Grid Storage

Definition: Grid storage, analogous to grid computing, is a new model for deploying and managing storage distributed across multiple systems and networks, making efficient use of available storage capacity without requiring a large, centralized switching system.

A grid is, in fact, a meshed network in which no single centralized switch or hub controls routing. Grids offer almost unlimited scalability in size and performance because they aren't constrained by the need for ever-larger central switches. Grid networks thus reduce component costs and produce a reliable and resilient structure.

Applying the grid concept to a computer network lets us harness available but unused resources by dynamically allocating and deallocating capacity, bandwidth and processing among numerous distributed computers. A computing grid can span locations, organizations, machine architectures and software boundaries, offering power, collaboration and information access to connected users. Universities and research facilities are using grids to build what amounts to supercomputer capability from PCs, Macintoshes and Linux boxes.

After grid computing came into being, it was only a matter of time before a similar model would emerge for making use of distributed data storage. Most storage networks are built in star configurations, where all servers and storage devices are connected to a single central switch. In contrast, grid topology is built with a network of interconnected smaller switches that can scale as bandwidth increases and continue to deliver improved reliability and higher performance and connectivity.

What Is Grid Storage?

Based on current and proposed products, it appears that a grid storage system should include the following:

Modular storage arrays: These systems are connected across a storage network using serial ATA disks. The systems can be block-oriented storage arrays or network-attached storage gateways and servers.

Common virtualization layer: Storage must be organized as a single logical pool of resources available to users.

Data redundancy and availability: Multiple copies of data should exist across nodes in the grid, creating redundant data access and availability in case of a component failure.

Common management: A single level of management across all nodes should cover the areas of data security, mobility and migration, capacity on demand, and provisioning.

Simplified platform/management architecture: Because common management is so important, the tasks involved in administration should be organized in modular fashion, allowing the autodiscovery of new nodes in the grid and automating volume and file management.

Three Basic Benefits

Applying grid topology to a storage network provides several benefits, including the following:

Reliability. A well-designed grid network is extremely resilient. Rather than providing just two paths between any two nodes, the grid offers multiple paths between each storage node. This makes it easy to service and replace components in case of failure, with minimal impact on system availability or downtime.

Performance. The same factors that lead to reliability also can improve performance. Not requiring a centralized switch with many ports eliminates a potential performance bottleneck, and applying load-balancing techniques to the multiple paths available offers consistent performance for the entire network.

Scalability. It's easy to expand a grid network using inexpensive switches with low port counts to accommodate additional servers for increased performance, bandwidth and capacity. In essence, grid storage is a way to scale out rather than up, using relatively inexpensive storage building blocks.

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網(wǎng)格存儲

定義：網(wǎng)格存儲與網(wǎng)格計算類似，是部署和管理分布在多個系統(tǒng)和網(wǎng)絡(luò)上的存儲的新模式，在無需集中式大型交換系統(tǒng)的情況下，高效地利用可資使用的存儲容量。

網(wǎng)格實際上是一個網(wǎng)狀網(wǎng)絡(luò)，其中沒有控制路由的單個集中式交換機或集線器。網(wǎng)格在規(guī)模和性能上提供了無限的擴展性，因為它們不會受越來越大的集中式中央交換機這個需求的束縛。因此，網(wǎng)格網(wǎng)絡(luò)降低了構(gòu)件的成本，生成一個可靠且有彈性的結(jié)構(gòu)。

將網(wǎng)格概念應(yīng)用于計算機網(wǎng)絡(luò)，讓我們通過動態(tài)分配和重新分配數(shù)量眾多的分布式計算機的容量、帶寬和處理能力，利用可用但未用的資源。計算網(wǎng)格可以跨越地域、機構(gòu)、機器架構(gòu)和軟件界限，給連接著的用戶提供處理能力、協(xié)作和信息存取。大學(xué)和研究機構(gòu)正在利用網(wǎng)格提供 PC機、蘋果機和Linux機組成的、可與巨型機匹敵的計算能力。

有了網(wǎng)格計算之后，出現(xiàn)利用分布數(shù)據(jù)存儲的類似模型只是個時間問題。大多數(shù)存儲網(wǎng)絡(luò)是星型結(jié)構(gòu)，其中所有服務(wù)器和存儲設(shè)備都與單一的中央交換機相連。相反，網(wǎng)格的拓撲結(jié)構(gòu)是互聯(lián)在一起的小服務(wù)器網(wǎng)絡(luò)，可以隨著帶寬的增加而增加服務(wù)器，繼續(xù)提供更好的可靠性和更高的性能及連接性。

何為網(wǎng)格存儲?

基于目前已有的和建議中的產(chǎn)品，網(wǎng)格存儲系統(tǒng)應(yīng)該包括下列組成部分：

模塊化存儲陣列：這些系統(tǒng)連接在一個使用串行 ATA磁盤的存儲網(wǎng)絡(luò)。系統(tǒng)可以是基于塊的存儲陣列，也可以是接在網(wǎng)絡(luò)上的NAS網(wǎng)關(guān)和服務(wù)器。

公共虛擬層：存儲被組織成一個邏輯資源庫，以供用戶使用。

數(shù)據(jù)冗余和可用性：數(shù)據(jù)的多個拷貝應(yīng)該存在于網(wǎng)格的節(jié)點上，在部件出現(xiàn)故障時保證冗余數(shù)據(jù)的存取和可用性。

公共管理：對所有節(jié)點的單一管理層次應(yīng)該覆蓋數(shù)據(jù)安全、機動性和遷移性、按需能力供應(yīng)和預(yù)備功能等諸多方面。

簡化的平臺 /管理架構(gòu): 由于公共的管理非常重要，管理中所涉及的任務(wù)應(yīng)該按模塊方式組織好，允許自動發(fā)現(xiàn)網(wǎng)格中的節(jié)點和自動完成卷及文件的管理。

三大基本優(yōu)勢

將網(wǎng)格拓撲應(yīng)用于存儲網(wǎng)絡(luò)帶來了諸多的好處，其中包括下列優(yōu)勢：

可靠性 : 一個設(shè)計良好的網(wǎng)格極具彈性。網(wǎng)格不只是在任何兩個節(jié)點之間提供兩個通道，而是在每個存儲節(jié)點之間提供多個通道。這就使維修服務(wù)和出故障時更換部件比較容易，對系統(tǒng)的可用性或宕機時間影響最小。

性能：導(dǎo)致高可靠性的因素同樣也能改善性能。不需要有大量端口的集中式交換機，消除了潛在的性能瓶頸，并能將負載平衡技術(shù)應(yīng)用于可使用的多個通道，為整個網(wǎng)絡(luò)提供一致的性能。

可擴展性 : 利用端口數(shù)不多的廉價交換機，就能很容易地擴展網(wǎng)格網(wǎng)絡(luò)，以適應(yīng)為提高性能、帶寬和容量而增加的服務(wù)器。本質(zhì)上，網(wǎng)格存儲是利用較廉價的存儲設(shè)備來向外擴展而不是向上升級的方法。