Rollback Rx
Encyclopedia
RollBack Rx is a third party disk utility for Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

, that uses a sector
Disk sector
In computer disk storage, a sector is a subdivision of a track on a magnetic disk or optical disc. Each sector stores a fixed amount of user data. Traditional formatting of these storage media provides space for 512 bytes or 2048 bytes of user-accessible data per sector...

 mapping algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...

 and incremental sector redirection to capture and manage its snapshots. This product is marketed under other names and price points such as EAZ-FIX.

Due to its sector based mapping, RollBack Rx does not recreate files
Computer file
A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...

 or folders into a temporary drive
Mass storage
In computing, mass storage refers to the storage of large amounts of data in a persisting and machine-readable fashion. Devices and/or systems that have been described as mass storage include tape libraries, RAID systems, hard disk drives, magnetic tape drives, optical disc drives, magneto-optical...

 space — resulting in a larger capacity of incremental snapshots and faster snapshot times. The RollBack Rx snapshots can be taken manually, on a schedule or when a particular file is executed.

How it works

RollBack Rx installs to the hard drive's master boot record
Master boot record
A master boot record is a type of boot sector popularized by the IBM Personal Computer. It consists of a sequence of 512 bytes located at the first sector of a data storage device such as a hard disk...

, which loads prior to the Windows operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

, which allows the hard drive to be reverted to a previous snapshot state even in the event that Windows is unable to boot
Booting
In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...

. The user can also select to revert to a snapshot from within Windows, which requires a reboot or logoff to take effect.

Description

A snapshot
Snapshot (computer storage)
In computer systems, a snapshot is the state of a system at a particular point in time. The term was coined as an analogy to that in photography. It can refer to an actual copy of the state of a system or to a capability provided by certain systems....

 is a bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...

-for-bit map of the hard disk sector
Disk sector
In computer disk storage, a sector is a subdivision of a track on a magnetic disk or optical disc. Each sector stores a fixed amount of user data. Traditional formatting of these storage media provides space for 512 bytes or 2048 bytes of user-accessible data per sector...

. It is a record of how the PC's hard drive is configured at the time a snapshot is taken. The snapshot includes all files including system, data
Data
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...

, programs
Computer program
A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...

, settings, the registry
Windows registry
The Windows Registry is a hierarchical database that stores configuration settings and options on Microsoft Windows operating systems. It contains settings for low-level operating system components as well as the applications running on the platform: the kernel, device drivers, services, SAM, user...

, wallpaper
Computer wallpaper
Wallpaper is an image used as a background of a graphical user interface on a computer screen or mobile communications device. On a computer it is usually for the desktop, while for a mobile phone it is usually the background for the 'home' or 'idle' screen...

, icons
Icon (computing)
A computer icon is a pictogram displayed on a computer screen and used to navigate a computer system or mobile device. The icon itself is a small picture or symbol serving as a quick, intuitive representation of a software tool, function or a data file accessible on the system. It functions as an...

, etc.

Incremental sector redirection

RollBack Rx's core algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...

 is based on incremental sector redirection. Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 operates at a cluster
Cluster (file system)
In computer file systems, a cluster or allocation unit is the unit of disk space allocation for files and directories. To reduce the overhead of managing on-disk data structures, the filesystem does not allocate individual disk sectors, but contiguous groups of sectors, called clusters.On a disk...

 level, which consists of multiple disk sectors. RollBack Rx works at the disk sector
Disk sector
In computer disk storage, a sector is a subdivision of a track on a magnetic disk or optical disc. Each sector stores a fixed amount of user data. Traditional formatting of these storage media provides space for 512 bytes or 2048 bytes of user-accessible data per sector...

 level.

When a snapshot is taken, RollBack Rx freezes sectors to their current data. If Windows attempts to update that particular sector, RollBack Rx grabs the write and redirects it into unprotected sectors. If Windows attempts to delete that sector, Rollback Rx intercepts the delete. Additional snapshots freezes only those sectors that have been written since the last snapshot.

Incompatible products

It can be beneficial to disable RollBack Rx prior to using any Windows defragmentation
Defragmentation
In the maintenance of file systems, defragmentation is a process that reduces the amount of fragmentation. It does this by physically organizing the contents of the mass storage device used to store files into the smallest number of contiguous regions . It also attempts to create larger regions of...

 utility, as file relocations are treated by RollBack Rx as relatively large data changes and can therefore cause large snapshots. The current version 9.1 does not support any third party disk defragmenter. However, defragmentation can be carried out without disabling RollBack Rx, and the data used can be freed by "re-baselining" (which will cause the removal of all snapshots taken so far).

Precautions

RollBack Rx does not support RAID
RAID
RAID is a storage technology that combines multiple disk drive components into a logical unit...

or any server-based operating systems. RollBack Rx will not be accessible at bootup if the Master Boot Record is erased or altered. RollBack Rx, being a Windows application, cannot protect the hard drive from changes occurring under DOS or other operating systems (such as Linux).

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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