File system conversion

Details File system conversion File system conversion

2000-07-07

2002-04-23

Alam, Hosain T. (Department: 2172)

Data processing: database and file management or data structures

Database design

Data structure types

Reexamination Certificate

active

06377958

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to in-place conversion of a computer disk partition's file system without archiving or destroying user data, and more particularly to conversion from an “advanced file system” such as NTFS to a FAT file system.
TECHNICAL BACKGROUND OF THE INVENTION
Storage Media
Computers utilize a wide variety of disks as storage media for user data. Disk technologies currently provide optical disks, magnetic disks, hard disks, floppy disks, and removable disks, and new disk technologies are being actively researched and developed. Indeed, some disks used by computers in the future may be cubical or some other shape rather than flat and circular.
FIG. 1
illustrates a disk
100
attached to a disk drive
102
. The disk
100
illustrates physical characteristics of both floppies and hard disks; flash memory, cubical disks or other disks may appear in different configurations than the one shown here. The disk
100
contains a number of concentric data cylinders such as the cylinder
104
. The cylinder
104
contains several data sectors, including sectors
106
and
108
. The sectors
106
and
108
are located on an upper side
110
of the disk
100
; additional sectors may be located on a lower side
112
of the disk
100
. The sides
110
,
112
of the disk
100
define a platter
114
. A hard disk may contain several platters. The upper side
110
of the disk
100
is accessed by a head
116
mounted on an arm
118
secured to the drive
102
. Optical or cubical disks may be accessed by other means, such as photoemitters or photoreceptors, and flash memory or other memory disks are accessed by electronic circuits familiar to those of skill in the art.
A given sector on the disk
100
may be identified by specifying a head, a cylinder, and a sector within the cylinder. A triplet specifying the head number, cylinder number, and sector number in this manner is known as a “physical sector address.” Alternatively, a given sector may be identified by a logical sector address, which is a single number rather than a triplet of numbers.
Partitions and File Systems
Many disks mold the available space into one or more partitions by using a partition table located on the disk. A wide variety of partitions are used, and more partition types will no doubt be defined over time. Many partitions reside on a single disk, but some use volume sets, stripe sets, mirror sets, or other approaches to store a single partition's data on more than one disk. A partial-list of current partitions and their associated file systems is given below; the trademarks listed are the property of their respective owners. This list includes a variety of 12-bit, 16-bit, and 32-bit FAT file systems and numerous other file systems. The list illustrates the benefit of being able to at least identify a variety of partitions to determine what conversion operations, if any, are both pertinent and supported; it does not follow that each and every partition listed should or must be supported in a commercial product or in an embodiment of the invention described and claimed hereafter:
12-bit FAT
16-bit FAT>=32 MB, Ext INT 13
16-bit FAT, partition<32 MB
16-bit FAT, partition>=32 MB
32-bit FAT
32-bit FAT, Ext INT 13
Advanced UNIX
AIX (Linux)
AIX Bootable (Linux)
AIX bootable partition
AIX data partition
Amoeba bad block table
Amoeba file system
AST Windows swap file
BSDI file system or secondary swap
BSDI swap partition or secondary file system
Coherent file system
Coherent swap partition
Commodore DOS
Compaq diagnostics
Concurrent CP/M, Concurrent DOS
CP/M
CP/M 86
CTOS (Convergent Technologies OS)
Cyrnix
Dell partition spannning multiple drives (array)
Disabled NT FAT volume set (Q114841)
Disabled NT IFS volume set (Q114841) (HPFS)
Disk.Secure Multi-Boot
DOS 3.3+second partition
DOS access (Linux)
DR-DOS 6.0 LOGIN.EXE-secured 12-bit FAT partition
DR-DOS 6.0 LOGIN.EXE-secured 16-bit FAT partition
DR-DOS 6.0 LOGIN.EXE-secured Huge partition
Extended partition or Extended volume
Extended partition, Ext INT 13
EZ-Drive 3.05
FreeBSD/386
GNU HURD
GoldenBow VFeature
Hidden 12-bit FAT
Hidden 16-bit FAT>=32 MB, Ext INT 13
Hidden 16-bit FAT, partition<32 MB
Hidden 16-bit FAT, partition>=32 MB
Hidden 32-bit FAT
Hidden 32-bit FAT, Ext INT 13
Hidden IFS
Installable file system: HPFS, NTFS
LANstep
Linux native file system (ext2fs/xiafs)
Linux Swap partition
Linux/Minix v1.4b+
Mach, MtXinu BSD 4.3 on Mach
Microport System V/386
Minix v1.1-1.4a
Mitac Advanced Disk Manager
Mylex DCE376 EISA SCSI controller, past 1024th cyl
NEC MS-DOS 3.x
NextStep Partition
Novell Netware
Novell Netware (3.11 and 4.1)
Novell Netware 286
Novell Netware 386
NT FAT volume set (Q114841)
NT IFS volume set (Q114841) (HPFS)
Old MINIX (Linux)
Ontrack Disk Manager 6.0 (DDO)
Ontrack Disk Manager, read/write
Ontrack Disk Manager, read-only
Ontrack Disk Manager, write-only
OPUS
OS/2
OS/2 Boot Manager
OS/2 hiding type 04h partition
PC/IX
Personal RISC Boot
Priam EDISK
Prime
QNX
Save to Disk Partition
Secure File System
SpeedStor
SpeedStor 12-bit FAT extended partition
SpeedStor 16-bit FAT extended partition
SpeedStor Dimensions
SpeedStor Storage Dimensions
SplitDrive
Syrinx
UNIX SysV/386, 386/ix
VENIX 80286
XENIX /usr file system
Xenix bad-block table
XENIX root file system
A file system of particular interest here is the NT File System (“NTFS”). Discussions of NTFS are provided in “Inside the Windows NT File System”, by Helen Custer, ISBN 1-55615-660-X, as well as in marketing and technical materials available in hard copy and on the Internet from Microsoft Corporation and other sources. Those of skill in the art will note that these discussions sometimes involve unimplemented specifications or mere speculations.
NTFS contains advanced file system features which make it more complex or difficult to manipulate NTFS partitions than it is to manipulate partitions organized by many existing FAT file systems. More precisely, NTFS combines features such as the use of a database paradigm to support indexing of file attributes; multiple data streams per file; blurring of the distinction between system and user areas; recoverability by use of a log; recoverability by use of transactions; support for large disks; security descriptors constraining access to file objects; Unicode names; support for POSIX features such as links; bad cluster remapping; caching support; virtual memory support; system structure compression; balanced tree directory structures; support for volume spanning, volume sets, stripe sets, mirror sets, and other features which divide a file system's contents between disks or partitions; and/or a relocatable system area. “Attributes” are also known as “data streams”; some advanced file systems allow a single file to hold multiple data streams.
One partition table composition, denoted herein as the “IBM-compatible” partition table, is found on the disks used in many IBM® personal computers and IBM-compatible computers (IBM is a registered trademark of International Business Machines Corporation). In recent years, IBM-compatible computers are sometimes referred to PC-compatible, as computers having an Intel architecture, or even as “Wintel” computers. The term “IBM-compatible” refers nominally to IBM, which was the original source of such computers. However, the items of interest for understanding the present invention are not so much the computer vendor, the processor architecture, or the operating system involved, as they are the partition table and the file systems involved. References to IBM-compatible partition tables herein should be understood accordingly. IBM-compatible partition tables may be used on a wide variety of disks, with a variety of partition and file system types, in a variety of ways. In particular, the partition table format may be changed without necessarily changing file system formats, and vice versa.
As shown in
FIG. 2
, one version of an IBM-compatible partition table
200
includes an Initial Program Loader (“IPL”) identifier
202

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