NTFS file system

NTFS is a flexible and powerful file system built, on an elegantly simple file system model. The most noteworthy feature of NTFS include .


1. Recoverability:-  high on the list of requirements for the new w2k file system was the ability to recover from file system crashes  and disk failure. In the event of such the failure, NTFS is able to reconstruct disk volumes and return them to a consistent state. It does this by using a transaction processing model for changes to the file system; each significant change is treat as an atomic action that is either entirely performed or not performed at all. Each transition that was in process at the time of a failure is subsequently backed out or brought to completion. In addition, NTFS uses redundant storage for critical file system data, So that failure of a disk sector does not cause of the loss of the data describing the structure and status of the file system.

2. Security:- NTFS uses the w2k object model to enforce security. An open file is implemented as a file object with a security descriptor that defines is security attributes.

3. Large Disks and Large File:- NTFS supports very large disks and very large files more efficiently than most other file systems, including FAT.

4.Multiple Data Streams:- The actual contents of a file are treated as a stream of bytes. In NTFS it is possible to define multiple data stream for a single file. An example of the utility of this computer of the utility of this feature is that the it allow w2k to be used by remote Macintosh systems to store and retrieve files. On Macintosh, each file has two components - the file data and a resource fork that contains information about the file. NTFS treats these two components as two data structure.


5.General Indexing Facility:- NTFS associates a collection of attributes with each file. The set of the description in the file management system  is organized as a relational databases, so that              files can be indexed by any attributes.

1.1 sector:- The smallest physical storage unit on the disk. The data size in  bytes is a power of 2 and is almost always 512 bytes.

1.2 Cluster:- One or more contiguous (next to each other on the same track) sectors. The cluster size in sectors in a power of 2.

1.3 Volume:-  A logical partition on a disk, consisting of one or more cluster and use a by file system to allocate space. At any time, a volume consists of a file system information, a collection of files, any additional unallocated space remaining on the volume that can be allocated files. A volume can be all or a portion of a single disk or it can extended across multiple disks. If hardware or software RAIDS 5 in employed, a volume consists of stripes spanning multiple disks. the maximum volume size for NTFS is 26
 bytes.

           The cluster is the fundamental unit of allocation in NTFS, which does not recognize sectors. For example, suppose each sector is 512 bytes and the system is configured with two sectors per cluster (one cluster=1k bytes). If a user creates a file of 1600 bytes, two clusters are allocated to the file. Later, if the user updates the file to 320 bytes, another two cluster are allocated.

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