Ms dos file system mac

There is none.. Mchl Mchl Have you count the LFN extension? So it is indeed dependent on how the OS handles the regular FAT32 file-system as opposed to being a variant. Simon Liu Simon Liu 5 5 silver badges 20 20 bronze badges. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. Featured on Meta. Congratulations to our 29 oldest beta sites - They're now no longer beta!

Unicorn Meta Zoo 7: Interview with Nicolas. Experiment: closing and reopening happens at 3 votes for the next 30 days…. Should we burninate the [heisenbug] tag? This may be implemented by associating the file name with an index in a table of contents or an inode in a Unix-like file system. Directory structures may be flat i.

The first file system to support arbitrary hierarchies of directories was used in the Multics operating system. Other bookkeeping information is typically associated with each file within a file system. The length of the data contained in a file may be stored as the number of blocks allocated for the file or as a byte count. The time that the file was last modified may be stored as the file's timestamp.

File systems might store the file creation time, the time it was last accessed, the time the file's metadata was changed, or the time the file was last backed up. Other information can include the file's device type e. A file system stores all the metadata associated with the file—including the file name, the length of the contents of a file, and the location of the file in the folder hierarchy—separate from the contents of the file.

Most file systems store the names of all the files in one directory in one place—the directory table for that directory—which is often stored like any other file. Many file systems put only some of the metadata for a file in the directory table, and the rest of the metadata for that file in a completely separate structure, such as the inode. Most file systems also store metadata not associated with any one particular file. Such metadata includes information about unused regions— free space bitmap , block availability map —and information about bad sectors.

Often such information about an allocation group is stored inside the allocation group itself. Some file systems provide for user defined attributes such as the author of the document, the character encoding of a document or the size of an image. Some file systems allow for different data collections to be associated with one file name. These separate collections may be referred to as streams or forks. Some file systems maintain multiple past revisions of a file under a single file name; the filename by itself retrieves the most recent version, while prior saved version can be accessed using a special naming convention such as "filename;4" or "filename -4 " to access the version four saves ago.

See comparison of file systems Metadata for details on which file systems support which kinds of metadata. In some cases, a file system may not make use of a storage device but can be used to organize and represent access to any data, whether it is stored or dynamically generated e.


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  • File system?

File systems include utilities to initialize, alter parameters of and remove an instance of the file system. Some include the ability to extend or truncate the space allocated to the file system. Directory utilities may be used to create, rename and delete directory entries , which are also known as dentries singular: dentry , [10] and to alter metadata associated with a directory.

Directory utilities may also include capabilities to create additional links to a directory hard links in Unix , to rename parent links "..

Mac OS Extended

File utilities create, list, copy, move and delete files, and alter metadata. They may be able to truncate data, truncate or extend space allocation, append to, move, and modify files in-place. Depending on the underlying structure of the file system, they may provide a mechanism to prepend to or truncate from, the beginning of a file, insert entries into the middle of a file or delete entries from a file. Utilities to free space for deleted files, if the file system provides an undelete function, also belong to this category.

Some file systems defer operations such as reorganization of free space, secure erasing of free space, and rebuilding of hierarchical structures by providing utilities to perform these functions at times of minimal activity. An example is the file system defragmentation utilities. Some of the most important features of file system utilities involve supervisory activities which may involve bypassing ownership or direct access to the underlying device. These include high-performance backup and recovery, data replication and reorganization of various data structures and allocation tables within the file system.

There are several mechanisms used by file systems to control access to data. Usually the intent is to prevent reading or modifying files by a user or group of users. Another reason is to ensure data is modified in a controlled way so access may be restricted to a specific program.

Examples include passwords stored in the metadata of the file or elsewhere and file permissions in the form of permission bits, access control lists , or capabilities. The need for file system utilities to be able to access the data at the media level to reorganize the structures and provide efficient backup usually means that these are only effective for polite users but are not effective against intruders. Methods for encrypting file data are sometimes included in the file system.

This is very effective since there is no need for file system utilities to know the encryption seed to effectively manage the data. The risks of relying on encryption include the fact that an attacker can copy the data and use brute force to decrypt the data. Losing the seed means losing the data. One significant responsibility of a file system is to ensure that, regardless of the actions by programs accessing the data, the structure remains consistent.

This includes actions taken if a program modifying data terminates abnormally or neglects to inform the file system that it has completed its activities. This may include updating the metadata, the directory entry and handling any data that was buffered but not yet updated on the physical storage media. Other failures which the file system must deal with include media failures or loss of connection to remote systems. In the event of an operating system failure or "soft" power failure, special routines in the file system must be invoked similar to when an individual program fails.

The file system must also be able to correct damaged structures. These may occur as a result of an operating system failure for which the OS was unable to notify the file system, power failure or reset. The file system must also record events to allow analysis of systemic issues as well as problems with specific files or directories. The most important purpose of a file system is to manage user data. This includes storing, retrieving and updating data. Some file systems accept data for storage as a stream of bytes which are collected and stored in a manner efficient for the media.

When a program retrieves the data, it specifies the size of a memory buffer and the file system transfers data from the media to the buffer. A runtime library routine may sometimes allow the user program to define a record based on a library call specifying a length.

When the user program reads the data, the library retrieves data via the file system and returns a record. Some file systems allow the specification of a fixed record length which is used for all writes and reads.

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This facilitates locating the n th record as well as updating records. An identification for each record, also known as a key, makes for a more sophisticated file system. The user program can read, write and update records without regard to their location. This requires complicated management of blocks of media usually separating key blocks and data blocks.

Very efficient algorithms can be developed with pyramid structure for locating records. Utilities, language specific run-time libraries and user programs use file system APIs to make requests of the file system.


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These include data transfer, positioning, updating metadata, managing directories, managing access specifications, and removal. Frequently, retail systems are configured with a single file system occupying the entire storage device.

Mac 101: Format choices for USB flash drives

Another approach is to partition the disk so that several file systems with different attributes can be used. One file system, for use as browser cache, might be configured with a small allocation size. This has the additional advantage of keeping the frantic activity of creating and deleting files typical of browser activity in a narrow area of the disk and not interfering with allocations of other files. A similar partition might be created for email.

Another partition, and file system might be created for the storage of audio or video files with a relatively large allocation. One of the file systems may normally be set read-only and only periodically be set writable. A third approach, which is mostly used in cloud systems, is to use " disk images " to house additional file systems, with the same attributes or not, within another host file system as a file. The ext4 file system resides in a disk image, which is treated as a file or multiple files, depending on the hypervisor and settings in the NTFS host file system. Having multiple file systems on a single system has the additional benefit that in the event of a corruption of a single partition, the remaining file systems will frequently still be intact.

This includes virus destruction of the system partition or even a system that will not boot. File system utilities which require dedicated access can be effectively completed piecemeal. In addition, defragmentation may be more effective. Several system maintenance utilities, such as virus scans and backups, can also be processed in segments. For example, it is not necessary to backup the file system containing videos along with all the other files if none have been added since the last backup.

As for the image files, one can easily "spin off" differential images which contain only "new" data written to the master original image. Differential images can be used for both safety concerns as a "disposable" system - can be quickly restored if destroyed or contaminated by a virus, as the old image can be removed and a new image can be created in matter of seconds, even without automated procedures and quick virtual machine deployment since the differential images can be quickly spawned using a script in batches.

All file systems have some functional limit that defines the maximum storable data capacity within that system [ citation needed ]. These functional limits are a best-guess effort by the designer based on how large the storage systems are right now and how large storage systems are likely to become in the future. Disk storage has continued to increase at near exponential rates see Moore's law , so after a few years, file systems have kept reaching design limitations that require computer users to repeatedly move to a newer system with ever-greater capacity.

File system complexity typically varies proportionally with the available storage capacity. Likewise, modern file systems would not be a reasonable choice for these early systems, since the complexity of modern file system structures would quickly consume or even exceed the very limited capacity of the early storage systems. A disk file system takes advantages of the ability of disk storage media to randomly address data in a short amount of time.

Additional considerations include the speed of accessing data following that initially requested and the anticipation that the following data may also be requested. This permits multiple users or processes access to various data on the disk without regard to the sequential location of the data. Some disk file systems are journaling file systems or versioning file systems.

Mount Rainier is an extension to UDF supported since 2. A flash file system considers the special abilities, performance and restrictions of flash memory devices. Frequently a disk file system can use a flash memory device as the underlying storage media but it is much better to use a file system specifically designed for a flash device. A tape file system is a file system and tape format designed to store files on tape in a self-describing form [ clarification needed ]. Magnetic tapes are sequential storage media with significantly longer random data access times than disks, posing challenges to the creation and efficient management of a general-purpose file system.

In a disk file system there is typically a master file directory, and a map of used and free data regions. Random access to data regions is measured in milliseconds so this system works well for disks. Tape requires linear motion to wind and unwind potentially very long reels of media. Consequently, a master file directory and usage map can be extremely slow and inefficient with tape. Writing typically involves reading the block usage map to find free blocks for writing, updating the usage map and directory to add the data, and then advancing the tape to write the data in the correct spot.

Each additional file write requires updating the map and directory and writing the data, which may take several seconds to occur for each file. Tape file systems instead typically allow for the file directory to be spread across the tape intermixed with the data, referred to as streaming , so that time-consuming and repeated tape motions are not required to write new data.

However, a side effect of this design is that reading the file directory of a tape usually requires scanning the entire tape to read all the scattered directory entries. Most data archiving software that works with tape storage will store a local copy of the tape catalog on a disk file system, so that adding files to a tape can be done quickly without having to rescan the tape media.

The local tape catalog copy is usually discarded if not used for a specified period of time, at which point the tape must be re-scanned if it is to be used in the future. The Linear Tape File System uses a separate partition on the tape to record the index meta-data, thereby avoiding the problems associated with scattering directory entries across the entire tape. Writing data to a tape, erasing, or formatting a tape is often a significantly time-consuming process and can take several hours on large tapes. This is due to the inherently destructive nature of overwriting data on sequential media.

Because of the time it can take to format a tape, typically tapes are pre-formatted so that the tape user does not need to spend time preparing each new tape for use. All that is usually necessary is to write an identifying media label to the tape before use, and even this can be automatically written by software when a new tape is used for the first time. Another concept for file management is the idea of a database-based file system.

Single User Mode

Instead of, or in addition to, hierarchical structured management, files are identified by their characteristics, like type of file, topic, author, or similar rich metadata. Around to Frank G. Soltis and his team at IBM Rochester have successfully designed and applied technologies like the database file system where others like Microsoft later failed to accomplish.

Some other projects that aren't "pure" database file systems but that use some aspects of a database file system:. Some programs need to either make multiple file system changes, or, if one or more of the changes fail for any reason, make none of the changes. If some of the writing fails and the software is left partially installed or updated, the software may be broken or unusable. An incomplete update of a key system utility, such as the command shell , may leave the entire system in an unusable state.

Difference between FAT32, exFAT, and NTFS File System

Transaction processing introduces the atomicity guarantee, ensuring that operations inside of a transaction are either all committed or the transaction can be aborted and the system discards all of its partial results. This means that if there is a crash or power failure, after recovery, the stored state will be consistent. Either the software will be completely installed or the failed installation will be completely rolled back, but an unusable partial install will not be left on the system. Transactions also provide the isolation guarantee [ clarification needed ] , meaning that operations within a transaction are hidden from other threads on the system until the transaction commits, and that interfering operations on the system will be properly serialized with the transaction.

Ensuring consistency across multiple file system operations is difficult, if not impossible, without file system transactions. File locking can be used as a concurrency control mechanism for individual files, but it typically does not protect the directory structure or file metadata. File locking also cannot automatically roll back a failed operation, such as a software upgrade; this requires atomicity. Journaling file systems is one technique used to introduce transaction-level consistency to file system structures.

Journal transactions are not exposed to programs as part of the OS API; they are only used internally to ensure consistency at the granularity of a single system call. Data backup systems typically do not provide support for direct backup of data stored in a transactional manner, which makes the recovery of reliable and consistent data sets difficult. Most backup software simply notes what files have changed since a certain time, regardless of the transactional state shared across multiple files in the overall dataset.

As a workaround, some database systems simply produce an archived state file containing all data up to that point, and the backup software only backs that up and does not interact directly with the active transactional databases at all. Recovery requires separate recreation of the database from the state file after the file has been restored by the backup software. A network file system is a file system that acts as a client for a remote file access protocol, providing access to files on a server. Programs using local interfaces can transparently create, manage and access hierarchical directories and files in remote network-connected computers.

A shared disk file system is one in which a number of machines usually servers all have access to the same external disk subsystem usually a SAN. The file system arbitrates access to that subsystem, preventing write collisions. A special file system presents non-file elements of an operating system as files so they can be acted on using file system APIs. This is most commonly done in Unix-like operating systems, but devices are given file names in some non-Unix-like operating systems as well.

Examples in Unix-like systems include devfs and, in Linux 2. In non-Unix-like systems, such as TOPS and other operating systems influenced by it, where the full filename or pathname of a file can include a device prefix, devices other than those containing file systems are referred to by a device prefix specifying the device, without anything following it. In the s disk and digital tape devices were too expensive for some early microcomputer users. An inexpensive basic data storage system was devised that used common audio cassette tape. The system wrote a sound to provide time synchronization, then modulated sounds that encoded a prefix, the data, a checksum and a suffix.

When the system needed to read data, the user was instructed to press "PLAY" on the cassette recorder. The system would listen to the sounds on the tape waiting until a burst of sound could be recognized as the synchronization. The system would then interpret subsequent sounds as data. When the data read was complete, the system would notify the user to press "STOP" on the cassette recorder.

It was primitive, but it worked a lot of the time. Data was stored sequentially, usually in an unnamed format, although some systems such as the Commodore PET series of computers did allow the files to be named. Multiple sets of data could be written and located by fast-forwarding the tape and observing at the tape counter to find the approximate start of the next data region on the tape.

The user might have to listen to the sounds to find the right spot to begin playing the next data region. Some implementations even included audible sounds interspersed with the data. In a flat file system, there are no subdirectories ; directory entries for all files are stored in a single directory. When floppy disk media was first available this type of file system was adequate due to the relatively small amount of data space available. These user areas were no more than special attributes associated with the files; that is, it was not necessary to define specific quota for each of these areas and files could be added to groups for as long as there was still free storage space on the disk.

It was unusual in that the file management program Macintosh Finder created the illusion of a partially hierarchical filing system on top of EMFS. This structure required every file to have a unique name, even if it appeared to be in a separate folder. While simple, flat file systems become awkward as the number of files grows and makes it difficult to organize data into related groups of files. A recent addition to the flat file system family is Amazon 's S3 , a remote storage service, which is intentionally simplistic to allow users the ability to customize how their data is stored.

The only constructs are buckets imagine a disk drive of unlimited size and objects similar, but not identical to the standard concept of a file. Many operating systems include support for more than one file system. Sometimes the OS and the file system are so tightly interwoven that it is difficult to separate out file system functions.


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  4. There needs to be an interface provided by the operating system software between the user and the file system. This interface can be textual such as provided by a command line interface , such as the Unix shell , or OpenVMS DCL or graphical such as provided by a graphical user interface , such as file browsers. If graphical, the metaphor of the folder , containing documents, other files, and nested folders is often used see also: directory and folder. Unix-like operating systems create a virtual file system, which makes all the files on all the devices appear to exist in a single hierarchy.

    This means, in those systems, there is one root directory , and every file existing on the system is located under it somewhere. Unix-like systems can use a RAM disk or network shared resource as its root directory. Unix-like systems assign a device name to each device, but this is not how the files on that device are accessed. Instead, to gain access to files on another device, the operating system must first be informed where in the directory tree those files should appear.

    This process is called mounting a file system. It may be empty, or it may contain subdirectories for mounting individual devices. Generally, only the administrator i. Unix-like operating systems often include software and tools that assist in the mounting process and provide it new functionality. Some of these strategies have been coined "auto-mounting" as a reflection of their purpose. SquashFS is a common compressed read-only file system.

    Solaris in earlier releases defaulted to non-journaled or non-logging UFS for bootable and supplementary file systems.

    How to Format External Hard Drive for Mac & Windows (MS-Dos or ExFat?)

    Solaris defaulted to, supported, and extended UFS. Support for other file systems and significant enhancements were added over time, including Veritas Software Corp. Multiple operating systems including Solaris may use Veritas Volume Manager. Modern Solaris based operating systems eclipse the need for volume management through leveraging virtual storage pools in ZFS. Later versions of HFS Plus added journaling to prevent corruption of the file system structure and introduced a number of optimizations to the allocation algorithms in an attempt to defragment files automatically without requiring an external defragmenter.

    Filenames can be up to characters.