QUESTION

Another method of organising disk files in NTFS used in some later versions of windows. Research and reports on how the NTFS system keeps track of file locations. What are its strengths and weakness? How does it handle large number of files and long file names?

SOLUTION

Introduction

NTFS is a file system based on HPFS file system.  The file system was created by IBM and Microsoft in collaboration and the file system was initially prepared for Windows NT platform but after that all recent version of windows i.e. windows XP, Vista and windows 7 have this file system. This is complex file system than previous file systems offered by windows and also offers increased security and performance features.

Tracking file locations

A hard disk is divided into divisions/ partitions at the time of disk formatting.  The operating system is responsible for tracking all files which are stored in each partition by that operating system. The files are stored in clusters which are disk spaces of uniform size.  In case of NTFS, the clusters range from a size from minimum of 512 bytes to maximum of 64 kilobytes. The clusters are not divisible further. The cluster size in NTFS system is based on the efficient usage of the space available on disk and the number of accesses that are required for accessing a single file. In case of NTFS, the default cluster size of the disk varies directly to size of the hard disk as it is assumed that a user prefers high performance on the cost of inefficiency of space.

It is cited as “The selection of the cluster size is a trade-off between efficient use of disk space and the number of disk accesses required to access a file.” (TechTarget)

When a file is being created using NTFS, a master file table is created which stores record about the created file.  This file is special file which is used for tracking information about every file created using NTFS.  The records saved in Master file table are used for locating a file.  NTFS always tries to store the entire file in a contiguous storage space i.e. using simultaneous clusters for storing a file.  Each file stores its data content along with some attributes which specifies details of file i.e. metadata.

NTFS architecture

Master file table

Whenever a disk in formatted with NTFS, a master table file is created along with metadata files on partition. The master table file is a name given to relational database. This relational database contains columns and rows where each column refers to metadata of the file and rows contain records related to each file stored on disk. This master file table stores information about itself and for this reason, first sixteen records of this file are reserved by NTFS.  Metadata files which are saved with a name which starts with a dollar sign are specified master file table’s table metadata files.  The remaining records are responsible for storing records of folders and file on disk.

It is cited as “Because the MFT stores information about itself, NTFS reserves the first 16 records of the MFT for metadata files (approximately 16 KB), which are used to describe the MFT” (TechNet, 2012)

The master file table stored following metadata on the master file table

• Standard information
• Attribute list
• File name
• Data
• Index root
• Index location
• Object id
• Volume information
• Bitmap
• Reliability: NTFS ensures reliability by addressing three main areas i.e. hot fixing, fatal signal sector failure removal, and recoverability.  Recoverability is ensured by transactions tracking. Fatal single sector failure is avoided by employing special objects on disk. These objects are tracked and protected for preventing any sector failure. Support to hot fixing is also given by NTFS. The recoverability feature of NTFS is provided in such a way that there is not any requirement to run disk repair utility.
• NTFS is much more flexible than that of previous file systems
• NTFS is best to use on high volumes as upon increase in volume of disk, there is no degradation of performance is faced in this file system
• NTFS supports a feature called as Alternate Data Stream i.e. ADS. This feature supports resource forks in hierarchical file system.
• NTFS also provides disk integrity. For this feature, NTFS performs disk recovery operations every time a volume is mounted or dismounted.
• NTFS also provide a technique which is called as cluster remapping which is responsible for minimizing bad sector effects of NTFS volumes.
• High space overhead: a main problem with NTFS file system is that a large amount of space overhead is required by this system for functioning. Space overhead refers to amount of data storage space which is occupied by file system and is not available for storing data. This space overhead is nearly 4 MB in a 100 MB partition.
• File naming limitations
• There are number of file naming limitations in NTFS. The system is not able to distinguish lowercase letters from uppercase letters. Also there are number of characters which cannot be included in file name. Some of these characters are /\ * <> etc
• Incompatibility with operating system
• NTFS is not compatible with windows 98, 95, ME and DOS.
• Floppy disk formatting is not supported
• NTFS do not support floppy disk formatting. Reason behind this is requirement of space overhead.

Advantages of NTFS

Disadvantages of NTFS

Handling Larger file names

A Unicode character set is used by NTFS system for naming files. This character set excludes some special characters such as * /\ etc. for handling long file names, these long files names are converted to small file names by removes all the spaces used in file name along with deleting all periods and keeping only one period.  There can be a condition that some of long names of files can result in same short names, at this points following methodology is used

Using first two characters for creating short file name

The next for letters are generated by mathematical manipulation of long file name

~1 is appended to the file name

An example of such long file name conversion is given below

This is Test 5.txt will be converted to THISIS`5.TXT

Whenever user deleted a file stored on disk, the smaller name created for the file will also be deleted.  The method of creating short file name is carried for improving performance.

References

Technet,2008. NTFS,viewed on 21^st may http://searchwindowsserver.techtarget.com/definition/NTFS

Technet,2003.How NTFS works, viewed on 21^st may 2012,http://technet.microsoft.com/en-us/library/cc781134(v=ws.10).aspx

Hamel,2010.the disadvantages of NTFS file system,viewed on 21^st may 2012, http://www.scribd.com/doc/51574213/The-Disadvantages-of-an-NTFS-File-System

LF00

But you can order it from our service and receive complete high-quality custom paper.  Our service offers Technology  essay sample that was written by professional writer. If you like one, you have an opportunity to buy a similar paper. Any of the academic papers will be written from scratch, according to all customers’ specifications, expectations and highest standards.”