Lesson 11: File System
NTFS
"Journaling" file system
NTFS
"Rolls back" transactions if errors found
FAT
A file may be divided into many sections and scattered around the disk due to fragmentation. FAT keeps track of all pieces of a file like using a table of contents.
Disk File System
Additional considerations include the speed of accessing data following that initially requested and the anticipation that the following data may also be requested.
Design limitations
All file systems have some functional limit that defines the maximum storable data capacity within that system.
Migrating to a different file system
An alternative, when there is not sufficient space to retain the original file system until the new one is created, is to use a work area (such as a removable media).
Database file systems
Another concept for file management is the idea of a database-based file system. 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.
Restricting and permitting access
Another reason is to ensure data is modified in a controlled way so access may be restricted to a specific program.
Boot sector
Bootable partition that stores information about the layout of the vo lume and the file system structures. This loads the Ntldlr.
File System
By separating the data into individual pieces, and giving each piece a name, the information is easily separated and identified.
UFS
Compatible with FAT12 and FAT16; typically installed to enable UNIX to read floppy disks created in MS-DOS or Windows.
Master Boot Record
Contains executable code that th e system BIOS loads into memory.
Hard Disk
Contains one or more partitions.
NTFS Boot Sector
Contains the BIOS parameter block that store information about the layout of the volume and the file system structures, as well as the boot code that loads Windows Server 2003.
MFT
Contains the information necessary to retrieve from the NTFS partition, such as the attributes of a file.
File Utilities
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.
NFS
Developed by Sun Microsystem for UNIX systems to support network access and file sharing; supported in almost all UNIX/Linux Versions and many other operating systems.
NTFS
Developed last July, 1993 for Windows NT 3.1
Design Limitations
Disk storage has continued to increase at near exponential rates, 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.
Extended File System
EXT-4
Restricting and permitting access
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.
Ntoskrnl.exe
Extracts information about which system device drivers to load and the load order.
File Allocation Table
FAT
File Control Block
FCB
NTFS
File system developed by Microsoft
Space management
File systems allocate space in a granular manner, usually multiple physical units on the device.
Utilities
File systems include utilities to initialize, alter parameters of and remove an instance of the file system.
Directories
File systems typically have directories (also called folders) which allow the user to group files into separate collections.
"/ \=,^?
Filenames can contain any character except
Flash file system
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.
Multiple file systems within a single system
Frequently retail systems are configured with a single file system occupying the entire hard disk but you can actually use 2 or more file systems in a single disk using partitioning.
Hierarchical File System
HFS
High Performance File System
HPFS
Optical discs
ISO 9660 and UDF are two common formats that target Compact Discs, DVDs and Blu- ray discs.
Transactional file systems
If the installation is upgrading a key system utility, such as the command shell, the entire system may be left in an unusable state.
Transactional file system
If the software installation fails, the program may be unusable.
FAT
In DOS systems, it is stored after boot sector.
Long file paths and long file names
In hierarchical file systems, files are accessed by means of a path that is a branching list of directories containing the file.
In-place conversion
In some cases conversion can be done in-place, although migrating the file system is more conservative, as it involves creating a copy of the data and is recommended.
Other special file systems
In the Linux kernel, configfs and sysfs provide files that can be used to query the kernel for information and configure entities in the kernel. procfs maps processes and, on Linux, other OS structures into a filespace.
Master File Table Copy
Includes copies of the records essential for the recovery of the file system if there is a problem with the original copy.
FAT32 File System
It can be used on drives from 512MB to 2TB in size.
Reserved Sector
It includes an area called the BIOS Parameter Block (with some basic file system information, in particular its type, and pointers to the location of the other sections) and usually contains the operating system's boot loader code.
Converting the type of a file system
It may be advantageous or necessary to have files in a different file system than they currently exist.
FAT32
It supports larger disk (up to 2TB) and better storage efficiency.
NTFS
Keeps track of transaction performed.
Master File Table
MFT
Migrating to a different file system
Migration has the disadvantage of requiring additional space although it may be faster.
Network File System
NFS
New Technology File System
NTFS
HPFS
OS/2 and (optionally) Windows NT 3.x file system
FAT32
One of the most important features of FAT and it is that they offer compatibility with OS other than Windows 2000.
Maintaining Integrity
One significant responsibility of a file system is to ensure that, regardless of the actions by programs accessing the data, the structure remains consistent.
HFS
Originally designed for use on floppy and hard disks, it can also be found on read-only media such as CD-ROMs.
NTFS
Overcomes FAT system limitations
Converting the type of a file system
Reasons include the need for an increase in the space requirements beyond the limits of the current file system.
NTFS
Similar to database table with records
Tape Formatting
Similarly, completely erasing or formatting a tape can also take several hours. With many data tape technologies it is not necessary to format the tape before over-writing new data to the tape.
Utilities
Some include the ability to extend or truncate the space allocated to the file system.
Transactional file systems
Some programs need to update multiple files "all at once". For example, a software installation may write program binaries, libraries, and configuration files.
NTFS
Stores data about all files and directories
File System Data
Stores data that is not contained within the MFT.
Ntldlr.dll
Switches the CPU to protected m ode, starts the file system, and t hen reads the contents of the Boot.ini file.
Fastfat.sys
System file driver for FAT16 and FAT32.
File
Taking its name from the way paper-based information systems are named, each group of data is called a
FCB
The current size of a file was maintained in the file's
File Size
The current size of a file was maintained in the file's file control block (FCB) by the operating system.
Extended File System and EXT2, EXT3
The default Linux file system; the current version, EXT3, supports journalling
Converting the type of a file system
The depth of path may need to be increased beyond the restrictions of the file system.
Shared disk file systems
The file system arbitrates access to that subsystem, preventing write collisions.
Space Management
The file system is responsible for organizing files and directories, and keeping track of which areas of the media belong to which file and which are not being used.
Boot Sector
The first reserved sector (sector 0) is
Minimal file system / Audio-cassette storage
The late 1970s saw the development of the microcomputer. Disk and digital tape devices were too expensive for hobbyists. An inexpensive basic data storage system was devised that used common audio cassette tape.
User Data
The most important purpose of a file system is to manage it. This includes storing, retrieving and updating data.
User Mode
The processing mode in which applications run.
Kernel Mode
The processing mode that allows code to have direct access to all hardware and memory in the system.
File System
The structure and logic rules used to manage the groups of information and their names is called a _________
Restricting and permitting access
There are several mechanisms used by file systems to control access to data.
Converting the type of a file system
There may be performance or reliability considerations. Providing access to another operating system which does not support existing file system is another reason.
FAT Region
These are maps of the Data Region, indicating which clusters are used by files and directories.
Design Limitations
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.
File Utilities
They may be able to truncate data, truncate or extend space allocation, append to, move, and modify files in-place.
The Root Directory Region
This is a Directory Table that stores information about the files and directories located in the root directory.
Tape Formatting
This is due to the inherently destructive nature of overwriting data on sequential media.
Special file system
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.
The Data Region
This is where the actual file and directory data is stored and takes up most of the partition.
Directories
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.
FAT Region
This typically contains two copies (may vary) of the File Allocation Table for the sake of redundancy checking, although the extra copy is rarely used, even by disk repair utilities.
Uniform Disk Format
UDF
Unix File System
UFS
NTFS
Uses a Master File Table (MFT)
Restricting and permitting access
Usually the intent is to prevent reading or modifying files by a user or group of users.
Flat file system
When floppy disk media was first available this type of file system was adequate due to the relatively small amount of data space available.
Slack
With bigger disks is the large amount of wasted space or _______
File System
Without a it, information placed in a storage area would be one large body of data with no way to tell where one piece of information stops and the next begins.
Tape formatting
Writing data to a tape is often a significantly time-consuming process that may take several hours.
Amazon's S3
a remote storage service, which is intentionally simplistic to allow users the ability to customize how their data is stored.
Metadata
a set of data that describes and gives information about other data (e.g. the time that the file was last modified may be stored as the file's timestamp)
NFS
allows a system to share directories and files with others over a network.
Extended File Allocation Table
also called as "FAT64"
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.
Defragment Utility
arranges the file so that it will be stored in contiguous clusters.
EXFAT
can be used where the NTFS file system is not a feasible solution (due to data structure overhead), or where the file size limit of the standard FAT32 file system (that is, without FAT32+ extension) is unacceptable.
Flash file systems
considers the special abilities, performance and restrictions of flash memory devices.
File Utilities
create, list, copy, move and delete files, and alter metadata.
HPFS
developed by Microsoft & IBM
EXFAT
developed on November 2006 (Windows Embedded CE 6.0)
Fragmented
file is stored in noncontiguous clusters.
MSDOS
filename uses only 8 characters (8.3 or Short Filename)
Windows 2000
fully supports NTFS
FAT
has been used since the advent of PCs and was developed by Bill Gates and Marc McDonald during 1976-1977.
EXT-4
has metadata structure inspired by the traditional Unix File System (UFS) and was designed by Rémy Card to overcome certain limitations of the MINIX file system.
Network file system
include clients for the NFS, AFS, SMB protocols, and file-system-like clients for FTP and WebDAV.
EXFAT
is a Microsoft proprietary, patented file system designed especially for USB flash drives.
NFS
is a distributed file system protocol originally developed by Sun Microsystems in 1984, allowing a user on a client computer to access files over a computer network much like local storage is accessed.
Tape file systems
is a file system and tape format designed to store files on tape in a self-describing form.
Network file systems
is a file system that acts as a client for a remote file access protocol, providing access to files on a server.
FAT32
is an advanced version of FAT file system.
Mount Rainier
is an extension to UDF supported since 2.6 series of the Linux kernel and since Windows Vista that facilitates rewriting to DVDs.
HPFS
is best for drives in the 200-400 MB range.
HFS
is how drives, folders, and files are displayed on an operating system.
Shared disk file systems
is one in which a number of machines (usually servers) all have access to the same external disk subsystem (usually a SAN).
Ext-4
is the evolution of the most used Linux file system.
FAT
is used by the OS to store the physical location of all the files on a storage medium such as floppy disks or hard disks.
File System
is used to control how data is stored and retrieved.
File names
is used to identify a storage location in the file system.
HPFS
less fragmentation of data
Reserved Sectors
located at the very beginning.
Special file systems
presents non-file elements of an operating system as files so they can be acted on using file system APIs.
NTFS
provides file and folder security. Files and folders are safer than FAT.
FAT32
provides good file access in partition sizes less than 500 MB or greater than 2 GB. It provides better disk space utilization.
Device file systems
represents I/O devices and pseudo-devices as files, called device files.
HFS
s a proprietary file system developed by Apple Inc. for use in computer systems running Mac OS.
HPFS
share many features with NTFS
File size
specified as the number of 128-byte records occupied by a file on the disk.
HPFS
support for long file names (256 characters as opposed to FAT's 11 characters).
Windows 2000
supports long file name. The full path of file including filename can be up to 255 characters long.
Disk File System
takes advantages of the ability of disk storage media to randomly address data in a short amount of time.
Flat file system
there are no subdirectories.
HPFS
to improve limitations of FAT file system.
EXT-4
was implemented in April 1992 as the first file system created specifically for the Linux kernel.
