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Data Deduplication
In computing, data deduplication is a technique for eliminating duplicate copies of repeating data. Successful implementation of the technique can improve storage utilization, which may in turn lower capital expenditure by reducing the overall amount of storage media required to meet storage capacity needs. It can also be applied to network data transfers to reduce the number of bytes that must be sent. The deduplication process requires comparison of data 'chunks' (also known as 'byte patterns') which are unique, contiguous blocks of data. These chunks are identified and stored during a process of analysis, and compared to other chunks within existing data. Whenever a match occurs, the redundant chunk is replaced with a small reference that points to the stored chunk. Given that the same byte pattern may occur dozens, hundreds, or even thousands of times (the match frequency is dependent on the chunk size), the amount of data that must be stored or transferred can be greatly reduce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ReFS
Resilient File System (ReFS), codenamed "Protogon", is a Microsoft proprietary file system introduced with Windows Server 2012 with the intent of becoming the "next generation" file system after NTFS. ReFS was designed to overcome problems that had become significant over the years since NTFS was conceived, which are related to how data storage requirements have changed. These requirements arose from two major changes in storage systems and usage – the size of storage in use ( large or massive arrays of multi-terabyte drives now common), and the need for continual reliability. As a result, the file system needs to be self-repairing (to prevent disk checking from being impractically slow or disruptive), along with abstraction or virtualization between physical disks and logical volumes. The key design advantages of ReFS include automatic integrity checking and data scrubbing, elimination of the need for running chkdsk, protection against data degradation, bui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and software. Computing has scientific, engineering, mathematical, technological, and social aspects. Major computing disciplines include computer engineering, computer science, cybersecurity, data science, information systems, information technology, and software engineering. The term ''computing'' is also synonymous with counting and calculation, calculating. In earlier times, it was used in reference to the action performed by Mechanical computer, mechanical computing machines, and before that, to Computer (occupation), human computers. History The history of computing is longer than the history of computing hardware and includes the history of methods intended for pen and paper (or for chalk and slate) with or without the aid of tables. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copy-on-write
Copy-on-write (COW), also called implicit sharing or shadowing, is a resource-management technique used in programming to manage shared data efficiently. Instead of copying data right away when multiple programs use it, the same data is shared between programs until one tries to modify it. If no changes are made, no private copy is created, saving resources. A copy is only made when needed, ensuring each program has its own version when modifications occur. This technique is commonly applied to memory, files, and data structures. In virtual memory management Copy-on-write finds its main use in operating systems, sharing the physical memory of computers running multiple processes, in the implementation of the fork() system call. Typically, the new process does not modify any memory and immediately executes a new process, replacing the address space entirely. It would waste processor time and memory to copy all of the old process's memory during the fork only to immediately dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptographic Hash Function
A cryptographic hash function (CHF) is a hash algorithm (a map (mathematics), map of an arbitrary binary string to a binary string with a fixed size of n bits) that has special properties desirable for a cryptography, cryptographic application: * the probability of a particular n-bit output result (hash value) for a random input string ("message") is 2^ (as for any good hash), so the hash value can be used as a representative of the message; * finding an input string that matches a given hash value (a ''pre-image'') is infeasible, ''assuming all input strings are equally likely.'' The ''resistance'' to such search is quantified as security strength: a cryptographic hash with n bits of hash value is expected to have a ''preimage resistance'' strength of n bits, unless the space of possible input values is significantly smaller than 2^ (a practical example can be found in ); * a ''second preimage'' resistance strength, with the same expectations, refers to a similar problem of f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Backup
In information technology, a backup, or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event. The verb form, referring to the process of doing so, is "wikt:back up, back up", whereas the noun and adjective form is "wikt:backup, backup". Backups can be used to data recovery, recover data after its loss from File deletion, data deletion or Data corruption, corruption, or to recover data from an earlier time. Backups provide a simple form of IT disaster recovery; however not all backup systems are able to reconstitute a computer system or other complex configuration such as a computer cluster, active directory server, or database server. A backup system contains at least one copy of all data considered worth saving. The computer data storage, data storage requirements can be large. An information repository model may be used to provide structure to this storage. There are different types of data stor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data
Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted formally. A datum is an individual value in a collection of data. Data are usually organized into structures such as tables that provide additional context and meaning, and may themselves be used as data in larger structures. Data may be used as variables in a computational process. Data may represent abstract ideas or concrete measurements. Data are commonly used in scientific research, economics, and virtually every other form of human organizational activity. Examples of data sets include price indices (such as the consumer price index), unemployment rates, literacy rates, and census data. In this context, data represent the raw facts and figures from which useful information can be extracted. Data are collected using technique ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Email Server
Within the Internet email system, a message transfer agent (MTA), mail transfer agent, or mail relay is software that transfers electronic mail messages from one computer to another using the Simple Mail Transfer Protocol. In some contexts, the alternative names mail server, mail exchanger, or MX host are used to describe an MTA. Messages exchanged across networks are passed between mail servers, including any attached data files (such as images, multimedia, or documents). These servers often keep mailboxes for email. Access to this email by end users is typically either by webmail or an email client. Operation A message transfer agent receives mail from either another MTA, a mail submission agent (MSA), or a mail user agent (MUA). The transmission details are specified by the Simple Mail Transfer Protocol (SMTP). When a recipient mailbox of a message is not hosted locally, the message is relayed, that is, forwarded to another MTA. Every time an MTA receives an email message, it a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single-instance Storage
Single-instance storage (SIS) is a system's ability to take multiple copies of content and replace them by a single shared copy. It is a means to eliminate data duplication and to increase efficiency. SIS is frequently implemented in file systems, e-mail server software, data backup, and other storage-related computer software. Single-instance storage is a simple variant of data deduplication. While data deduplication may work at a segment or sub-block level, single-instance storage works at the whole-file level and eliminates redundant copies of entire files or e-mail messages. Concept In the case of an e-mail server, single-instance storage would mean that a single copy of a message is held within its database while individual mailboxes access the content through a reference pointer. However, there is a common misconception that the primary benefit of single-instance storage in mail servers is a reduction in disk space requirements. The truth is that its primary benefit is to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Write Anywhere File Layout
The Write Anywhere File Layout (WAFL) is a proprietary file system that supports large, high-performance Redundant array of independent disks, RAID arrays, quick restarts without lengthy consistency checks in the event of a Crash (computing), crash or power failure, and growing the filesystems size quickly. It was designed by NetApp for use in its storage appliances like NetApp FAS, NetApp FAS, AFF, ONTAP#Cloud Volumes ONTAP, Cloud Volumes ONTAP and ONTAP#ONTAP Select, ONTAP Select. Its author claims that WAFL is not a file system, although it includes one. It tracks changes similarly to journaling file systems as logs (known as NVLOGs) in dedicated memory storage device non-volatile random access memory, referred to as NVRAM or NVMEM. WAFL provides mechanisms that enable a variety of file systems and technologies that want to access Block (data storage), disk blocks. Design WAFL stores metadata, as well as data, in files; metadata, such as inodes and block maps indicating wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pigeonhole Principle
In mathematics, the pigeonhole principle states that if items are put into containers, with , then at least one container must contain more than one item. For example, of three gloves, at least two must be right-handed or at least two must be left-handed, because there are three objects but only two categories of handedness to put them into. This seemingly obvious statement, a type of combinatorics, counting argument, can be used to demonstrate possibly unexpected results. For example, given that the Demographics of London, population of London is more than one unit greater than the maximum number of hairs that can be on a human's head, the principle requires that there must be at least two people in London who have the same number of hairs on their heads. Although the pigeonhole principle appears as early as 1624 in a book attributed to Jean Leurechon, it is commonly called Dirichlet's box principle or Dirichlet's drawer principle after an 1834 treatment of the principle by Pet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
