slb是什么意思?

负载平衡（Load balancing）是一种电子计算机技术，用来在多个计算机（计算机集群）、网络连接、CPU、磁盘驱动器或其他资源中分配负载，以达到优化资源使用、最大化吞吐率、最小化响应时间、同时避免过载的目的。 

使用带有负载平衡的多个服务器组件，取代单一的组件，可以通过冗余提高可靠性。负载平衡服务通常是由专用软件和硬件来完成。

主要作用是将大量作业合理地分摊到多个操作单元上进行执行，用于解决互联网架构中的高并发和高可用的问题。

负载均衡最重要的一个应用是利用多台服务器提供单一服务，这种方案有时也被称为服务器农场。

通常，负载平衡主要应用于Web网站，大型的Internet Relay Chat网络，高流量的文件下载网站，NNTP（Network News Transfer Protocol）服务和DNS服务。现在负载平衡器也开始支持数据库服务，称之为数据库负载平衡器。

对于互联网服务，负载平衡器通常是一个软件程序，这个程序侦听一个外部端口，互联网用户可以通过这个端口来访问服务，而作为负载平衡器的软件会将用户的请求转发给后台内网服务器；

内网服务器将请求的响应返回给负载平衡器，负载平衡器再将响应发送到用户，这样就向互联网用户隐藏了内网结构，阻止了用户直接访问后台（内网）服务器，使得服务器更加安全，可以阻止对核心网络栈和运行在其它端口服务的攻击。

当所有后台服务器出现故障时，有些负载平衡器会提供一些特殊的功能来处理这种情况。例如转发请求到一个备用的负载平衡器、显示一条关于服务中断的消息等。负载平衡器使得IT团队可以显著提高容错能力。它可以自动提供大量的容量以处理任何应用程序流量的增加或减少。

应用

负载均衡对通讯链路的冗余是非常有用的。例如，一家公司可能有多条互联网接入线路以保证某一条故障时仍可以正常接入互联网。

故障转移的架构意味着一条连接正常使用，另外一条连接作为备用，当第一条出现故障时才会被启用。

使用负载均衡器，两条（多条）连接可以都投入使用。有一个设备或者程序实时监控着所有连接的连通性，并且对正在发送的包进行选路。同时使用多条连接可以增加带宽。

许多电信公司在其内部网络或连接到外部网络（其它电信网络）都有多条线路可以使用。为避免某条链路出现网络堵塞，最小化连接其它网络的费用或者提高网络的可靠性，它们使用负载均衡将流量从一条链路转移到另一条链路。

For years, Apple's business has centered around the iPhone, but sales of that once-revolutionary but now commonplace device have slowed. And the entire world of computers has been flipped on its head. Apple has been diversifying beyond hardware, selling iCloud storage to its customers, a $10 a month music streaming service and movies and television shows through iTunes.

But Monday's anticipated announcement takes that diversification to a whole new level. Apple said it was launching a raft of new services, from news to video games and a credit card. Its biggest initiative is entertainment streaming service Apple TV+.

Apple is expected to invest many billions a year, according to analysts, on making video content to compete in a crowded market that includes Amazon, Netflix, Hulu and Disney.

The real magic in consumer technology is happening less and less inside the devices people carry around and more and more in server farms scattered around the world, where massive amounts of data get processed and then transmitted to gadgets like the Amazon Echo or Google Home.

In essence, the gadgets people are excited about buying are becoming vessels for sending and receiving data. And in that area, Apple has fallen behind companies like Google, Amazon and Microsoft, which now pull in significant revenue from selling cloud services, which is a fancy term for data center usage and storage.

The invite Apple sent to invitees said simply, "It's show time." The question now is whether Apple can break a leg.

For years, Apple's business has centered around the iPhone, but sales of that once-revolutionary but now commonplace device have slowed. And the entire world of computers has been flipped on its head. Apple has been diversifyingbeyond hardware, selling iCloudstorage to its customers, a $10 a month music streaming service and movies and television shows through iTunes.

But Monday's anticipatedannouncement takes that diversification to a whole new level. Apple said it was launching a raft ofnew services, from news to video games and a credit card. Its biggest initiative is entertainment streaming service Apple TV+.

Apple is expected to invest many billions a year, according to analysts, on making video content to compete in a crowded market that includes Amazon, Netflix, Hulu and Disney.

The real magic in consumer technology is happening less and less inside the devices people carry around and more and more in server farms scattered around the world, where massive amounts of data get processed and then transmitted to gadgets like the Amazon Echo or Google Home.

In essence, the gadgets people are excited about buying are becoming vessels for sending and receiving data. And in that area, Apple has fallen behind companies like Google, Amazon and Microsoft, which now pull in significant revenue from selling cloud services, which is a fancy term for data center usage and storage.

The invite Apple sent to invitees said simply, "It's show time." The question now is whether Apple can break a leg.

business

n. 生意，业务

center around sth.

以...为中心，围绕着...

近义词：center on sth.

magic

n. 魅力

搭配短语：the magic of the city

consumer technology

消费型科技

服务器农场 (Server farm or Server cluster)

The real magic in consumer technology is happening less and less inside the devices people carry around and more and more in server farms scattered around the world, where massive amounts of data get processed and then transmitted to gadgets like the Amazon Echo or Google Home.

消费型科技的真正魅力正越来越少地显现于人们随身携带的设备上，而是愈发显现于分散在世界各地的服务器农场中。在那，大量的数据经过处理后被传送到 Amazon Echo 或 Google Home 这样的电子产品里。

Amazon Echo

Google Home

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