP-UX and macOS. The Linux kernel extends it to non–process-rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tmpfs
tmpfs (short for Temporary File System) is a temporary file storage paradigm implemented in many Unix-like operating systems. It is intended to appear as a mounted file system, but data is stored in volatile memory instead of a persistent storage device. A similar construction is a RAM disk, which appears as a virtual disk drive and hosts a disk file system. Semantics Everything stored in tmpfs is temporary in the sense that no files will be directly created on non-volatile storage such as a hard drive (although swap space is used as backing store in case of low memory situations). On reboot, everything in tmpfs will be lost. The memory used by tmpfs grows and shrinks to accommodate the files it contains. Many Unix distributions enable and use tmpfs by default for the branch of the file system or for shared memory. This can be observed with as in this example: Filesystem Size Used Avail Use% Mounted on tmpfs 256M 688K 256M 1% /tmp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sysfs
sysfs is a pseudo file system provided by the Linux kernel that exports information about various kernel subsystems, hardware devices, and associated device drivers from the kernel's device model to user space through virtual files. In addition to providing information about various devices and kernel subsystems, exported virtual files are also used for their configuration. sysfs provides functionality similar to the sysctl mechanism found in BSD operating systems, with the difference that sysfs is implemented as a virtual file system instead of being a purpose-built kernel mechanism, and that, in Linux, ''sysctl'' configuration parameters are made available at ''/proc/sys/'' as part of procfs, not sysfs which is mounted at ''/sys/''. History During the 2.5 development cycle, the Linux driver model was introduced to fix the following shortcomings of version 2.4: * No unified method of representing driver-device relationships existed. * There was no generic hotplug mecha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO 9660
ISO 9660 (also known as ECMA-119) is a file system for optical disc media. Being sold by the International Organization for Standardization (ISO) the file system is considered an international technical standard. Since the specification is available for anybody to purchase, implementations have been written for many operating systems. ISO 9660 traces its roots to the ''High Sierra Format'', which arranged file information in a dense, sequential layout to minimize nonsequential access by using a hierarchical (eight levels of directories deep) tree file system arrangement, similar to UNIX and FAT. To facilitate cross platform compatibility, it defined a minimal set of common file attributes (directory or ordinary file and time of recording) and name attributes (name, extension, and version), and used a separate system use area where future optional extensions for each file may be specified. High Sierra was adopted in December 1986 (with changes) as an international standard ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network File System (protocol)
Network File System (NFS) is a distributed file system protocol originally developed by Sun Microsystems (Sun) in 1984, allowing a user on a client computer to access files over a computer network much like local storage is accessed. NFS, like many other protocols, builds on the Open Network Computing Remote Procedure Call (ONC RPC) system. NFS is an open IETF standard defined in a Request for Comments (RFC), allowing anyone to implement the protocol. Versions and variations Sun used version 1 only for in-house experimental purposes. When the development team added substantial changes to NFS version 1 and released it outside of Sun, they decided to release the new version as v2, so that version interoperation and RPC version fallback could be tested. NFSv2 Version 2 of the protocol (defined in RFC 1094, March 1989) originally operated only over User Datagram Protocol (UDP). Its designers meant to keep the server side stateless, with locking (for exampl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disk Quota
A disk quota is a limit set by a system administrator that restricts certain aspects of file system usage on modern operating systems. The function of using disk quotas is to allocate limited disk space in a reasonable way. Types of quotas There are two basic types of disk quotas. The first, known as a ''usage quota'' or ''block quota'', limits the amount of disk space that can be used. The second, known as a ''file quota'' or ''inode quota'', limits the number of files and directories that can be created. In addition, administrators usually define a warning level, or ''soft quota'', at which users are informed they are nearing their limit, that is less than the effective limit, or ''hard quota''. There may also be a small ''grace interval'', which allows users to temporarily violate their quotas by certain amounts if necessary. Quotas Disk quotas are typically implemented on a per-user or per-group basis. That is, a system administrator defines a usage or file quota specific to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
9P (protocol)
9P (or the Plan 9 Filesystem Protocol or Styx) is a network protocol developed for the Plan 9 from Bell Labs distributed operating system as the means of connecting the components of a Plan 9 system. Files are key objects in Plan 9. They represent windows, network connections, processes, and almost anything else available in the operating system. 9P was revised for the 4th edition of Plan 9 under the name 9P2000, containing various improvements. Some of the improvements made are the removal of certain filename restrictions, the addition of a 'last modifier' metadata field for directories, and authentication files. The latest version of the Inferno operating system also uses 9P2000. The Inferno file protocol was originally called Styx, but technically it has always been a variant of 9P. A server implementation of 9P for Unix, called u9fs, is included in the Plan 9 distribution. A 9P OS X client kernel extension is provided by Mac9P. A kernel client driver implementing 9P w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Device Driver
In computing, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabling operating systems and other computer programs to access hardware functions without needing to know precise details about the hardware being used. A driver communicates with the device through the computer bus or communications subsystem to which the hardware connects. When a calling program invokes a routine in the driver, the driver issues commands to the device (drives it). Once the device sends data back to the driver, the driver may invoke routines in the original calling program. Drivers are hardware dependent and operating-system-specific. They usually provide the interrupt handling required for any necessary asynchronous time-dependent hardware interface. Purpose The main purpose of device drivers is to provide abstraction by acting as a translator b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Storage Device
Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a computer is what manipulates data by performing computations. In practice, almost all computers use a storage hierarchy, which puts fast but expensive and small storage options close to the CPU and slower but less expensive and larger options further away. Generally, the fast volatile technologies (which lose data when off power) are referred to as "memory", while slower persistent technologies are referred to as "storage". Even the first computer designs, Charles Babbage's Analytical Engine and Percy Ludgate's Analytical Machine, clearly distinguished between processing and memory (Babbage stored numbers as rotations of gears, while Ludgate stored numbers as displacements of rods in shuttles). This distinction was extended in the Von Neumann a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File System Fragmentation
In computing, file system fragmentation, sometimes called file system aging, is the tendency of a file system to lay out the contents of files non-continuously to allow in-place modification of their contents. It is a special case of data fragmentation. File system fragmentation negatively impacts seek time in spinning storage media, which is known to hinder throughput. Fragmentation can be remedied by re-organizing files and free space back into contiguous areas, a process called defragmentation. Solid-state drives do not physically seek, so their non-sequential data access is hundreds of times faster than moving drives', making fragmentation a non-issue. It is recommended to not defragment solid-state storage, because this can prematurely wear drives via unnecessary write–erase operations. Causes When a file system is first initialized on a partition, it contains only a few small internal structures and is otherwise one contiguous block of empty space. This means that th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apple DOS
Apple DOS is the family of disk operating systems for the Apple II series of microcomputers from late 1978 through early 1983. It was superseded by ProDOS in 1983. Apple DOS has three major releases: DOS 3.1, DOS 3.2, and DOS 3.3; each one of these three releases was followed by a second, minor "bug-fix" release, but only in the case of Apple DOS 3.2 did that minor release receive its own version number, Apple DOS 3.2.1. The best-known and most-used version is Apple DOS 3.3 in the 1980 and 1983 releases. Prior to the release of Apple DOS 3.1, Apple users had to rely on audio cassette tapes for data storage and retrieval. Version history When Apple Computer introduced the Apple II in April 1977, the new computer had no disk drive or disk operating system (DOS). Although Apple co-founder Steve Wozniak designed the Disk II controller late that year, and believed that he could have written a DOS, his co-founder Steve Jobs decided to outsource the task. The company considered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Server Message Block
Server Message Block (SMB) is a communication protocol originally developed in 1983 by Barry A. Feigenbaum at IBM and intended to provide shared access to files and printers across nodes on a network of systems running IBM's OS/2. It also provides an authenticated inter-process communication (IPC) mechanism. In 1987, Microsoft and 3Com implemented SMB in LAN Manager for OS/2, at which time SMB used the NetBIOS service atop the NetBIOS Frames protocol as its underlying transport. Later, Microsoft implemented SMB in Windows NT 3.1 and has been updating it ever since, adapting it to work with newer underlying transports: TCP/IP and NetBT. SMB implementation consists of two vaguely named Windows services: "Server" (ID: LanmanServer) and "Workstation" (ID: LanmanWorkstation). It uses NTLM or Kerberos protocols for user authentication. In 1996, Microsoft published a version of SMB 1.0 with minor modifications under the Common Internet File System (CIFS ) moniker. CIFS was comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
