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Data Striping
In computer data storage, data striping is the technique of segmenting logically sequential data, such as a file, so that consecutive segments are stored on different physical storage devices. Striping is useful when a processing device requests data more quickly than a single storage device can provide it. By spreading segments across multiple devices which can be accessed concurrently, total data throughput is increased. It is also a useful method for balancing I/O load across an array of disks. Striping is used across disk drives in redundant array of independent disks (RAID) storage, network interface controllers, disk arrays, different computers in clustered file systems and grid-oriented storage, and RAM in some systems. Method One method of striping is done by interleaving sequential segments on storage devices in a round-robin fashion from the beginning of the data sequence. This works well for streaming data, but subsequent random accesses will require knowledge of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Data Storage
Computer data storage is a technology consisting of computer components and Data storage, recording media that are used to retain digital data (computing), data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a computer is what manipulates data by performing computations. In practice, almost all computers use a memory hierarchy, storage hierarchy, which puts fast but expensive and small storage options close to the CPU and slower but less expensive and larger options further away. Generally, the fast volatile technologies (which lose data when off power) are referred to as "memory", while slower persistent technologies are referred to as "storage". Even the first computer designs, Charles Babbage's Analytical Engine and Percy Ludgate's Analytical Machine, clearly distinguished between processing and memory (Babbage stored numbers as rotations of gears, while Ludgate stored numbers as displacements of rods in shuttles). Thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sybase
Sybase, Inc. was an enterprise software and services company. The company produced software to manage and analyze information in relational databases, with facilities located in California and Massachusetts. Sybase was acquired by SAP in 2010; SAP ceased using the Sybase name in 2014. History *1984: Robert Epstein, Mark Hoffman, Jane Doughty, and Tom Haggin founded Sybase (initially trading as ''Systemware'') in Epstein's home in Berkeley, California. Their first commercial location is half of an office suite at 2107 Dwight Way in Berkeley. They set out to create a relational database management system (RDBMS) that will organize information and make it available to computers within a network. *March 1986: Systemware enters into talks with Microsoft to license Data Server, a database product built to run on UNIX computers. Those talks led to a product called Ashton-Tate/Microsoft SQL Server 1.0, shipping in May 1989. *May 1991: Systemware changes its name to Sybase. *January 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Link Aggregation
In computer networking, link aggregation is the combining ( aggregating) of multiple network connections in parallel by any of several methods, in order to increase throughput beyond what a single connection could sustain, to provide redundancy in case one of the links should fail, or both. A link aggregation group (LAG) is the combined collection of physical ports. Other umbrella terms used to describe the concept include trunking, bundling, bonding, channeling or teaming. Implementation may follow vendor-independent standards such as Link Aggregation Control Protocol (LACP) for Ethernet, defined in IEEE 802.1AX or the previous IEEE 802.3ad, but also proprietary protocols. Motivation Link aggregation increases the bandwidth and resilience of Ethernet connections. Bandwidth requirements do not scale linearly. Ethernet bandwidths historically have increased tenfold each generation: 10 megabit/s, 100 Mbit/s, 1000 Mbit/s, 10,000 Mbit/s. If one started to bump in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Partition Alignment
Partition alignment is the proper alignment of partitions to the boundaries available in a data storage device. Examples include the following: * 4 KB sector alignment with hard disk drives supporting Advanced Format (AF) * Track partition alignment, partitions starting on track boundaries on hard disk drives * Cylinder partition alignment, partitions starting on logical or physical cylinder boundaries on hard disk drives * SSD page partition alignment, partitions starting on NVM page boundaries (with pages typically 4 to 16 KB in size) on SSDs and other flash-based memory devices * SSD block partition alignment, partitions starting on NVM block boundaries (typically blocks of 128 to 512 pages) on SSDs and other flash-based memory devices * 1 MB partition alignment, partitions starting on 1 MB boundaries * RAID stripe alignment, partition alignment based on stripe boundaries See also * Advanced Format * Data striping In computer data storage, data striping ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NVM Express
NVM Express (NVMe) or Non-Volatile Memory Host Controller Interface Specification (NVMHCIS) is an open, logical-device interface specification for accessing a computer's non-volatile storage media usually attached via PCI Express (PCIe) bus. The initialism ''NVM'' stands for ''non-volatile memory'', which is often NAND flash memory that comes in several physical form factors, including solid-state drives (SSDs), PCIe add-in cards, and M.2 cards, the successor to mSATA cards. NVM Express, as a logical-device interface, has been designed to capitalize on the low latency and internal parallelism of solid-state storage devices. Architecturally, the logic for NVMe is physically stored within and executed by the NVMe controller chip that is physically co-located with the storage media, usually an SSD. Version changes for NVMe, e.g., 1.3 to 1.4, are incorporated within the storage media, and do not affect PCIe-compatible components such as motherboards and CPUs. By its design, NVM Exp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disk Mirroring
In data storage, disk mirroring is the replication of logical disk volumes onto separate physical hard disks in real time to ensure continuous availability. It is most commonly used in RAID 1. A mirrored volume is a complete logical representation of separate volume copies. In a disaster recovery context, mirroring data over long distance is referred to as storage replication. Depending on the technologies used, replication can be performed synchronously, asynchronously, semi-synchronously, or point-in-time. Replication is enabled via microcode on the disk array controller or via server software. It is typically a proprietary solution, not compatible between various data storage device vendors. Mirroring is typically only synchronous. Synchronous writing typically achieves a recovery point objective (RPO) of zero lost data. Asynchronous replication can achieve an RPO of just a few seconds while the remaining methodologies provide an RPO of a few minutes to perhaps several hou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logical Volume Management
In computer storage, logical volume management or LVM provides a method of allocating space on mass-storage devices that is more flexible than conventional partitioning schemes to store volumes. In particular, a volume manager can concatenate, stripe together or otherwise combine partitions (or block devices in general) into larger virtual partitions that administrators can re-size or move, potentially without interrupting system use. Volume management represents just one of many forms of storage virtualization; its implementation takes place in a layer in the device-driver stack of an operating system (OS) (as opposed to within storage devices or in a network). Design Most volume-manager implementations share the same basic design. They start with physical volumes (PVs), which can be either hard disks, hard disk partitions, or Logical Unit Numbers (LUNs) of an external storage device. Volume management treats each PV as being composed of a sequence of chunks called phy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redundancy (information Theory)
In information theory, redundancy measures the fractional difference between the entropy of an ensemble , and its maximum possible value \log(, \mathcal_X, ). Informally, it is the amount of wasted "space" used to transmit certain data. Data compression is a way to reduce or eliminate unwanted redundancy, while forward error correction is a way of adding desired redundancy for purposes of error detection and correction when communicating over a noisy channel of limited capacity. Quantitative definition In describing the redundancy of raw data, the rate of a source of information is the average entropy per symbol. For memoryless sources, this is merely the entropy of each symbol, while, in the most general case of a stochastic process, it is :r = \lim_ \frac H(M_1, M_2, \dots M_n), in the limit, as ''n'' goes to infinity, of the joint entropy of the first ''n'' symbols divided by ''n''. It is common in information theory to speak of the "rate" or "entropy" of a language. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard RAID Levels
In computer storage, the standard RAID levels comprise a basic set of RAID ("redundant array of independent disks" or "redundant array of inexpensive disks") configurations that employ the techniques of striping, mirroring, or parity to create large reliable data stores from multiple general-purpose computer hard disk drives (HDDs). The most common types are RAID 0 (striping), RAID 1 (mirroring) and its variants, RAID 5 (distributed parity), and RAID 6 (dual parity). Multiple RAID levels can also be combined or ''nested'', for instance RAID 10 (striping of mirrors) or RAID 01 (mirroring stripe sets). RAID levels and their associated data formats are standardized by the Storage Networking Industry Association (SNIA) in the Common RAID Disk Drive Format (DDF) standard. The numerical values only serve as identifiers and do not signify performance, reliability, generation, or any other metric. While most RAID levels can provide good protection against and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Automatic Storage Management
Automatic Storage Management (ASM) is a feature provided by Oracle Corporation within the Oracle Database from release Oracle 10g (revision 1) onwards. ASM aims to simplify the management of database datafiles, control files and log files. To do so, it provides tools to manage file systems and volumes directly inside the database, allowing database administrators (DBAs) to control volumes and disks with familiar SQL statements in standard Oracle environments. Thus DBAs do not need extra skills in specific file systems or volume managers (which usually operate at the level of the operating system). Features * IO channels can take advantage of data striping and software mirroring * DBAs can automate online redistribution of data, along with the addition and removal of disks/storage * the system maintains redundant copies and provides 3rd-party RAID functionality * Oracle supports third-party multipathing IO technologies (such as failover or load balancing to SAN access) * the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oracle Corporation
Oracle Corporation is an American multinational computer technology corporation headquartered in Austin, Texas. In 2020, Oracle was the third-largest software company in the world by revenue and market capitalization. The company sells database software and technology (particularly its own brands), cloud engineered systems, and enterprise software products, such as enterprise resource planning (ERP) software, human capital management (HCM) software, customer relationship management (CRM) software (also known as customer experience), enterprise performance management (EPM) software, and supply chain management (SCM) software. History Larry Ellison co-founded Oracle Corporation in 1977 with Bob Miner and Ed Oates under the name Software Development Laboratories (SDL). Ellison took inspiration from the 1970 paper written by Edgar F. Codd on relational database management systems ( RDBMS) named "A Relational Model of Data for Large Shared Data Banks." He heard about the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Cluster
A computer cluster is a set of computers that work together so that they can be viewed as a single system. Unlike grid computers, computer clusters have each node set to perform the same task, controlled and scheduled by software. The components of a cluster are usually connected to each other through fast local area networks, with each node (computer used as a server) running its own instance of an operating system. In most circumstances, all of the nodes use the same hardware and the same operating system, although in some setups (e.g. using Open Source Cluster Application Resources (OSCAR)), different operating systems can be used on each computer, or different hardware. Clusters are usually deployed to improve performance and availability over that of a single computer, while typically being much more cost-effective than single computers of comparable speed or availability. Computer clusters emerged as a result of convergence of a number of computing trends including t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
