Difference between revisions of "File Systems"
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= CD and DVD File Systems =
= CD and DVD File Systems =
Revision as of 12:20, 19 June 2011
Conventional File Systems
- Ext2, Ext3
- Ext2 was introduced with Linux. Ext3 is a journaled version of Ext2 which allows for speedy disk recovery after a crash.
- The Fast File System used by some BSD versions of UNIX and from which UFS was derived supporting faster disk access and symbolic links like ffs.
- IBM's Journaled File System introduced with their flavor of UNIX (AIX)
- The New Technology File System, introduced by Microsoft with Windows NT 4.0. Now used on Windows XP.
- A journaling filesystem for Linux.
- SGI’s high performance journaling filesystem that originated on their IRIX (flavor of UNIX) platform. XFS supports variable blocking sizes, is extent based, and makes extensive use of Btrees to facilitate both performance and scalability. Additionally, support is also provided for real-time environments.
Cryptographic File Systems
Cryptographic file systems, also known as encrypted file systems, encrypt information before it is stored on the media. Some of these file systems store encrypted files directly. Others are better thought of as device drivers, which are then used to store some of the file systems discussed above.
- File Vault
- A clever user interface to Apple's encrypted disk images. Uses the ".sparseimage" extension on disk files.
- Matt Blaze's Cryptographic File System for Unix.
- Key Management in an Encrypting File System, Matt Blaze, USENIX Summer 1994 Technical Conference, Boston, MA, June 1994.
- A Cryptographic File System for Unix, Matt Blaze, Proceedings of the First ACM Conference on Computer and Communications Security, Fairfax, VA, November 1993.
- EFS is the Encrypted File System built into versions of Microsoft Windows.
- NCryptfs: A Secure and Convenient Cryptographic File System, Charles P. Wright, Michael C. Martino, and Erez Zadok, Stony Brook University, USENIX 2003 Annual Technical Conference.
See also Full Disk Encryption, which are disk- or applicance-based cryptographic file systems.
CD and DVD File Systems
Optical media use different file systems than hard disks or flash media, primarily because of the write-once nature of most optical discs. Even rewritable discs use different file systems because of the way that rewritable media is managed. So while you will never find NTFS or FAT32 on an optical disc, you will find the systems listed below.
- HFS and HFS+
- These file systems are defined by Apple and only limited support is available for them outside of the Macintosh world. These are the identical implementations for hard disk file systems on MacOS operating systems.
- ISO 9660
- This is the most basic file system and the foundation for a number of extensions which have been made to it. It was originally defined in 1989 and was an outgrowth of the previous HSG (High Sierra Group) definition of a file system for CDs.
- This is a Microsoft defined extension to ISO 9660 to support Unicode and 64-character file names. It was introduced with Windows 95. It has gained some support for Linux and MacOS file systems but remains something that is used primarily in the Windows environment.
- Red Book
- The original definition of audio CDs was distributed with a red cover, hence the term "Red Book". This is not properly a file system as it does not define files, file names or any metadata. It is the definition by which music discs are created.
- Rock Ridge
- Rock Ridge is a set of extensions based on the System Use Sharing Protocol or SUSP definition. It is a method by which POSIX file attributes, including very long file names, can be applied to optical media. Today it is only really supported by Linux and other Unix-derived operating systems.
- UDF is the acronym for Universal Disk Format which was defined by the Optical Storage Technology Association as an implementable subset of ISO 13346. It is part of the definition for DVD Video and DVD Audio discs as well as being used by a number of drag-and-drop disc writing programs. It is supported for reading by Windows 98 and later versions and is supported beginning with OS 9 on the Macintosh. Both Windows Vista and Windows 7 can write discs using this as either a "mastered" format with a static, read-only file system or as a "live" file system which can be updated on both write-once and rewritable media.
Distributed File Systems
Distributed file systems, also known as network file systems, allow any number of remote clients to access one or more servers which store the files. The client nodes do not have direct access to the underlying block storage on the server(s), which are transparent to the clients and may include facilities for replication or fault tolerance.
- The GoogleFS clone, built from a cluster of data nodes.
- Originally from Sun, it is the standard in UNIX-based networks.