Error detection/correction and fault detection/recovery – Data processing system error or fault handling – Reliability and availability
Reexamination Certificate
2000-03-22
2003-09-02
Iqbal, Nadeem (Department: 2709)
Error detection/correction and fault detection/recovery
Data processing system error or fault handling
Reliability and availability
C714S054000, C711S162000, C711S161000
Reexamination Certificate
active
06615365
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to storing and recovering computer disk images in a computer partition. More particularly, the invention provides tools and techniques for placing images in the same partition that is being imaged, and for extracting information from images stored in the imaged partition, thereby allowing single large partitions to be used more effectively.
TECHNICAL BACKGROUND OF THE INVENTION
Computers Generally
Computer hard disks and other computer storage devices hold digital data which represents numbers, names, dates, text, pictures, sounds and other information used by businesses, individuals, government agencies, and others. To help organize the data, and for technical reasons, many computers divide the data into drives, partitions, directories, and files. The terms “file” and “directory” are familiar to most computer users, and most people agree on their meaning even though the details of written definitions vary.
However, the terms “partition” and “drive” have different meanings even when the context is limited to computers. According to some definitions, a partition is necessarily limited to one storage device, but a “file system” may include one or more partitions, on one or more disks. Many partitions reside on a single disk, but some approaches, such as volume sets, stripe sets, mirror sets, and others, store a single partition's data on more than one disk.
As used here, a “partition” is a region on one or more storage devices which is (or can be) formatted to contain one or more files or directories. A partition may be empty. A partition may also be in active use even without any directories, file allocation tables, bitmaps, or similar file system structures if it holds a stream or block of raw data. Each formatted partition is tailored to a particular type of file system, such as the Macintosh file system, SunOS file system (a variant of the UNIX file system), Linux file system (EXT2fs, a variant of the UNIX file system), Windows NT File System (“NTFS”), NetWare file system, Linux file system, or one of the MS-DOS/FAT file systems. (MACINTOSH is a trademark of Apple Computer, Inc.; SunOS is a trademark of Sun Microsystems, Inc.; WINDOWS NT and MS-DOS are trademarks of Microsoft Corporation; NETWARE is a trademark of Novell, Inc.; LINUX is a mark of Linus Torvalds).
Computers utilize a wide variety of storage devices as storage media for user data. Storage technologies currently provide removable optical, and magnetic disks, fixed and removable hard disks, floppy disks, solid state storage devices, and new storage technologies are continually being actively researched and developed. Indeed, some storage devices used by computers in the future may be cubical or some other shape with no moving parts rather than flat and circular, and in addition, storage devices which use computer chips as storage media are being developed. Disks, storage devices and related concepts such as cylinders, sectors, platters, tracks, heads, physical sector addresses, and logical sector addresses are generally familiar in the art. For instance, they are discussed in U.S. Pat. Nos. 5,675,769 and 5,706,472 assigned to PowerQuest Corporation, and those discussions are incorporated herein by this reference.
An operating system manages access, not only to the disks, but to other computer resources as well. Resources typically managed by the operating system include one or more disks and disk drives, memory (RAM and/or ROM), microprocessors, and I/O devices such as a keyboard, mouse, screen, printer, tape drive, modem, serial port, parallel port, or network port.
Many disks mold the available space into one or more partitions by using a partition table located on the disk. A wide variety of partition types are used, and more partition types will no doubt be defined over time. A partial list of current partitions and their associated file systems is given in U.S. patent application Ser. No. 08/834,004 and incorporated here by reference. The list includes a variety of 12-bit, 16-bit, and 32-bit FAT file systems and numerous other file systems. Tools and techniques for manipulating FAT and certain other partitions are described in U.S. Pat. Nos. 5,675,769 and 5,706,472 assigned to PowerQuest Corporation, incorporated herein by this reference.
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). Although IBM is not the only present source of personal computers, server computers, and computer operating systems and/or file system software, the term “IBM-compatible” is widely used in the industry to distinguish certain computer systems from other computer systems such as Macintosh computer systems produced by Apple Computer (Macintosh is a market of Apple Computer) and UNIX computer systems. 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.
As shown in U.S. Pat. Nos. 5,675,769 and 5,706,472, one version of an IBM-compatible partition table includes an Initial Program Loader (“IPL”) identifier, four primary partition identifiers, and a boot identifier. As also shown in those patents, each partition identifier includes a boot indicator to indicate whether the partition in question is bootable. At most one of the partitions in the set of partitions defined by the partition table is bootable at any given time.
Each partition identifier also includes a starting address, which is the physical sector address of the first sector in the partition in question, and an ending address, which is the physical sector address of the last sector in the partition. A sector count holds the total number of disk sectors in the partition. A boot sector address holds the logical sector address corresponding to the physical starting address.
Some IBM-compatible computer systems allow “logical partitions” as well as the primary partitions just described. All logical partitions are contained within one primary partition; a primary partition which contains logical partitions is also known as an “extended partition.”
Each partition identifier also includes a system indicator. The system indicator identifies the type of file system contained in the partition, which in turn defines the physical arrangement of data that is stored in the partition on the disk. Values not recognized by a particular operating system are treated as designating an unknown file system. The file system associated with a specific partition of the disk determines the format in which data is stored in the partition, namely, the physical arrangement of user data and of file system structures in the portion of the disk that is delimited by the starting address and the ending address of the partition in question. At any given time, each partition thus contains at most one type of file system.
Data Backup Approaches
Many computers are sold with operating systems, application programs, and other data already loaded on the disk. Manufacturers and vendors of computers often would like to provide users with a backup or image of the information they originally loaded on a hard drive. Two basic approaches are used in conventional systems and methods to backup computer data. One approach is generally file-oriented, while the other approach deals with files but operates primarily on clusters, sectors, runs, or similar logical allocation units which are smaller than files.
A file-oriented backup approach is illustrated in
FIG. 1. A
partition
100
includes system data
102
and user data
104
. The system data
102
includes file system data such as sector or cluster allocation maps or tables and directories. The system data
102
also includes operating system data such as partition tables and boot code. The user data
104
includes data created by users, such as word processor or spreadsheet files, as well as application programs,
Arbon Val A.
Jenevein Roy M.
Kramer Heidi S.
Lawrence Andy V.
Shadel Derrick S.
Bonura Tim M.
Computer Law ++
Iqbal Nadeem
PowerQuest Corporation
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