Operating System Concepts and Techniques Lecture 18 Information management-2* FFS, UFS2, NTFS M. Naghibzadeh Reference M. Naghibzadeh, Operating System Concepts and Techniques, First ed., iUniverse Inc., 2011. To order: www.iUniverse.com , www.barnesandnoble.com, or www.amazon.com * Information management is not usually covered in the first course of operating systems
20
Embed
Operating System Concepts and Techniques Lecture 18 Information management-2* FFS, UFS2, NTFS M. Naghibzadeh Reference M. Naghibzadeh, Operating System.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Operating System Concepts and
Techniques Lecture 18
Information management-2*FFS, UFS2, NTFS
M. Naghibzadeh
ReferenceM. Naghibzadeh, Operating System Concepts and Techniques, First ed., iUniverse Inc., 2011.
To order: www.iUniverse.com, www.barnesandnoble.com, or www.amazon.com
* Information management is not usually covered in the first course of operating systems
0x54 426B Bootstrap Code. 0x1FE 2B End of Sector Marker
* 0x0B, Bytes per sector.
0x0D Sectors per Cluster
0x15 Media descriptor. F8: HD; F0: HD Floppy
0x28 Total sectors.
0x30 Logical cluster number for the MFT
0x38 Logical cluster number copy of the MFT
0x40 Clusters per MFT Record.
0x48 Volume serial
NTFS Master File TableInformation on how to find files and directories
attributes and dataA record based file; each record is 1K
There is at least one record for each file (or directory) called base record
A file’s entire metadata may not fit in one record; in such case, extended records are allocated
A file of variable sizeNot all attribute names are applicable to all filesFirst 16 records are reserved for metadata files,
their name begins with $First four entries are replicated for MFT repair
11
Master File Table
12
$Mft Master file table $MftMirr Mirror copy of Mft $LogFile Log file for recovery $Volume Volume file $AttrDef Attribute definition $ Root directory $Bitmap Bitmap of clusters used $Boot Bootstrap loader $BadClus List of bad clusters $Secure Security descriptors of files $Upcase Case conversion table $Extend Extension: quotas, etc Reserved for future use Reserved for future use Reserved for future use Reserved for future use A User file A User file . . .
0123456789101112131415...
System files
User filesand system and user
files extensions
1K
An MFT recordDifferent sections of a MFT record
13
Some metadata Other MFT records for this file File data clusters Unused
ExampleExample: Suppose a file’s data is stored in
Suppose the following figure is the structure of the files and directories of the specific volume
in which file K’s data is to be located
The absolute path of the file is /C/R/KD
16
B C
RSWX
A D
P
Q L K
Directory
File
Accessing a file and its data...
17
Root directory is stored in record number 5 of MFTSuppose root’s data are stored in say cluster no. 950
Cluster number 950 is accessed, the information is the names and base MFT records of the root directory’s files
and directoriesA sequential or B+ search locates C and its base MFT
record is 125This record is accessed just as C was searched for with record 5 replaced by 125 and C replaced by R, suppose
record 85 is the base MFT record for RNow, K must be found; suppose this is done and the
base MFT record 94 is extracted for file KFrom this base record and its extensions, all metadata
and data of file K can be located
18
NTFS SummaryBerkeley Fast File System was briefly discussedUNIX File System 2 was also briefly introduced
The design details of New Technology File System was studied
Each file on an NTFS volume is represented by a record in a special file called the master file
table (MFT)The first 16 records of MFT are for special filesEach file and directory has a base MFT record and zero or more extended record to store its
metadataDirectories are also viewed as files by NTFS
An example was presented to show how a file’s metadata and data are stored and how we can
locate a file or directory
19
Find outThe advantages of UFS2 over USF
The detailed information stored in base MFT record
What is the purposes of record numbers 12, 13, 14, and 15 of the MFT file
The maximum size of a file whose metadata and data can completely fit in its base MFT record
The purposes of record number four of MFT fileHow we can use two disks as one volume
Which records of the MFT file are duplicatedThe purposes of duplicating some records of the