Editing Shared-nothing architecture (section)

{{Short description|Type of  distributed computing architecture}}
A '''shared-nothing architecture''' ('''SN''') is a [[distributed computing]] [[Software architecture|architecture]] in which each update request is satisfied by a single node (processor/memory/storage unit) in a [[computer cluster]]. The intent is to eliminate contention among nodes. Nodes do not share (independently access) the same memory or storage. 

One alternative architecture is shared everything, in which requests are satisfied by arbitrary combinations of nodes. This may introduce contention, as multiple nodes may seek to update the same data at the same time. It also contrasts with [[Shared-disk architecture|shared-disk]] and [[Shared-memory architecture|shared-memory]] architectures. 

SN eliminates [[single point of failure|single points of failure]], allowing the overall system to continue operating despite failures in individual nodes and allowing individual nodes to upgrade hardware or software without a system-wide shutdown.<ref>{{cite web
 |url = https://blog.netapp.com/blogs/the-advantages-of-a-shared-nothing-architecture-for-truly-non-disruptive-upgrades/
 |title = The Advantages of a Shared Nothing Architecture for Truly Non-Disruptive Upgrades
 |last = Wright
 |first = Dave
 |publisher = netapp.com
 |date = 2014-09-17
 |access-date = 2019-10-31}}
 </ref>

A SN system can scale simply by adding nodes, since no central resource bottlenecks the system.<ref>{{cite web
 | last = Blankenhorn
 | first = Dana
 | title = Shared nothing coming to open source
 | publisher = ZDNet
 | date = February 27, 2006
 | url = http://www.zdnet.com/blog/open-source/shared-nothing-coming-to-open-source/580
 | archive-url = https://web.archive.org/web/20121004020313/http://www.zdnet.com/blog/open-source/shared-nothing-coming-to-open-source/580
 | url-status = dead
 | archive-date = October 4, 2012
 | access-date = June 21, 2012}}</ref> In databases, a term for the part of a database on a single node is a ''[[Shard (database architecture)|shard]]''. A SN system typically partitions its data among many nodes. A refinement is to replicate commonly used but infrequently modified data across many nodes, allowing more requests to be resolved on a single node.